MICHELIN TRUCK TIRE. SERVICE MANUAL (2017)

AUTOMATED TIRE INFLATION SYSTEM

of the Automated Tire Inflation System (ATIS) will only

come on if the pressure in the tire drops below a certain

(ATIS) OR TIRE PRESSURE MONITORING

percent (usually 10%) of the regulated preset pressure. Even

SYSTEM (TPMS)

when the pressure drops below this point, the light will go

Maintaining proper tire inflation will help maximize tire

off if the system is able to restore and maintain the preset

life and casing durability. This can result in reduced overall

pressure.

tire costs, downtime, tire replacement, irregular wear,

If you have any questions, please contact Michelin

wheel replacement, road debris, and the natural resources

Consumer Care at 1-888-622-2306.

required to manufacture tires and retreads. Correct

inflation will help increase benefits such as fuel efficiency,

safety, driver retention, and uptime, all of which have a

DRIVE CAREFULLY

direct effect on cost per mile.

All tires will wear out faster when subjected to high

While these systems may reduce tire labor, it is still

speeds as well as hard cornering, rapid starts, sudden stops,

necessary to inspect tires to ensure they are serviceable,

and frequent driving on surfaces that are in poor condition.

properly inflated, and the systems are working correctly.

Surfaces with holes and rocks or other objects can damage

All of these systems need to be properly installed and

tires and cause vehicle misalignment. When you drive on

maintained to deliver the benefits they provide.

such surfaces, drive on them carefully and slowly, and

Most of the systems on the market are capable of

before driving at normal or highway speeds, examine your

maintaining a cold inflation pressure within the capacity

tires for any damage, such as cuts or penetrations.

of the truck’s air system. The use of these systems does not

nullify the MICHELIN^®Truck Tire Operator’s Manual and

TREAD DEPTH MEASUREMENTS

Limited Warranty (MWE40021) unless it is determined that

Tires should be measured for wear. This measurement

the system somehow contributed to the failure or reduced

can be taken in several spots across the tread and around

performance of the tire. Proper pressure maintenance is

the circumference. However, to calculate the remaining

important for the optimized performance of the tires, so

amount of rubber (knowing the new tire tread depth) for

it is important to make sure the system can maintain the

a given number of miles run, the measurement should

pressures needed and/or can detect accurately when the

always be taken at the same spot on the tread and should

pressures are outside of the normal operating range(s) for

be taken close to the center of the groove, in order to not

the loads being carried. Some inflation systems will add

get a false reading due to the radius of the groove bottom,

pressure when cold weather temperature drops the psi

as shown below.

below that which the system is calibrated for, resulting in a

pressure higher than the target setting. For example,

a 40 degree temperature drop will reduce pressure readings

by 6 to 8 pounds psi, thus the inflation system will increase

the pressure above the target by a like amount. Tires on

vehicles with these systems should still be gauged weekly

and cold pressure adjusted if necessary.

Michelin does not and cannot test every system that

is being marketed/manufactured for effectiveness,

performance, and durability. It is the responsibility of the

system manufacturer to ensure that the tires are inflated

as rapidly as possible to the optimal operating pressure in

order to prevent internal damage to the tires. In view

of the increasing promotion for the use of pressure

monitoring and/or inflation systems, Michelin strongly

urges the customer to put the responsibility on the system’s

manufacturer to prove and support their claims. Please

refer to the MICHELIN^®Truck Tire Operator’s Manual and

Limited Warranty (MWE40021) for a general discussion of

what is and is not covered by the warranty.

Systems on trailers can sometimes allow slow leaks

caused by nails or other small objects penetrating the

crown area of the tire to go undetected. A slow leak can be

compensated for by the inflation system. The warning light

56 Section Four: Extending Tire Life

WEAR BARS

data for overall width or the width as marked on the

MICHELIN^®truck tires contain “wear bars” in the tread

sidewall of the tire (which may require conversion from

grooves of the tire tread, which show up when only 2/32nds

Metric to English units). It is recommended to contact your

of an inch or less of tread remains. Tread depths should

state’s DOT office to confirm the current Load Per Inch

not be taken on the wear bar indicators. When the tread is

Width Law.

worn level with the wear bar indicators (from either even

For example, if a state allows for 550 pounds per inch

or irregular wear), the tire must be removed from service.

width, a tire marked 11R22.5 could carry up to 6,050

Federal law requires that “any tire on the front wheels of a

pounds (11 x 550) or a total of 12,100 pounds on the steer

bus, truck, or truck tractor shall have a tread groove pattern

axle (2 x 6,050). Another way to look at it is to take the total

depth of at least 4/32 of an inch when measured at any

weight carried and divide by the stated Inch Width Law

point on a major tread groove. The measurements shall not

to determine the appropriate size tire. If a commercial

be made where tie bars, humps, or fillets are located.”

front end loader (sanitation vehicle) wants to carry 20,000

pounds in a state with a 600 pound per inch width limit

(20,000/600 = 33.3), you would need a tire that is at least

16.7 inches wide (33.3/2). In this case a 425/65R22.5 could

legally carry the load (425/25.4 = 16.7 inches Metric to

English conversion).

The two formulas are:

- Load Per Inch Width Law x tire section width x number

of tires = gross axle weight limit

- Gross axle weight / Inch Width Law / number of tires =

minimum tire section width needed

Do not exceed the gross axle weight ratings (GAWR) for any

axle on the vehicle.

Do not exceed the maximum pressure capacity of the

wheel. Consult the wheel manufacturer in these cases.

DRIVE AT PROPER SPEEDS

The maximum continuous speed at which MICHELIN^®

truck tires can be operated is indicated in the MICHELIN^®

data books. See Section Ten, Appendix under Publications,

Videos, and Websites (Page 186-187) for complete listings

of the MICHELIN^®data books. This speed varies for each

type of tire and depends on the type of application. Consult

DO NOT OVERLOAD

Michelin Consumer Care (1-888-622-2306) for assistance

The maximum load that can be put on a truck tire is

in determining the maximum speed for your application.

dependent upon the speed at which the tire will be used.

Exceeding this maximum speed will cause the tire to build

Consult a Michelin Truck Tire dealer or the application data

up excessive heat that can result in sudden tire destruction,

books for complete information on the allowable loads for

property damage, and personal injury. In any case, legal

application. Tires that are loaded beyond their maximum

speed limits and driving conditions should not be exceeded.

allowable loads for the particular application will build up

High speed driving can be dangerous and will likely

excessive heat that may result in sudden tire destruction,

damage your tires.

property damage, and personal injury.

When driving at highway speeds, correct inflation

Some states have enacted “Load Per Inch Width”

pressure is especially important. However, at these speeds,

regulations for the purpose of governing axle weight on

even with correct inflation pressures, a road hazard, for

(primarily) the steering axle of commercial vehicles. These

example, is more difficult to avoid. If contact is made, it

regulations provide a carrying capacity of a certain number

has a greater chance of causing tire damage than at a lower

of pounds per each cross-sectional inch (unloaded) across

speed. Moreover, driving at high speeds decreases the time

the tire’s width. The determination of the tire’s width can

available to avoid accidents and bring your vehicle to a safe

vary from state to state but presumably would be based

stop.

upon either the tire manufacturer’s published technical

Section Four: Extending Tire Life

BALANCE AND RUNOUT

It is customary to check tire and wheel assembly balance if the driver makes a ride complaint. Before removing the tire

and wheel assembly from the vehicle, check for radial and lateral runout. Bent wheels, improper mounting, or flat spotting

can cause excessive runout. If balance is still required, a simple static balance with bubble balancer or a wall mounted axle

bearing and hub type gravity balancer should be sufficient. See Section Ten, Appendix for Runout and Vibration Diagnosis on

Pages 176-178.

Current Technology & Maintenance Council (TMC) limits from TMC RP 214D, Tire/Wheel End Balance and Runout, are listed

in the tables below.

TABLE A:

RECOMMENDED BALANCE AND RUNOUT VALUES FOR DISC WHEELS AND DEMOUNTABLE RIMS

Balance

Radial Runout

Lateral Runout

(See Note 2)

(See Note 3)

Tubeless Steel Disc Wheels

6 oz. max

0.070 inch max

Tubeless Aluminum Disc Wheels

4 oz. max

0.030 inch max

Tubeless Demountable Rims

N/A

0.070 inch max

Steel

(See Note 1)

0.075 inch max

Wide Base Wheels

Aluminum

(See Note 1)

0.030 inch max

Note 1: Refer to the manufacturer’s specifications for balance and runout values.

Note 2: Amount of weight applied to rim to balance individual wheel component.

Note 3: For steel wheels, the area adjacent to the rim butt weld is not considered in runout measurements.

TABLE B:

TIRE/WHEEL ASSEMBLY BALANCE AND RUNOUT LIMITS

19.5

Over The Road

On/Off-Road

Wide Base

Tire Positions

Tire/Wheels

Applications

Tire/Wheels

Maximum total external weight

Steer

12 oz.

14 oz.

16 oz.

22 oz.

correction expressed in ounces of

weight required to correct a rim

Drive/Trailer

16 oz.

18 oz.

20 oz.

26 oz.

diameter per rotating assembly

Steer

0.095”

0.080”

0.110”

0.125”

Lateral runout for

rotating assembly

Drive/Trailer

0.125”

Steer

0.095”

0.080”

0.110”

0.125”

Radial runout

for rotating assembly

Drive/Trailer

0.125”

Note: If tire and wheel assembly is within these limits and ride problem still exists, refer to TMC RP 648, Troubleshooting Ride

Complaints.

58 Section Four: Extending Tire Life

CARE, CLEANING, AND STORAGE

STORAGE

CLEANING AND PROTECTION

All tires should be stored in a cool dry place indoors so

Soap and water is the best solution to cleaning tires.

that there is no danger of water collecting inside them.

If you use a dressing product to “protect” your tires from

Serious problems can occur with tube-type tires when they

aging, use extra care and caution. Tire dressings that

are mounted with water trapped between the tire and tube.

contain petroleum products, alcohol, or silicone will cause

Under pressurization, the liquid can pass through the inner

deterioration and/or cracking and accelerate the aging

liner and into the casing plies. This can result in casing

process. Be sure to refer to the protectant or dressing label

deterioration and sudden tire failure. Most failures of this

contents to confirm that none of these harmful chemicals

nature are due to improper storage. This is a particular

are present.

problem with tube-type tires because of the difficulty in

In many cases, it is not the dressing itself that can be a

detecting the water, which has collected between the tire

problem, but rather the chemical reaction that the product

and tube. When tires are stored, they should be stored in a

can have with the antioxidant in the tire. Heat can make

cool place away from sources of heat and ozone, such as hot

this problem worse. When these same dressing products are

pipes and electric motors. Be sure that surfaces on which

used on a passenger car tire that is replaced every 3 to 4

tires are stored are clean and free from grease, gasoline, or

years, it is rare to see a major problem. In many cases, truck

other substances that could deteriorate the rubber. Tires

tires may last much longer due to higher mileage yields and

exposed to or driven on these substances could be subject

subsequent retread lives, and the chemical reaction takes

to sudden failure.

place over a longer period.

STACKING OF MICHELIN^®X ONE^®TIRES

DIESEL FUEL CONTAMINATION

Stacking MICHELIN^®X One^®tires too high could result

Diesel fuel and other petroleum-based products can

in a safety issue and/or could possibly damage the bottom

cause blistering, swelling, or a spongy condition. Swelling

tires.

is typically seen in the tread, and blistering is typically seen

New MICHELIN^®X One^®tires should never be stacked

on the sidewall. The odor of the petroleum-based product

higher than 3 meters

may be evident. The rubber will also be softer than another

(approximately 10 ft). This

part of the tire with no petrol damage. Generally it may be

will allow the stacking of up

30-40 points softer on the shore hardness gauge. If these

to 6 new tires depending on

conditions are seen or experienced, scrap the tire.

the dimension.

For used and/or damaged

MICHELIN^®X One^®tires

stacking them more than 5 high

may pose a safety concern.

Swellings in the Tread

FLOOD DAMAGE

Tires that have been subjected and exposed to water from

hurricanes, storms, floods, etc. for a substantial amount

of time need to be discarded and not placed in service

on consumer’s vehicles. This applies to both new tires

(unmounted) in inventory as well as those already mounted

and installed on vehicles. Prolonged exposure to moisture

can have a degenerative chemical effect on rubber and lead

to potential failure later in the tire’s life. If any questions

arise, contact Michelin Consumer Care at 1-888-622-2306.

Sidewall Contamination

Section Four: Extending Tire Life

CHAINS*

TIRE DAMAGE RESULTING FROM NON

In order to satisfy legal requirements in many states, you

COMPLIANT RUNFLAT/BEADLOCK DEVICES

may be required to use chains on truck tires. When the

The purpose of this bulletin is to inform end users of

use of chains is required, the following recommendations

the potential for damage from the use of non compliant

should be followed:

devices in tire wheel assemblies.

1. Chains should only be utilized when necessary.

Any device installed inside of a tire/wheel assembly,

The possibility of damage to the tire from the chains will

such as runflat and beadlock devices, must not damage the

increase as driving speed and length of travel increase,

interior surfaces of the tire during normal operation of the

as well as with use on dry pavement. As a general rule,

tire wheel assembly.

chains should be utilized only as long as required, and

Metal, hard plastic, or other non-compliant materials

vehicle speeds should be kept relatively low.

will create damage to the interior surfaces of the tires

2. Since manufacturers have size recommendations

when used in off road and/or reduced inflation pressure

for radial ply tires, no matter what type of chain they

operations of the tire wheel assembly. These damages

manufacture, these size recommendations must be

(as illustrated in the photographs below) will lead to the

adhered to for optimized utility and performance.

tire’s early removal from service, and can result in sudden,

catastrophic failure of the tire.

3. Always be sure to check for proper clearances between

chain and vehicle at the lower 6:00 o’clock position where

the tires deflect due to load. When using tire chains, a

minimum of two inches of space clearance between the

dual assembly and the vehicle is necessary.

4. Also follow closely the mounting instructions and

procedures of the chain manufacturer.

5. Specific chains are available for the MICHELIN^®

X One^®tire product line.

Damage created by these devices is not a warrantable

condition. Further, these damages may cause the tire to

unexpectedly lose it’s capability to retain inflation pressure.

Tire failure may or may not be preceded by bulges, knots,

or blisters on the exterior surfaces of the tire. If a tire

exhibits bulges, knots, or blisters it should be immediately

deflated, removed from service and discarded.

The inclusion of any device or substance inside the air

chamber of a tire/wheel assembly has the potential to

create damage to the tire, please refer to the MICHELIN^®

Truck Tire Operator’s Manual and Limited Warranty

(MWE40021) for a general discussion of what is and is not

* The information provided is for reference only.

covered by the warranty.

Chain-specific questions should be directed to the chains

manufacturer.

For additional information, please contact your local

Michelin sales representative or contact Michelin using the

website at www.michelintruck.com.

60 Section Four: Extending Tire Life

RECOMMENDATIONS FOR THE USE OF DYNAMOMETERS

SEVERE DAMAGE can result in the crown area of radial

truck tires when run on dynamometers for extended

periods. Quite often the damage is internal and not

discovered until after the vehicle has been put back in

service.

In order to avoid the possibility of damaging MICHELIN^®

radial truck tires, adhere to the following time/speed

restrictions and related test parameters. This applies to tire

sizes with bead seat diameters of 19.5, 20, 22, 22.5, 24, and

24.5 inches.

NOTE: The times for the indicated speed in the chart are

not additive.

MAXIMUM TIME (MINUTES)

Speed (mph)*

On 8 5/8”

On 18-20”

Dia. Rollers

62 (Max.)

2.5

3.5

8.5

7.5

105

*Exceeding the legal speed limit is neither recommended nor endorsed.

Note that in the above speed/time table a significant

increase in time is allowed on the 18-20” versus the

8-5/8” diameter roller. For example, at 30 mph time almost

doubles from 7.5 minutes to 14 minutes.

• Allow a two-hour cool-down between tests.

• These limits are for an empty vehicle with tire pressures

as indicated on the tire sidewall for maximum load.

If these times and/or speeds are exceeded,

• Allow a one-hour cool-down after each test before loading

internal damage in the tire could result,

vehicle.

leading ultimately to tire destruction, personal

The maximum allowable center-to-center distance

injury or death.

between the two rollers in contact with a tire is a function

of the sum of tire and roller diameter.

MAX. ROLLER SPACING

Tire Size

Tire O.D.

8-5/8” Dia.

18” Dia.

275/80R22.5 XZE

40.2”

28”

33.5”

This relationship is shown below:

Maximum Roller Spacing

= Tire Diameter + Roller Diameter x

1.15

For example using 8-5 ⁄ 8” diameter:

40.2” + 8.625 x

1.15

= 48.825 x 1.15

= 24.4125” x

1.15

= 28.07”

Section Four: Extending Tire Life

SPINNING

SIPING

Major tire damage can occur in a short period of time

There is no reason to ‘sipe’ new MICHELIN^®tires.

when a tire spins on a surface at high speeds. When the

Michelin incorporates siping as needed in its designs

speed difference between the wheel with good traction

to enhance tire performance. Experience suggests

and the wheel without becomes too great, the tire begins

degradation in tread wear, vehicle ride and handling, and

to disintegrate. This can occur on any slick surface (such

tire durability may be caused by poor or improper tire tread

as ice, mud, and snow) or on a dry surface where there is

siping. Drive tires (M/S) are optimized to provide desirable

a variance in traction. The resulting difference in speed of

traction in dry, wet, snow, and icy conditions. Siping does

the assembly can be as high as 4 times the registered speed

not automatically affect the MICHELIN^®warranty* that

indicated, resulting in tire and/or differential damage on

covers workmanship and material. However, if a tire fails or

the vehicle.

is rendered unserviceable as a result of ‘siping,’ the tire is

not warrantable.

ROTATION

*See warranty for details.

MICHELIN^®radial tires should be rotated when necessary.

If the tires are wearing evenly, there is no need to rotate.

BRANDING

If irregular wear becomes apparent or if the wear rate on

1. The following limits apply when branding MICHELIN^®

the tires is perceptively different (from axle to axle for drive

truck tires using equipment without accurate

tires and side to side for steer tires), then the tires should

temperature control or which may exceed 465°F

be rotated in such a manner as to alleviate the condition.

(240°C). (Hand-held equipment is typically used for this

There is no restriction on criss-cross rotation, including

“HOT BRANDING.”)

directional steer tires that have worn 50% or more of the

a. Brand Temperature/Maximum Depth

original tread.

570°F (300°C) 1/64 inch (0.4 mm)

When rotating tires, the following points should be taken

480°F (250°C) 1/32 inch (0.8 mm)

into consideration:

b. Only brand in the “BRAND TIRE HERE” area.

• The load carried by a particular tire in a particular

2. For equipment capable of “COLD BRANDING,” i.e.,

position. The inside tire of a dual mounting carries more

controlled temperatures below 465°F (240°C), the

load than the outside tire on the same axle.

following restrictions apply:

• Adjacent dual tires should not differ more than 1/4”

a. Temperature

Maximum465°F(240°C)

diameter (4/32” tread wear). If there is a difference in

b. Contact pressure

Maximum 100 psi

tread wear, fit the least worn tire in the outside position.

c. Time of contact

Maximum 1 minute

• Curbing on dual applications often damages tire

d. Character Height

Maximum 1 inch

sidewalls. If so, rotate the wheel and tire to the inner

e. Character Depth

Maximum 0.040 inch (1.0 mm)

wheel position.

f. Location:

• Often it is beneficial to rotate the tires so that irregularly

Circumferentially - in the “BRAND TIRE HERE”

worn tires are moved to a position where they are turning

area.

in a direction opposite the original position.

Radially - in the “BRAND TIRE HERE” area with no

portion of any character extending more than

Rotation procedures such as those recommended by

1 inch above the outline of the area.

vehicle manufacturers and those included in TMC RP 642B,

Total Vehicle Alignment Recommendations for Maximizing

Tire and Alignment Related Component Life may be

followed.

Note Directional Tires: When mounting any new

directional tire, ensure directional arrow points toward

the direction of travel during the original 50% of tread life.

Directional casings that have been removed from service

and retreaded should be considered non-directional tires.

62 Section Four: Extending Tire Life

MAINTAINING THE VEHICLE

Many tire problems can be traced to mechanical

• Alignments should be performed carefully using best

conditions in the vehicle. Therefore, to obtain maximized

alignment practices. (For example, ensuring that

tire performance, vehicles must be properly maintained.

the suspension is at the correct ride height and that

the suspension has been settled out by being moved

MAJOR VEHICLE FACTORS WHICH AFFECT

forwards/backwards, etc.)

TIRE LIFE:

• Alignments should be conducted in the most

representative loading condition and ride height for the

expected usage.

ALIGNMENT

Alignment refers not only to the various angles of the

We therefore recommend referring to TMC RP 642B,

steer axle geometry, but also to the tracking of all axles

Total Vehicle Alignment Recommendations for Maximizing

on a vehicle, including the trailer. The dual purpose of

Tire and Alignment Related Component Life, which has

proper alignment is to minimize tire wear and to maximize

established industry recommended target values for the

predictable vehicle handling and driver control. Toe

alignment of vehicles.

misalignment is the number one cause of steer tire irregular

wear, followed by rear axle skew (parallelism or thrust). One

STEER AXLE GEOMETRY

of the challenges of meeting this goal is that alignments are

Since very few vehicles continue to use Center Point

typically performed on a static, unloaded vehicle sitting on a

Steering, the following recommendations are based on the

level floor. The vehicle then operates over varying contoured

more common Inclined Kingpin Steer Axle Geometry.

surfaces, under loaded conditions, with dynamic forces

acting upon it. Predicting the amount of change between

static/unloaded/level - versus - dynamic/loaded/contoured

is difficult because many variables affect the amount of

change. Variables such as Steering System Compliance (i.e.

“play”) must be considered in making alignment setting

recommendations.

All of these misalignment conditions may exist alone

Inclined Kingpin

or (more likely) in combination with other misalignment

conditions. Sometimes it is these interactions that produce

the outcomes that are especially undesirable. As an

example, a tire running at slightly negative camber may

perform especially badly if it is also subjected to tandem

thrust misalignment. The conceptual understanding for this

TOE

phenomenon is that because of the camber issue, the wear

Toe is typically the most critical alignment condition

burden imposed by the thrust misalignment is not being

affecting steer axle tire wear. The purpose of setting toe at a

shared equally by the entire tread surface. Further, a tire

given specifi

is to allow the tire to run straight during

that is being operated in a misaligned condition may well

normal operating conditions. Too much toe-in results in

transmit forces into the suspension from its interaction with

scrubbing from the outside inward on both tires, and too

the road. Some suspension systems manage those forces

much toe-out results in scrubbing from the inside outward

favorably. Others react in a way that imposes motions in the

on both tires.

tire that are very unfavorable to the tire’s ability to yield a

Total toe is the angle formed by two horizontal lines

favorable wear outcome.

through the planes of two wheels. Toe-in is when the

• Tires that are not operated at a normal (perpendicular)

horizontal lines intersect in front of the wheels or the wheels

angle to the road surface typically produce uneven

are closer together in front than in back. Toe-out is when

tire wear. Tires that are fighting each other (because

the horizontal lines intersect behind the wheels or the

of conflicting alignment operating angles) produce

wheels are closer together in back than in front. Toe-in is

unfavorable and sometimes irregular tire wear. Tires

commonly designated as positive and toe-out as negative.

that are fighting each other due to highly compliant

Steer axle toe is adjustable to reduce wear to the leading

suspension components (compression/extension in the

edge of the tire and also to avoid road wander. Toe is

bushings or joints, or deflection of solid parts) will likely

adjusted in a static, unloaded condition so that the tires will

produce irregular wear forms.

run in a straight line under a dynamic, loaded condition.

Section Four: Extending Tire Life

The toe measurement will probably change from unloaded

TANDEM AXLE PARALLELISM

to loaded condition. The amount of change will vary with

(SKEW - THRUST)

axle manufacturer, axle rating, and steering arm geometry;

Tandem axle parallelism is critical because it can have

but it is still fairly predictable. Front axles on most popular

a detrimental effect on all ten tires on the tractor. Non-

Class 8 long haul tractors will change in the direction of

parallel drive axles tend to push the tractor into a turn in

toe-out about 1/32” (0.8 mm or 0.05 degree) for each 1000

the direction that the axle ends are closest. In order for the

pounds of load increase on the steer axle. Cabover tractors

vehicle to go straight, the driver must correct by steering in

with set-back-front-axles typically experience less steer

the opposite direction. The vehicle can then go straight, but

axle change in load from bobtail to loaded than do other

all ten tires are at an angle to the direction of travel, causing

confi

Wheelbase and fi wheel location are also

scrubbing. Excessive tandem axle non-parallelism is usually

major factors affecting how much load change the steer axle

detected in steer tire wear. If one steer tire is scrubbing from

will experience.

the outside inward and the other steer tire is scrubbing

from the inside outward, then tandem axle alignment is

Toe-in

suspect. A similar pattern can be generated by the driver’s

compensation for a non-lubricated 5th wheel or from a dog

tracking trailer. This should not be confused with a light

level of toe-in on the right front and lighter toe-out wear on

the left front that may be the result of secondary highway

road crown.

Note: Additional consideration would be effects of air ride

suspension systems, rack and pinion systems, and disc air

brakes on steer tire wear.

Tandem Scrub Angle

THRUST ANGLE (TRACKING)

The relationship of the geometric centerline of the vehicle

and the direction that the axle points generates a thrust

angle. Ideally this relationship would result in a

0 degree value when the axle centerline is perpendicular

to the geometric centerline. However, any deviation from

this setting will increasingly cause the vehicle to travel

away from the straight line, causing the tires to “dog track”

and scrub. Tracking to the right generates a positive thrust

angle; tracking to the left creates a negative thrust angle.

A misaligned (dog-tracking) trailer may also be the

cause of steer tire wear.

See Section Ten, Appendix under Conversion Table

on Page 163 for conversion of fractions in inches to

millimeters and degrees. See Section Ten, Appendix under

Alignment on Pages 164-167 for a field method

for verification.

Thrust Angle

(Tracking)

64 Section Four: Extending Tire Life

CAMBER

Drive position: Generally, camber is not a major

contributor to drive axle irregular wear, although combined

Camber is the angle formed by the inward or outward tilt

with dual position toe-in or toe-out may cause the onset of a

of the wheel referenced to a vertical line. Ideal camber may

wear pattern.

vary in different applications and in different axle positions

Trailer position: Trailer axles are typically fabricated

as affected by load distribution (i.e. front axle variance of

from steel tubing with spindles welded to the ends. They are

6,000 to 12,000 pounds, drive axle range of 8,000 to 17,000

usually built straight, so there will be some negative camber

pounds, and trailer axle range of 4,000 to 20,000 pounds).

induced when installed under a trailer. Additional loading of

• Camber is positive when the wheel is tilted outward at the

the trailer will cause additional negative camber. Most

top.

trailer axles deflect to about -0.5 degree camber at 17,000

• Camber is negative when the wheel is tilted inward

pounds per axle loading.

at the top.

Camber can accelerate shoulder wear on dual or single

• Excessive positive camber may cause smooth wear on the

tires. Higher degrees of negative camber will show up on the

outer half of the tire tread.

inner shoulder, and positive camber on the outer shoulder.

• Excessive negative camber may cause wear on the inner

Wide single tires seem more susceptible to camber induced

half of the tread.

wear.

• Camber only causes a noticeable “pull” if on the steer axle

Camber correction by bending axles is NOT

the right and left wheel camber angles are not very close

RECOMMENDED by axle manufactures, nor endorsed by

in magnitude (greater than 1/2 degree).

Michelin. Consult the axle manufacturer if camber is found

• Negative camber can also be a cause of inside shoulder

to be incorrect (outside manufacturer specification).

wear on trailer axle in dual or single configuration.

• A free-rolling tire is more sensitive to camber than a tire

CASTER

twisting or turning under the effect of torque.

Positive (+) caster is the backward tilt at the top of the

• A wide tire with a relatively low aspect ratio is more

kingpin when viewed from the side. Negative (-) caster is the

sensitive to camber than a narrow high aspect ratio tire.

forward tilt at the top of the kingpin when viewed from the

• Generally, the vehicle will pull to the side with the most

side.

amount of positive camber.

The purpose of caster is to provide self-aligning forces on

Camber is often a contributor to wear occurring on the

the steer tires to stabilize the vehicle when driving straight

interior ribs/blocks of the inner dual drive tires and can

down the road under braking, free wheeling, and power

sometimes affect the interior ribs/blocks of the outer dual

conditions.

as well.

Insufficient caster reduces stability and can cause

Steer position: Steer axles (which are generally, but not

wander. Excessive caster increases steering effort and can

always, a forged axle) are designed with static unloaded

cause shimmy. Either of these conditions may also have a

positive camber and tend to produce better tire wear when

detrimental effect on tire wear. Excessive caster beyond the

provided with slightly negative camber due to the effects of

vehicle manufacturer’s specification may result in induced

cornering forces, load transfer, and steering Ackerman

camber causing excessive tire wear, particularly fleets that

geometry, which tend to stress and produce outside

are in local and regional operations. Caster is adjustable

shoulder wear during turning maneuvers. In the interest of

with shims. Adjusting only one side is not recommended.

more even overall wear, it is therefore advantageous to let

Caster on both sides should be equal or not more than 1/2

the wear be biased toward the inside shoulder (via slightly

degree difference. Generally, the vehicle will pull to the side

negative camber) during straight ahead driving.

with the least amount of positive caster.

Positive Camber

Positive Caster +

- Negative Caster

0

Section Four: Extending Tire Life

STEER AXLE SETBACK

TMC RECOMMENDED ALIGNMENT

(STEER AXLE SKEW)

TARGETS

Any measured deviation left (negative) or right (positive)

(Value representing industry-established midpoint.)

away from perpendicular to the centerline of the vehicle is

For more information refer to TMC RP 642B, Total Vehicle

called the setback.

Alignment: Recommendations for Maximizing Tire and

Alignment-Related Component Life.

Alignment

Target Value ⁽²⁾

Specification⁽¹⁾

Steer Axle

+1/16 inches (0.08 degrees, 0.06 inches,

Total Toe

1.5 mm)

Camber

Less than 1/4 degree ⁽³⁾

Caster

Left: +3.5 degrees; Right: +4.0 degrees

Steer Axle Setback

Setback

0 degrees / 0 inches

(Steer Axle Skew)

Drive, Trailer, and Dolly Axles

Thrust (Square)

0 degrees / 0 inches

Scrub (Parallelism)

0 degrees / 0 inches

Lateral Offset

0 inches

(1) All specifications are measured with vehicle in static, unladen condition.

(2) All specifications are stated in inches or degrees (where applicable).

TOE-OUT-ON-TURNS

(3) Camber angle changes normally involve bending the axle beam, which may

(TURNING RADIUS)

void the axle manufacturer’s warranty. If the measurement exceeds this value

consult the vehicle, axle, and/or alignment equipment manufacturer.

Toe-out-on-turns is the difference in the arcs described

by the steering tires in a turn. The purpose is to prevent the

inside tire from scrubbing around a turn since the outside

tire (loaded tire) determines the turning radius of the steer

PERIODIC ALIGNMENT CHECKS

axle. This is the Ackerman Principle. Improper geometry

An aggressive alignment preventative maintenance

results in wheel scrub in turns, which generally appears

program should include the following periodic checks:

as toe wear on the tire. More specifically, Ackerman wear

1. Upon delivery of new vehicles. Even though OEMs

shows itself as a rounded edge radial feather wear across the

make a concerted effort to properly align vehicles at the

tread area of the tire. This angle is more important on a city

factory, shifting and settling can occur during delivery.

vehicle with its many turns than on a line haul unit.

Camber and caster may not change much, but toe and

Ackerman geometry is dependent upon the steering axle

tandem axle parallelism may change sufficiently to set up

track-width and wheel base of a vehicle. When the turning

undesirable tire wear patterns if not corrected upon receipt.

angle or wheel base changes from the original specification,

2. At the first maintenance check. Post break-in alignment

Ackerman is affected.

checks should be done between 15,000-30,000 miles, but no

later than 90 days after the first in-service date. If shifting

Steering Arms

and settling did not occur during delivery, it may occur

during the first few thousand miles of operation. Many

OEMs recommend verification of torque on suspension/

frame components after a few thousand miles of operation.

Basic Ackerman Steering Diagram

A thorough alignment check should be made during this

inspection (after torque verification). Consideration should

be given to different torque requirements on metric and

standard bolts.

Cross Bar

(Tie Rod)

3. When new steer tires are installed or front-end

components are replaced. The steer tires coming out of

Wheel

Base

service can tell a story of good or bad alignment. With this

feedback, an alignment program can continue to improve.

Without feedback, the best an alignment program can do is

stay at its current level.

Rear Axle

4. When tire wear indicates a concern. “Reading” tire

Center of Rotation

wear can help identify alignment issues. Unfortunately,

correcting the alignment does not necessarily correct the

tire wear pattern once an undesirable wear pattern has been

established.

66 Section Four: Extending Tire Life

ALIGNMENT EQUIPMENT

A quick field check procedure is done on elevated, dry

tires, and with a can of spray paint or marker, highlight

Alignment equipment exists that ranges from simple

a section of the tread area around the tire. With a sharp

and inexpensive to sophisticated and costly. One factor

pointed scribe, mark a thin line in the highlighted area

that is common to all types of alignment equipment is

while rotating the tire. Repeat this process on the other

that the person using it is extremely important to the

steer tire. Lower the vehicle on folded plastic bags. Once

resulting tire and vehicle performance! Calibration is

the steer tires are down, bounce the truck to make sure

another critical factor in maintaining the accuracy of the

the suspension is relaxed, and verify that the wheels are

system - follow manufacturers’ recommendations. Some

pointing straight ahead. Then measure from side to side

fleets have obtained excellent results with a good “scribe

between the scribed lines, first rear, then front, with a tape

and trammel bar” and paying strict attention to toe and

measure or a fine-lined toe gauge to determine relative

axle parallelism. Other fleets establish permanent records,

toe. Subtract front from rear: positive result indicates toe-

make adjustments more easily, have more information

in, negative is toe-out. See Section Ten, Appendix under

for trouble-shooting, and obtain excellent results with the

Alignment - Field Method (Pages 166-167) for complete

more expensive equipment. The common ground is that

procedures.

the person using the equipment understands it, uses it

properly, and follows the procedures consistently.

Michelin developed the BibAlignment System as a very

simple, accurate, and repeatable method of establishing

the position of a vehicle’s axles relative to each other.

Through the use of a computer program, the highly

portable and cost-effective BibAlignment System calculates

the corrections necessary to improve the vehicle’s axle

parallelism. It locates the centerline of drive and trailer axles

and projects this centerline to the ground. These points

are measured, recorded, and entered into the computer

program. The resulting data concerning the axle alignment

and recommended corrections may be printed for historical

reference. Contact your local Michelin Representative for

ordering information.

Heavy truck alignment has evolved to a precise science.

The “field check” techniques below may be used to detect

a problem condition but are not recommended for making

adjustments/corrections. Proper alignment equipment

should be used if a decision is made to complete this

service.

FIELD CHECK TECHNIQUES

TOE: This wear on the tread occurs due to the shearing

action created by side forces resulting from excessive

toe-in or toe-out. If the toe is properly set, the steer tires

will feel even and smooth when you move your hand across

the tread surface. If the front tires have excessive toe-in, a

Toe-in

feathering wear will be created. This can be felt very easily

with your hand. The tread will feel smooth when you move

your hand in across the tire, but you will feel a drag or

resistance when you move your hand back out across the

tread. If the front tires have excessive toe-out, the opposite

will be evidenced. The resistance will be felt going across

the tread, with no resistance felt while being withdrawn.

A simple Rule of Thumb to remember when analyzing

steering tire wear is “Smooth In” means Toe-In; “Smooth

Out” means Toe-Out.

Section Four: Extending Tire Life

Parallelism: On a tractor with tandem drive axles,

AXLE PARALLELISM AND TRACKING

the two axles should be parallel to one another. Any

In the straight-ahead position, the rear wheels of a vehicle

deviation from this parallel position will create a

should follow the front wheels in a parallel manner. Wheels

tandem skew or scrub angle. This angle should be no

that are out-of-track can cause excessive tire wear. Failure of

larger than one tenth of a degree. An easy method of

the wheel to track is usually due to the following causes:

checking this angle is to measure the distance between

- Master spring-leaf broken

the ends of the axle hubs on each side of the tractor. The

- Incorrect air spring (bag) height

difference between these two measurements should be

- Worn springs

no larger than 1/8 inch for a tandem tractor/truck and

- Auxiliary leaves broken

no larger than 1/16 inch on a tandem axle trailer. The

- Loose “U” bolts

easiest way of accomplishing this measurement is by

- Incorrect or reverse springs

using a trammel bar. The pointers on the trammel bar

- Bent frame

must fit in the axles’ centering holes on both sides of the

- Locating rods or torque rods improperly adjusted

vehicle.

- Locating rod or torque rod bushings worn excessively

For example, if the ends of the drive axles on the left

Failure of the wheels to track is usually quite visible when

side of the vehicle are closer together than the axle ends

one follows the vehicle on the highway. It is possible that, due

on the right side, this will cause the vehicle to pull or

to one of the above causes, no uneven wear manifests itself on

drift to the left.

the rear tires, but an uneven wear pattern may show itself on

the front tires. This is because rear tires may push the vehicle

off course and give some toe-out-on-turns in the straight-

ahead position to the front tires. Hence, the driver makes

a correction to offset the steering action caused by the rear

wheels.

If the rear axle of a vehicle is not at right angles to the

chassis centerline, the front tires are affected, showing

misaligned wear. In the diagram below, the position of the rear

axle of the vehicle has been altered because of a weakened

left side spring - so that the rear axle on the left side is further

from the front axle than the rear axle on the right side.

In this illustration of a 4x2 configuration, the angle of the

rear axle causes its wheels to point to the left side so that the

rear end of the vehicle is, in fact, self-steered in that direction.

The vehicle would then steer itself to the right - unless the

driver takes corrective action. If the driver wishes to travel

straight ahead, he will naturally compensate by turning his

steering wheel. This action introduces a turning moment as

if the vehicle were making a turn although it is moving in a

straight line due to the toe-like posture of the front wheels.

It is more difficult to identify this concept with additional

drive axles and the placement of movable 5th wheels. For this

Tandem Scrub Angle

reason, the onset of misalignment wear patterns on the front

tires may be apparent, even though the lateral forces may be

slight and the front wheel alignment settings may be correct.

Top View

Inside

Wear

Springs

Outside

Wear

Vehicle Pulls to Right

68 Section Four: Extending Tire Life

HOW TO CHECK AXLE PARALLELISM AND TRACKING:

With the vehicle on a flat surface and with the suspension in a relaxed position, select two points on the front and rear

axles. These two points on each axle must be equal distance from the chassis center (e.g., at the point where the springs meet

the axles). Using a plumb line, mark four points on the ground, move the vehicle away, and measure the distance between

the marks as shown on the diagram.

A more detailed field type procedure is recommended by Michelin and can be found in the Section Ten, Appendix under

Alignment - Field Method (Pages 166-167).

For Truck/Tractor: The Technology and Maintenance

For Trailers: The Truck Trailer Manufacturers

Council recommends no more than 1/8 inch between axle

Association (TTMA) recommends no more than 1/16 inch

ends. If AD = BC and DE = CF, the axles are parallel.

between axle ends and 1/8 inch maximum from the trailer

If X = X’ and Y = Y’, the wheels are symmetrical or

kingpin to the lead axle ends. If AD = BC and CE = DE, the

tracking.

axles are parallel and symmetrical. (Reference: TTMA RP

No. 71 Trailer Axle Alignment.)

Section Four: Extending Tire Life

TIRE WEAR PATTERNS DUE TO MISALIGNMENT

It should be noted that some wear patterns might be from multiple causes. Additional information may be obtained

in the TMC RP 216C/219C, Radial Tire Conditions Analysis Guide and www.michelintruck.com/reference-materials/

videos/#/maintenance-and-training about the “Fundamentals of Tire Wear” and “Scrap Tire Analysis.”

Toe Wear - The typical wear pattern that develops from

Free Rolling Wear - Wear at the edge of a rib

excessive toe is a feather edged scuff across the crown.

circumferentially, which may or may not affect the entire

Excessive toe is usually seen on both steer tires.

rib widths. Intermittent side forces due to wheel assembly

instability cause contact pressure variations, resulting in

this type of wear. Generally, due to excessive looseness

in the suspension and/or steering components, this is

also found in slow wearing positions at high mileage.

Insufficient caster and excessive lateral tire/wheel runout

also are contributing factors.

Toe Wear

Free Rolling Wear

Toe Wear

Free Rolling Wear

70 Section Four: Extending Tire Life

Flat Spotting Wear - Localized wear across the tread

Diagonal Wear - Localized wear diagonally across the

width. Causes include brake lock, brake imbalance, out of

tread width. Side forces imposed by a combination of

round brake drums, axle hop, or skip. A tire being parked

toe and camber create diagonal stress in the footprint of

on a surface containing hydrocarbon oils, chemicals, and

the tire. Localized wear patterns tend to follow this same

solvents can also cause this type of wear pattern. The

direction creating diagonal wear. For steer positions,

affected area of the tread will wear more rapidly, leaving a

causes include excessive toe combined with tandem

flat spot.

drive axle misalignment, incorrect steering angle in turns,

worn parts, and/or excessive camber setting. For trailer

positions, causes include tandem trailer misalignment,

negative camber, and loose or worn components.

Diagonal Wear

Flat Spotting - Drive

Flat Spotting - Trailer

Diagonal Wear

72 Section Four: Extending Tire Life

IRREGULAR TIRE WEAR

TRACTOR:

Heel-Toe

Appearance:

Drive-lugs around the tire worn high to low from the front

to back edge on tread of tire.

Probable Cause:

High torque, pickup and delivery operations (P&D) plus

mountainous terrain, high braking operations.

Analysis/Correction:

Drive tires should be rotated, front to rear; cross rotation is

permitted, but will accelerate wear and can reduce removal

Inset: Notice

mileages. With the MICHELIN^®X One^®tire, since there are

appearance of

no dual pressure differences, heel and toe pattern should

shoulder-scrub

on side of tread-

clear itself up @ 1/3 worn.

blocks inner/outer

shoulders.

Center Wear

Appearance:

Tire wears more rapidly in the center of the tread, than in

the shoulders.

Probable Cause:

LTL (Less than Truckload) operation + high torque,

incorrect pressure.

Analysis/Correction:

Five tread depths should be taken in the drive position,

allowing one to recognize wear conditions.

Correction of drive-axle pressure will reduce the wear

pattern and enhance tire mileage.

13/32” 14/32”

11/32”

14/32” 13/32”

River Wear Only

Appearance:

Tire exhibits circumferential wear along the rib-edges next

to the major shoulder tread-ribs.

Probable Cause:

Characteristic of slow wear-rate of radial tires.

Analysis/Correction:

None, river wear should not be of concern.

Section Four: Extending Tire Life

TRAILER:

Step-Shoulder/Localized Wear

Shoulder Cupping

Appearance:

Tire exhibits step-down wear on one or both

shoulders or localized cupped out areas.

Probable Cause:

Incorrect pressure, damaged/bent trailer-axle,

incorrect camber setting, alignment issue, LTL

(Less than Truckload) operation, suspension

compliance.

Analysis/Correction:

Review tire application with tire manufacturer;

review inflation maintenance procedures.

Check trailer alignment for bent or worn parts,

or consult trailer OE.

Left Front Trailer Position

(Original)

(Rotated)

Trailer Rotation:

Irregular wear on the inside shoulder of trailer tires can be rectified by flipping the tire on the wheel, where the inner

shoulder becomes the outside shoulder. Criss-cross rotation may also be helpful depending upon 1st and 2nd trailer axle

wear-rates.

Brake Skid

Appearance:

A tire with brake drag is characterized by localized

abrasion or flat spot if severe. If left in service, it may

continue to grow across the face of the tread.

Probable Cause:

Tractor/trailer moved prior to system pressure

building up sufficiently to release parking brakes:

resulting in dragging the tires or driver over-using

hand or trailer brake.

Analysis/Correction:

Review driver tractor/trailer hook-up and departure instructions. The fleet yard mule driver can be a factor. If they are

in a hurry to move trailers, they may pull away before the pressure has built up sufficiently to release the brakes. If the

flat spotting is minor, leave the tire in service. If tire induces vibration, has exposed steel or is lower than the minimum

required tread depth, remove the tire from service. Even vehicles equipped with anti-lock brake systems (ABS) can

experience flat spotting, depending on the number and placement of sensors and modulators used.

74 Section Four: Extending Tire Life

BRAKING SYSTEMS AND ISSUES

Air brake issues as they apply to tire wear and damages

can result from imbalance or component concerns.

Distorted, brittle, and/or discolored rubber in the bead

area are signs of the “outside to inside” breakdown of

rubber products as a result of seating on a wheel surface,

which is heated to a temperature beyond the limit that

the rubber products can tolerate. This damage starts at

a temperature in the mid-200 degree Fahrenheit range,

with accelerated damage occurring above the 300 degree

Fahrenheit range.

1. Brake imbalance can be the result of the air system,

Brake Heat

including valves, not actuating the brakes simultaneously.

This may be the result of dirt, leaks, and/or valve cracking

pressure. In a tractor/trailer combination, the more rapid

brake application time now being used (up to twice as

fast as pre FMVSS*-121 systems) can result in a brake

imbalance due to combinations of old tractors with new

trailers or new tractors with old trailers.

2.Component situations, such as out-of-round brake

drums or unevenly worn brake shoes, also result in tires

acquiring odd wear and flat spots.

3.Another source of brake imbalance is the improperly

adjusted slack adjuster. Any of these brake imbalance

situations can result in one or more wheel positions

Brake Heat

locking up and flat spotting the tires.

4.Brake drums with balance weights thrown may result

in ride disturbance.

5. Brake lock (flat spots) conditions may be evidence of

deficiency in the Anti-Lock Brake System.

*FMVSS - Federal Motor Vehicle Safety Standards

SUMMARY OF TIRE ISSUES DUE

TO BRAKES

Problem

Possible Causes

Result

1. Overuse on down

grades due to

Brake Lock

improper gear.

Bead damage

2. Brake dragging due

to the tire

to mis-adjustment of

ranging from

wheel bearings.

simple distortion

3. Repeated stops

Brake Heat

to complete

without cooling time.

unwrapping of

4. Improper adjustment

the casing from

or braking balance

the bead wire.

leads to excessive

amount of braking in

one or more wheel

positions.

1. Out-of-round brake

assembly.

Flat spots and

2. Slow release valves.

Lock Up

odd wear.

3. Mis-adjustment, slack

adjusters.

4. Brake drum runout.

Brake Lock

Section Four: Extending Tire Life

BRAKE HEAT OVERVIEW

Brake temperatures on trucks often reach very high

temperatures. Brake drums can reach temperatures of

600°F or more and are in very close proximity to the wheels.

This heat can be easily transferred to the wheels and tires.

Brake drum heat is transferred to the wheel primarily

through radiation and convection. The hot brake drum

radiates heat in all directions to the wheel. In addition,

the drum heats the air between the drum and the wheel.

The heated air rises and transfers additional heat energy

to the wheel through convection. Much of the heat is

transferred to the wheel in the bead mounting area due

to its close proximity to the brake drum. The wheel then

Brake Lock on Ice

directly conducts heat to the tire bead resulting in elevated

temperatures in the tire bead area.

Excessive bead heat can affect tire life in many truck

tire applications. Vehicles in urban and refuse service are

most commonly associated with bead heat issues, but any

application that experiences hard braking can be affected.

Brake Lock on Grooved Payment

Duals - Close to Brake Drum

CASING LIFE vs BEAD TEMPERATURE

400

350

300

250

200

150

100

1,000

10,000

Casing Life (hr)

76 Section Four: Extending Tire Life

Results of bead heat:

The second stage occurs when the rubber in the bead

1. Immediate failure: In some cases, after periods of

area starts to split or crack, indicating that the steel casing

hard braking where brake drums reach very high

plies are starting to unwrap.

temperature (in excess of 600°F), immediate failure can

occur. This normally occurs when a truck is brought

to a stop for a period of time with very high brake

temperatures. Often this occurs when an over the road

truck stops at a truck ramp at the bottom of a long

descent. As the heat rises from the brake drum, there

is excessive heat buildup in the portion of the tire bead

directly above the brake drum (inner bead of inside

dual). The high temperature can cause a breakdown of

the rubber products in the bead area and allow

the steel body cables to unwrap from the bead. This

could result in a rapid tire pressure loss occurrence.

This phenomenon is also common in urban and refuse

fleets when the driver stops for a break after a period of

hard braking.

2nd Stage - Bead Splitting From Heat

2.Degradation of the casing: Heat is a tire’s worst

enemy! A tire subjected to high heat conditions over

The third stage is when the casing ply fully unwraps

an extended period of time will experience accelerated

from the bead. In extreme cases the casing ply unwraps

degradation of the rubber products. The degradation

from the bead all the way around the tire. At this point the

may result in a blowout during operation, or it may

tire completely separates from the bead wire. The bead

render the casing unsuitable for retread. The graph on

wire can entangle itself around the axle if this type

the previous page demonstrates how operating with

of separation occurs.

bead temperatures in excess of 200°F will significantly

reduce your casing life.

Bead damage as a result of brake heat is recognizable

in 3 stages of severity. In the first stage, the bead starts

to turn inward. This can be visibly identified on the tire

when it is dismounted. A straight edge placed across the

beads from one bead to the other no longer rests on the

bead point, but now rests closer to the bead bearing area.

3rd Stage - Partial Unwrapping of the Casing Ply

1st Stage - Turning of the Bead

3rd Stage - Complete Unwrapping of the Casing Ply

Section Four: Extending Tire Life

5TH WHEEL MAINTENANCE AND

WHEEL BEARING AND HUB INSPECTION

PLACEMENT

Driver pre-trip: Visually inspect each wheel end for

Placement of the 5th wheel can be determined by

loose, damaged or missing fasteners or hubcaps. Look for

the need to properly distribute the load over the drive

oil and lubricant leaks and oil level and condition.

tandems and the steer axle for legal loads. It can also be

Inspect in conjunction with preventative maintenance

placed to lengthen or shorten the overall length of the

schedule: With axle raised and supported, remove tire

tractor-trailer unit. However, with sliding 5th wheels, many

and wheel assembly, check for above items. Use a magnet

drivers place the 5th wheel to give the smoothest ride and

through the hubcab fill plug to detect any metallic materials

easiest steering. The placement and movement of the 5th

in the lubricant.

wheel can change the tire loading substantially, causing

12 month or 100,000 mile inspection: In addition to

tire overload or tire underload conditions. Insufficient

above items, check wheel end play (should be between

lubrication of the 5th wheel is a major cause of poor vehicle

0.001 and 0.005 inch). If at 0.000 or greater than 0.005 inch,

handling. Distortion of the 5th wheel plate will cause a

adjustment is necessary. Service accordingly following

similar condition to lack of lubrication and dog tracking of

manufacturer recommended procedures.

the trailer.

5 year or 500,000 mile service (frequency dependent on

service application): Follow manufactures recommended

procedures for removal/reassembly of hub assembly and

service of manually adjusted or pre-adjusted bearings and

Anti-Lock Braking System.

SUSPENSIONS

Forming the link between the truck and the tire, the

suspension system provides a very important contribution

to tire performance. The suspension must support the load

Insufficient Lubrication

and maintain the tire in the proper operating position on

the road. If the suspension is in good operating order, the

tires will track straight and be evenly loaded. This promotes

slow, even wear and low tire cost-per-mile.

Different truck manufacturers use different suspension

systems. Some of these are adjustable for making minor

changes, and some are not adjustable. All suspensions have

parts that move and are, therefore, subject to wear. Worn

or broken suspension parts are one of the main causes of

Proper Amount of Lubrication

irregular tire wear and handling concerns. (Ref. - Quick

checks for system and suspension faults on Pages 79-80.)

A 5th wheel in the most rearward position, combined

When observing irregular wear on a tire, first check for worn

with stiff front axle springs, can cause the front tire to

or broken front and rear suspension parts.

periodically unload, leading to vehicle shimmy and irregular

tire wear. Vehicle manufacturers usually recommend a 5th

AIR SUSPENSION SYSTEMS

wheel placement that results in payload transfer to the front

As vehicle manufacturers move away from multiple

axle. Improper front axle load distribution can adversely

springs, there is an increased need to dampen the effect

affect braking and handling, which can result in excessive

of road shock. Air suspension systems consist of fasteners

tire wear.

and bushings with various components such as air springs,

air or gas shocks, torque arms, air lines and valves held

together by nuts and bolts. Day to day operations generate

a constant twisting movement to all these parts and greater

awareness and maintenance diligence should be paid to

wear and proper torque to ensure proper performance of

the system and the effect this has on tire life. All torque

values should be verified to manufacturer’s specification,

and new shock absorbers should be considered when

installing new tires so as to maximize tire life. Shock

Distortion of the 5th Wheel

absorbers used on air ride suspensions should typically

78 Section Four: Extending Tire Life

provide effective dampening control for 150,000 miles

manufacturer instructions. Pivot Bushing inspection

of on-highway operations (100,000 miles for vocational

should consist of taking measurements before disassembly

applications). Refer to TMC RP 643, Air-Ride Suspension

to complete your inspection, complying with warranty*

Maintenance Guidelines on air suspension systems.

procedures, and replace the bushing if cracks or complete

Routine inspection of trailer air suspensions should

separation of the rubber is present.

be scheduled to inspect connectors and bushings per

* See warranty for details.

QUICK CHECKS FOR REAR SUSPENSION FAULTS

ISSUE

POSSIBLE CAUSE

• Improperly installed mounts and/or bushings

Shock Absorbers

• Damaged or leaking shocks

• Not torqued to specification

U-Bolts

• Improperly torqued due to mismatched metric and standard bolts with different specifications

• Loose attaching bolts

• Worn bushings in shocks, spring hangers, torque rods

• Missing alignment adjusting shims

Suspension System

• Excessive drive axle offset

• Excessive sway bar movement

• Worn hanger pins allowing axle movement

• Improperly functioning ride height control system

• Master or auxiliary spring-leaf broken

• Incorrectly installed springs

• Worn springs

Wheels out of Track

• Loose U-bolts

(Dog Tracking)

• Bent frame

• Torque rods improperly adjusted

• Torque rod bushings worn excessively

• Incorrect parallelism, skew, scrub

Alignment

• Dual position toe-in or out (induced toe value at each drive wheel)

• Camber

• Wheel bearings loose or damaged

Miscellaneous

• 5th wheel placement

• 5th wheel and chassis lubrication

QUICK CHECKS FOR TRAILER SYSTEM FAULTS

QUICK CHECKS WOULD INCLUDE:

• Verify OEM alignment after 1,000-3,000 in-service miles

• Alignment (induced toe value at each dual position,

• Verify rails are straight

negative camber, parallelism)

• Loose or missing fasteners, look for elongated holes

• Worn or loose wheel bearings

• Damaged or bent brackets

• Brake imbalance

• Look for wear at u-bolts and springs - signs of movement

• Slow release of trailer brake systems

• Look for signs of rust at track rod to indicate movement

• Operational conditions, high scrub application

• Inspect torque arm clamp nuts and bolts for proper torque

• Tire scrub/dragging at dock deliveries

(check threads to see if stripped)

(commonly called Dock Walk)

• Verify spring beams are centered on hanger; if not,

• Pressure maintenance (improper for operation)

check alignment

• Overloaded/underinflated, high speed empty hauls

• Slider assembly movement, loose attaching bolts,

• Mismatched pressure by dual position or axle

u-bolt torque

• Mismatched tread depth/tire design by dual position

• Air-ride suspension movement

• Improper tread depth for application/operation

• Insufficient lubrication

• New steer tire(s) mixed in trailer positions

• Worn shocks or springs

• Tire rotated from steer or drive with existing wear

• Bushings cracked or separated (inspect per manufacturer

• Improper tire assembly mounting

procedures)

• Driving habits, improper use of trailer brakes

Section Four: Extending Tire Life

QUICK CHECKS FOR FRONT SUSPENSION FAULTS

ISSUE

POSSIBLE CAUSE

• Loose or worn ball joints

• Loose front suspension attaching bolts

Thumps and Knocks from Front Suspension

• Missing adjusting shims

• Loose shock absorber mountings

• Check for worn or damaged spring eye bushings

• Loose attaching bolts

Groans or Creaks from Front Suspension

• Bent control arm or steering knuckle

• Worn kingpins or kingpin bushings

Squeaks from Front Suspension

• Coil spring rubbing on seat

• Worn tie rod ends

• Worn kingpins or kingpin bushings

• Loose suspension attaching bolts

Wander or Shimmy

• Weak shock absorbers

• Weak front springs

• Incorrect front end alignment

• Steering shaft U joint

• Weak front springs

Frequent Bottoming of Suspension on Bumps

• Weak shock absorbers

Front End Sag

• Weak front springs

• Incorrect front wheel alignment

• Worn kingpins or kingpin bushings

• Loose front suspension attaching bolts

• Weak shock absorbers

• Weak front springs

Irregular or Excessive Tire Wear

• Bent control arm or steering knuckle

• Worn tie rod ends

• Excessive steering system compliance

• Steering shaft U joint

• Loose wheel bearing

• Weak shock absorbers

Floating, Wallowing, and Poor Recovery from Bumps

• Weak front springs

• Worn kingpins or kingpin bushings

• Loose suspension attaching bolts

• Bent control arm or steering knuckle

Pulling to One Side While Braking

• Weak front springs

• Weak shock absorbers

• Loose wheel bearing

• Brake adjustment

• Damaged shock absorbers

• Weak shock absorbers

Rough Ride and Excessive Road Shock

• Weak springs

• Control arm shaft bushings need lubrication

• Worn kingpins or kingpin bushings

• Loose suspension attaching bolts

• Worn control arm shaft bushings

Excessive Steering Play

• Weak front springs

• Worn tie rod ends

• Steering shaft U joint

• Loose wheel bearing

• Worn kingpins or kingpin bushings

• Loose suspension attaching bolts

• Worn control arm shaft bushings

Pulls To One Side

• Weak front springs

• Incorrect wheel or axle alignment

• Bent control arm or steering knuckle

• Worn kingpins or kingpin bushings

Hard Steering

• Incorrect front end alignment

• Bent control arm or steering knuckle

80 Section Four: Extending Tire Life

SECTION FIVE

MICHELIN

^®X One® Tires

Section Five

MICHELIN^®X One^®Tires

81-112

DRIVER INFORMATION

AXLES AND WHEEL ENDS

Axle Identification Tags

Load Ratings

SPINDLES

OVERALL VEHICLE TRACK AND WIDTH

Use of Outset Wheels with MICHELIN^®X One^®Tires

Axles Track Widths

Vehicle Track

BEARINGS

ENGINE COMPUTERS / FUEL ECONOMY

AIR INFLATION AND PRESSURE MONITORING SYSTEMS

The Use of Pressure Monitoring and Inflation Systems

with MICHELIN^®Truck Tires

Automated Tire Inflation Systems (ATIS) on Trailers

and Missed Nail Holes

TRUCK TYPE BY WEIGHT CLASS

Recommendation for use of MICHELIN^®X One^®Tires

in 4x2 Applications

TIRE PRESSURE MAINTENANCE PRACTICES

Comparative MICHELIN^®X One^®Tire Sizes Wheel

MICHELIN^®X One^®Tire Mounting Instructions

HEAT STUDY

Brake Heat Overview

Brake Heat Evaluation: MICHELIN^®X One^®Tires vs Duals

TIME LABOR STUDY - MICHELIN^®X ONE^®TIRES VS

DUAL ASSEMBLY

100-101

Torque

RETREAD AND REPAIR RECOMMENDATIONS

102-106

Repair Recommendations

Retread Recommendations

Chains

Gear Ratio

Footprint Comparisons to Dual Tire Fitments

OPERATION AND HANDLING

107-112

Over-Steer

Under-Steer

Cornering Stiffness for Different Tires

Hydroplaning

Rollover Threshold

Jack-Knife

Rapid Tire Pressure Loss Procedure

Traction

Chains

Stopping Distances

Limping Home

State and Local Regulations

Section Five: MICHELIN^®X One^®Tires

DRIVER INFORMATION

Pressure Maintenance

Drivers have commented that an under-inflated MICHELIN^®X One^®tire is more likely to be

detected with a simple visual inspection than dual tires. However, pressure is difficult to gauge

visually even for the most experienced driver.

s Do use a properly calibrated gauge when verifying

the pressure of a MICHELIN^®X One^®tire.

s Don’t rely on the appearance of the tire.

s Do remove and inspect any tire found to be 20% below

the recommended pressure.

Failure to do so may cause tire failure.

Vehicle Handling

Drivers have commented that the wide, stable footprint of the MICHELIN^®X One^®tire

can provide the feel of a much more stable truck compared to traditional dual tires.

However, while most MICHELIN^®X One^®tire fitments allow the track of the tractor and

trailer to be widened, the vehicle’s behavior in curves (on ramps or off ramps) is still subject

to roll-over at excessive speeds.

s Don’t let the outstanding handling of MICHELIN^®X One^®

tires give you a false sense of stability in curves.

s Do respect all posted speed limits regardless

of tire fitment.

Failure to do so may cause vehicle to tip.

Rapid Tire Pressure Loss Techniques

Extensive testing has shown that a rapid tire pressure loss on a MICHELIN^®X One^®tire will not

compromise the stability and behavior of the vehicle. However, with one tire on each axle end,

the loss of pressure will allow the wheel and axle end to drop and possibly contact the road

surface.

s Don’t try to “limp home” or continue to run on a flat tire.

Limping is a direct CSA (Comprehensive Safety Analysis) violation.

s Do down shift or use the trailer brake (when appropriate)

to avoid tire/wheel assembly lock-up.

s Do release the brakes intermittently as you slow down

to allow some rotation of the assembly.

Failure to do so may cause irreparable damage to the

tire, wheel, axle components, and vehicle.

82 Section Five: MICHELIN^®X One^®Tires

AXLES AND WHEEL ENDS

AXLE IDENTIFICATION TAGS

There are primarily three manufacturers of drive and trailer axles for the long haul highway market.

Meritor^®, DANA, and Hendrickson all supply trailer axles, while only DANA and Meritor^®supply drive axles.

Meritor^®- DRIVE AXLE IDENTIFICATION

AXLE IDENTIFICATION TAG INFORMATION

Model No.

Customer No.

Serial No.

Plant

Ratio

Identification Tag

Axle Housing

Location of the identification tag, or stamp number,

Identification Tag

for the axles. Location is determined from the left

driver side looking toward the front of the vehicle.

A - Front engine drive - Right rear, next to cover

B - Rear engine drive - Left or right rear, next to

drive unit

Axle

Carrier

Identification Tag

Meritor^®- TRAILER AXLE IDENTIFICATION

Beam Type

Beam Capacity

T = Tubular

lbs

N = 22,500

10,206

P = 22,500/25,000/30,000

10,206/11,340/13,608

Q = 25,000/30,000

11,340/13,608

R = 22,500/25,000

10,206/11,340

T N

6 7 0 Q

2 0 2 0

Modification

Brake Width

1 = Single Wheel

1 = 10” (25 cm)

2 = Intermodal

6 = 6” (15 cm)

3 = Bolted on Brakes

7 = 7” or 7.5” (18-19 cm)

4 = Manual Bearing Adjustment

9 = 8” (20 cm)

6 = Positive Bearing Adjustment

0 = No Brakes

8 = 0.625” Nominal Wall Axle

NOTE: The graphic provided is for reference only. Axle specific questions should be directed to the axle manufacturer.

Section Five: MICHELIN^®X One^®Tires

DANA - DRIVE AXLE IDENTIFICATION

Parts Identification

Axle Housing

Axle Shaft

1 - Axle Housing

2 - Axle Shaft Part Number

S 26 - 1 7 0 D

Options

D - Dual Drive Forward Axle

B - Bus/On-Center Bowl

with Inter-axle Differential

C - Controlled Traction

G - Single Rear Axle (Global)

D - Differential Lock

R - Dual Drive Rear Axle

Design Level

E - High Entry Single

S - Single Rear Axle (N.A.)

F - Flipped/Rolled Over

T - Tridem Configuration

H - Heavy Wall

Head Assembly Series

I - Integral Brake

Gear Type

L - Limited Slip

1 - Standard Single Reduction

GAW Rating

N - No Spin Differential

2 - Dual Range

X 1000 lbs. (N.A.)

O - Offset Change

5 - Helical Reduction

x 1 TN (Global)

P - Lube Pump

6 - Helical Overdrive

R - Retarder Ready

U - Unitized Spindle

W - Wide Track Housing

DANA - AXLE IDENTIFICATION

Identification Tag

0 00 000 0000

EST-225 J

Spindle Code

Serial Number

J - “J” Trailer Spindle

D - “D” Trailer Spindle

Julian Date

P - “P” Trailer Spindle

Year

Tube Capacity Rating

(x 100 lbs.)

Manufacturer’s Location

Brake Code

T - 16 1/2” x 7” Brake

R - 15” x 8 5/8” Brake

Extended Service Brake

Eaton

NOTE: The graphic provided is for reference only. Axle specific questions should be directed to the axle manufacturer.

84 Section Five: MICHELIN^®X One^®Tires

HENDRICKSON - TRAILER AXLE IDENTIFICATION

Model: VANTRAAX^®.5836

Description: HKANT40K 165RH 77USHD MA X7SH

U - HUS Spindle

Model: VANTRAAX^®.2157

Description: HKAT 50K 16RH 71NST QD X7SHD

N - N Spindle

Model: INTRAAX^®.2597

Description: AAT 23K 14RH C77USST 7S

U - HUS Spindle

Model: INTRAAX^®.3598

Description: AAL 30K 9RH 71PST

P - P Spindle

NOTE: The graphic provided is for reference only. Axle specific questions should be directed to the axle manufacturer.

LOAD RATINGS

Prior to contacting the axle manufacturer, you should

The load/capacity rating of a given axle is determined

consult the axle identification tag to obtain the following

by the axle housing strength, bearing capacity, and hub

information:

- Axle Manufacturer

capacity. For some ultra-lightweight axles, the reduced

axle housing thickness may be the weak link, but usually

- Manufacturer’s Model #

it is the bearings or hub that will be the limiting factor.

- Axle Serial Number

- Axle Capacity

These axles and components are typically designed

undertheassumptionthattheactionline of the tire load

Information on actual operational axle loading

(as opposed to rated load) is crucial, since the axle

is located between the two bearings. This is typically

manufacturer may recommend de-rating the axle below

found with dual tire mounting or with single tires with

very low outset wheels with the axle rating being similarly

the vehicle manufacturer’s GAWR (Gross Axle Weight

determined.

Rating).

With this data in hand, contact the particular axle

If wheels with greater outset are used, the resulting

cantilever loading may require lower ratings for some

manufacturer at the numbers listed below for specific

application information.

of the axle components. The level of de-rating and

ArvinMeritor^™- www.meritor.com

the implications thereof are determined by the axle

manufacturer, so they should be consulted prior to

DANA - www.dana.com

fitment of outset single wheels.

Hendrickson - www.hendrickson-intl.com

Section Five: MICHELIN^®X One^®Tires

SPINDLES

There are three main spindle types you will encounter

The best way to determine what type of spindle may be

when retrofi

MICHELIN^®X One^®tires: “N”, “P”, and “R”.

fitted to a given axle is to reference the axle ID data plate

affixed to the axle or the suspension ID tag as described

N-TYPE SPINDLES (TAPERED)

on Pages 83-85. The following photos display actual tag

N-type spindles are tapered to the outboard end and

placements.

utilize a smaller outboard bearing and a larger inboard

bearing.

Outer bearing smaller than inner bearing.

Tag Placement

P-TYPE SPINDLES (STRAIGHT)

P-type is a parallel spindle design (straight shaft) and

utilizes the same sized bearings inboard and outboard.

Tag Placement

This is generally a heavier duty axle end.

Outer and inner bearings the same size.

A quick rule of thumb is to measure the hub cap.

N-type is usually ~4.5” and the P-type is usually ~6.0”.

R-TYPE SPINDLES

R-type is a drive axle spindle configuration. The R-type

N-Type Spindle

spindle for drive axles is typically straight with bearings of

nearly the same size.

P-Type Spindle

86 Section Five: MICHELIN^®X One^®Tires

OVERALL VEHICLE TRACK AND WIDTH

Vehicle track width is determinedbytakingthe axle

This method also works well for determining the track

track width and adding or subtracting the left and right

width on dual tires.

wheel outsets or insets respectively.

Without changing the width of your axle, your track width

can change depending on your wheel outset or inset.

Outset: The lateral distance from the wheel centerline to

the mounting surface of the disc.

Outset places the wheel centerline outboard of the

mounting (hub face) surface.

Inset places the wheel centerline inboard of the mounting

(hubface) surface or over the axle.

Aneasywaytomeasurethisyourselfis to start on the

left side of the axle, hooking your tape on the outside

edge of the tread. Stretch the tape to the right side of the

If 2” outset wheels are mounted backwards,

axle andmeasureto the inside edge of the tread.

this will significantly reduce track width and

could affect vehicle stability possibly leading

to an accident, injury or death.

Disc Face

Outboard

Inboard

Take the measurement where the tape measure crosses

the left edge of the right side tire’s tread.

The measurement you have just taken is your vehicle’s

track width. Simply put, it is the center to center distance

OUTSET

of your tires.

Overall width of axle assembly is determined by

77.5"

measuring the outer tire sidewall to outer tire sidewall. This

77.5"

measurement is takenat the top of the tire’s sidewall to

avoid measuring the sidewall deflection. The Federal DOT

(Department of Transportation) maximum allowed is 102

For a close approximation, clip the end of the tape

measure on the left tire’s outside sidewall and pull the tape

to the outer sidewall of the outer tire on the opposite side.

Dual Tires

Ifyourmeasurementis close to 102”, then amore precise

method will be required.

80.5"

MICHELIN^®X One^®Tires

Section Five: MICHELIN^®X One^®Tires

USE OF OUTSET WHEELS WITH

AXLES TRACK WIDTHS

MICHELIN^®X ONE^®TIRES

Three standard trailer axle track widths are available.

The MICHELIN^®X One^®tires (445/50R22.5 and

They are 71.5”, 77.5”, and 83.5”. A typical tandem drive

455/55R22.5)require the use of 14.00 x 22.5” wheels.

axle track width is approximately 72”. Check with the axle

Themajority view of the wheels currently offered today

manufacturers for other sized options.

have a 2” outset.

Some axle and hub manufacturers have clarified and

Axle width is measured from spindle end to spindle end

confirmed their position concerning the use of such wheels

(the two widest points).

with their respective components. While the position of

Axle track is a center to center distance between the dual

the component manufacturers is not totally consistent,

or center of single tire to center of single tire.

the majority view of the wheel currently offered have a 2”

outset.

71.5” is a standard axle track width found on bulk and

Truck and trailer manufacturers may have different

liquid tankers.

specifications. For optimum track width, stability, and

77.5” is a standard axle track width for 102” wide trailers.

payload, end-users should talk to their trailer suppliers

83.5” is the newer wider track axle intended for use with

about the use of 83.5” axles with zero outset wheels.

wide singles and 0” outset wheels for increased track width,

A trailer specified with 83.5” inch axles is intended for

stability, and payload.

single tire use. Switching to dual tire configuration could

exceed the legal maximum overall width of 102”.

VEHICLE TRACK

End-users that have retrofitted vehicles with 2” outset

With a standard length axle and 2” outset wheels,

wheels should contact their respective vehicle, axle,

the resulting variation in track width is an increase of

or component manufacturers for specific application

approximately1.5”per side(3” total) as compared to

approvals or maintenance recommendations.

a dual tire configuration.

End-users that have retrofi

vehicles with 2” outset

Actual Track Width

wheels should contact their respective vehicle, axle,

or component manufacturers for specific application

approvals or maintenance recommendations.

Measurements are rounded.

Duals

Wheel

Outset

Inset

77.5"

Track Width

0" Outset

101.5"

X One Tires

Actual Track Width

80.5"

Track Width

2" Outset

Wheel

Outset

97.9"

Note: Measurements are nominal values

and could vary with manufacturer.

88 Section Five: MICHELIN^®X One^®Tires

BEARINGS

Wheel-end bearings for trucks and trailers are typically

TMCrecommendsall axle ends be checked annually or at

the tapered roller type with either grease, semi-fluid grease,

100,000 miles. For more information, refer to TMC RP631A,

or oil level lubrication. Anticipatedbearinglifeis compared

Recommendations for Wheel End Lubrication.

by running an ANSI (American National Standards Institute)

Usingstandardbearings witha 2” wheel outseton a N-type

L10a test to statistically determine the fatigue life. The test

spindle arrangement does reduce the L10a bearing life

variablesare wheel endloading(amountandlocation),

expectancy. Bearing manufacturers offer enhanced bearings

bearing end-play, tire and wheel weight, tire static loaded

for trailer and drive axle applications that provide L10a

radius, and duty cycle (vehicle speed and turn frequency

lifewith2”outset single wheels near thatof conventional

and lateral g loading). The output is L10a Weighted Bearing

bearings with dual wheels.

System Life in miles.

These bearings have an extra roller with a slightly

The common belief among fleet maintenance technicians

different contact geometry between the cup and cone and

is that bearings do not fail or wear out in normal service

are machined to tighter tolerances and a smoother surface

unless subjected to loss of lubricant, excessive endplay, or

finish.

excessive preload.

Timken’s 454-Series^™wheel bearings*:

However, due to increased variances in the quality

• One bearing for Dual and Wide Singles

of bearings in the market place, proper inspection/

- Specially designed to handle the 2” outset loads

maintenance practices should be employed to ensure

- Allows consistency within fleet

preventing premature failures and extending the life of the

- Provides flexibility of wheel arrangements

bearing.

• Compatible with industry standard components

- Use with popular axle and hub designs

Poor Quality Bearings

- Can retrofit onto existing equipment

• New bearings show pitting on the rollers

• Bearing failure mode is spalling across the entire roller

*For more information on the Timken^®454-Series^™wheel

• Bearing cage failures also occurs

bearings, visit The Timken Company at www.timken.com.

IMPORTANT: Somewheelbearingassemblieshave

warranties that may be voided when the wheel ends

are disassembled. Contact your axle and/or suspension

component supplier before removing any wheel end

components.

“New” Bearings

Old Bearings

Cone

Cup

MileMate^®Set*

Good Quality Bearings

• New bearings show a perfect clean finish

N Trailer Outer

NP454049

NP454011

Set 440

• Bearings fail in an expected failure mode; light spalling on

N Trailer Inner

NP454248

NP454210

Set 441

the loaded edge

R Drive Outer

NP454580

NP454572

Set 442

R Drive Inner

NP454594

NP454592

Set 443

P Trailer Inner & Outer

NP454445

NP454410

Set 444

*454-Series^™is a trademark of The Timken Company. Timken^®and MileMate^®are

the registered trademarks of The Timken Company.

See www.timken.com/454wheelbearing for Limited Warranty information.

New Bearings

Old Bearings

Section Five: MICHELIN^®X One^®Tires

ENGINE COMPUTERS / FUEL ECONOMY

Tire revolutions and axle ratio are inputs to the Engine

switching to MICHELIN^®X One^®tires, it is recommended that

Control Module (ECM) to manage road speed. Changing

SAE (Society of Automotive Engineers) J1321 (revision) -

from dual to MICHELIN^®X One^®tiresmay require changing

Type II Fuel Test be conducted to verify the values

the Tire Revolutions per Mile (Tire Revs./Mile) value in the

determined by the engine computer.

ECM in order to ensure speed, distance, and fuel economy

New EGR (Exhaust Gas Recirculation) engines may use

are accurate per indications. Reference the MICHELIN^®

diesel fuel to clean the DPF (Diesel Particulate Filter). When

Truck Tire Data Book (MWL40731) for proper Tire Revs./

checking fuel usage please be aware of the additional fuel

Mile values for the MICHELIN^®X One^®tires you chose.

used during regeneration of the DPF.

To accurately determine fuel efficiency gains from

AIR INFLATION AND PRESSURE MONITORING SYSTEMS

Proper inflation pressure is critical to the overall

recommended for that tire. A flat tire must be removed from

performanceofall tires on the road today.

the wheel, thoroughly examined, and properly repaired

Today’s radial truck tires will loseless than one psi per

prior to re-inflation and use.

month due to air migration through the casing. Faster loss

Some systems provide inflation pressure information

of inflation can only occur in conjunction with some sort

at the sensor site only, so the driver must walk around the

of leak in the wheel, valve stem, or tire structure. Whatever

vehicle to gather/view either the pressure reading or low

the source of the leak, it must be identified and corrected to

pressure warning. Other systems transmit the information

avoid further damage to that component, possibly leading

to the cab where it may be viewed by the driver, and/or sent

to a compromiseinsafety.

to a central facility if the vehicle is tracked by satellite.

AVAILABLE SYSTEMS

Tire Pressure Monitoring Systems (TPMS) have been

Automated Tire Inflation Systems (ATIS) are

not guarantees against low pressure situations.

legislated for all vehicles by the TREAD Act (Transportation

All vehicles should still be subject to pre-trip

Recall Enhancement, Accountability, and Documentation).

inspections, and systems operation should be

The implementation schedule is in place for vehicles with

verified routinely.

gross vehicle weight (GVW) below 10,000lbs, butis yet to be

determined for heavier vehicles. The existing systems

“read” the pressure in the tire via a sensormounted on the

Automated Tire Inflation Systems (ATIS)

valve stem, wheel, or inside the tire. Sensors that are not

are designed to addair tomaintain a preset pressure but do

physically inside the tire and wheel cavity cannot accurately

not havetheability to reduce the pressure should a tire be

measure the internal air temperature, so they are unable to

over inflated. These systems can account for slower leaks

determine the “cold inflation pressure.” In addition, external

(determined bytheair delivery capacity of the system)

sensors may require additional inflation line plumbing that

andprovidesomewarningto thedriverwhenthesystem

creates additional potential leak points.

is energized (adding air) or when it cannot keep up with

Monitoring systems may provide either pressure data or

the leak. Almost all inflation-only systems use air from the

alowpressure warning.Thepressuredatamaybe“hot”or

vehicle air brake system, so they will belimited inmax

“cold” pressure, so it is necessary that the person viewing

pressure and available volumetric flow. In addition, these

that data fully understands which pressure is reported

systems are usually only applied to trailer axles where

and what it means. Low pressure alarm systems only alert

plumbing the air supply line is easier.

the driver when the pressure in a particular tire (or pair of

Even with the inflation system in place, routine manual

dual tires if linked together) is below some fleet-chosen

inflation pressure checks are still required.

minimum. This value may be preset by the sensor supplier

Tire inflation systems may add air to tires determined to

or may be programmable by the fleet. Tire manufacturers,

bebelowsomefleet chosenpressure. SomeAutomatedTire

through the U.S. Tire Manufacturers Association (USTMA),

Inflation Systems (ATIS) will also allow pressure reduction

haveagreed that a tiremust be considered flat if the

onany tire on the vehicle tomaintain some given pressure

inflation pressure is 20% or more below the pressure

level. Such systems are rather expensive and more often

90 Section Five: MICHELIN^®X One^®Tires

used only on specialty vehicles (Military, emergency

AUTOMATED TIRE INFLATION SYSTEMS

response, National parks, etc.).

(ATIS) ON TRAILERS AND MISSED NAIL

Akeyfactor in anymonitoring orinflation system is

HOLES

determining whether the target or set pressure is a “hot”

Automated Tire Inflation Systems (ATIS) on trailers can

pressure or a “cold” one. This should be discussed with

sometimes make slow leaks caused by nails or other small

your tire manufacturer’s representative.

objects penetrating the crown area of the tire undetectable.

A slow leak can be compensated for by the air inflation

THE USE OF PRESSURE MONITORING

system. The warning light of the ATIS system will only

AND INFLATION SYSTEMS WITH MICHELIN^®

come on if the pressure in the tire drops below a certain

TRUCK TIRES

percent (usually 10%) of the regulated preset pressure. Even

whenthe pressure drops belowthis point, the light will go

In view of the increasing visibility and promotion for

off if the system is able to restore andmaintain the preset

the use of pressure monitoring and/or inflation systems,

pressure.

Michelin takes the following position:

The tires on trailers with ATIS systems should be visually

• Michelin has not and cannot test every system that

inspected before and after use and any imbedded objects

is being marketed/manufactured for effectiveness,

removed and the tire repaired. An undetected imbedded

performance, and durability.

object remaining in the tire can allow air infiltration and

• The use of these systems does not nullify the MICHELIN^®

consequently a possible catastrophic failure of the sidewall.

truck tire warranty unless it is determined that the

system somehow contributed to the failure or reduced

performance of the tire.

• Proper pressure maintenance is important for the optimal

performance of the tires, so it is important tomake sure

the system can maintain the pressures needed and/or can

detect accurately when the pressures are outside of the

normal operating range(s) for the loads being carried.

• It is the responsibility of the system manufacturer to

ensure that the tires are inflated as rapidly as possible

to the optimal operating pressure in order to prevent

internal damage to the tires.

• Michelin strongly urges the customer to put the

responsibility on the system’s manufacturer to prove and

support their claims.

In addition to the foregoing, please refer to the

MICHELIN^®Truck Tire Warranty Manual (MWE40021) for

a general discussion of what is and is not covered by the

warranty.

Section Five: MICHELIN^®X One^®Tires

TRUCK TYPE BY WEIGHT CLASS FOR USE WITH X ONE^®TIRES

CLASS 6

CLASS 7

CLASS 8

TRAILER

NOTES

19,501 to 26,000 lbs.

26,001 to 33,000 lbs.

33,001 lbs. and over

Weight: Not specified

GVW

Recommended

Applications

TOW

HOME FUEL

FUEL

DRY VAN

Contact

Michelin

FURNITURE

TRASH

DUMP

DOUBLES

For information

on the MICHELIN^®

XOne^®tire for the 4x2

STAKE

FIRE ENGINE

CEMENT

LIQUID TANK

application, refer to the

next page.

GVW - Gross Vehicle

COE VAN

SIGHTSEEING/COACH

REEFER

DRYBULK

Weight

The total weight of the

loaded vehicle includes

chassis, body, and

payload.

SINGLE AXLE VAN

TRANSIT BUS

TANDEM AXLE VAN

LOGGER

GCW - Gross

Combination Weight

Total weight of

loaded tractor-trailer

BOTTLER

INTERCITY BUS

PLATFORM

combination includes

tractor-trailer and

payloads.

GAWR - Gross Axle

LOW PROFILE COE

TANDEM REFUSE

SPREAD AXLE

Weight Rating

Maximum allowable

load weight for a

specific spindle, axle,

DROP FRAME

and wheel combination.

GCW TO 65,000

GCW TO 80,000

Identical vehicles may

appear in different

vehicle weight classes.

LOW PROFILE

DUMP

This is because of

HIGH PROFILE COE

TANDEM COE

a difference in the

components installed

in each vehicle such as

engines, transmissions,

REEFER

rear axles, and even

MEDIUM

HEAVY CONVENTIONAL

tires that are not readily

CONVENTIONAL

discernible in the

external appearance

of those particular

DEEP DROP

vehicles.

HEAVY TANDEM

CONVENTIONAL

AUTO TRANSPORTER

HEAVY TANDEM

CONVENTIONAL

SLEEPER

DOLLY

92 Section Five: MICHELIN^®X One^®Tires

RECOMMENDATION FOR USE OF MICHELIN^®X ONE^®TIRES IN 4x2 APPLICATIONS

4x2 Articulated Vehicles

Michelin still maintains that all types of motor vehicles

Handling studies have indicated that for certain

can be controlled in the event of a rapid tire pressure loss

types of commercial single axle (4x2) tractors pulling

under normal, legal driving conditions. Vehicle control

trailers, handlingmay be degradedin the event of a

in a rapid tire pressure loss situation is a matter of driver

rapid tire pressure loss when fitted with single tires.

education and training. To assist with this training,

Michelin recommends that single axle tractors fitted with

Michelin has produced a video entitled “Rapid Air Loss,

MICHELIN^®XOne^®tires on the driven axle always be

Truck-TheCritical Factor” toinstruct drivers on how to

equipped with an Electronic Stability Program (ESP).

handle a rapid tire pressure loss situation.

To view the video - “Rapid Air Loss, Truck - The Critical

Factor” - please visit our web page at www.michelintruck.

4x2 Straight Chassis Vehicles

com/reference-materials/videos/#/maintenance-and-

Testing has indicated that handling of 4x2 straight

training. For additional information, please contact your

chassis vehicles fitted with single tires on the drive axle

local Michelin sales representative, or contact Michelin

maybedegraded in the event of a rapid tire pressure loss,

using the website www.michelintruck.com.

especially when coupled with panic braking. Class 6 and 7

straight trucks fitted with MICHELIN^®X One^®tires should

also be equipped with anti-lock brake system (ABS) and/or

ESP. Such degradation in handling has been observed both

in curve, lane change, and straight line driving.

Section Five: MICHELIN^®X One^®Tires

TIRE PRESSURE MAINTENANCE PRACTICES

Below is tire pressure maintenance advice for users of the

on a vehicle carrying 17,480 lbs. per axle, the appropriate

MICHELIN^®X One^®wide single truck tires (445/50R22.5

pressure is 100 psi (cold).

LRL and 455/55R22.5 LRL).

For trailers equipped with a pressure monitoring

Proper pressure maintenance is critical to obtain

system, system pressure should be regulated based on

optimized performance from these tires. Due to the unique

the maximum load the axle will carry and be at the cold

casing design of theMICHELIN^® X One^® tire, traditional

equivalent for this load.

pressure adjustment practices for dual tires may not apply

When an aluminum wheel is used in the outset position,

to MICHELIN^®X One^®tires.

the new TR553E valve should be used. It is recommended

Cold inflation pressure should be based on maximum

that you verify air valve stem torque on all wheels put into

axle load in daily operation. Cold inflation pressures must

service. When installed, they should have correct torque,

not be lower than indicated in the tables below for actual

using the proper tool at 80 to 125 in./lbs.(7 to 11 ft./lbs.) for

axle loads. For additional information, please consult the

aluminum wheels and 35 to 55 in./lbs. (3 to 5 ft./lbs.) for steel

MICHELIN^®Truck Tire Data Book (MWL40731).

wheels. To checkfor slow leaks at the valve stem, use either a

For example, load range L (20 ply) tires like the

torque wrench byhand orspray asoapy solutionon the valve

445/50R22.5 MICHELIN^®X ONE^®LINE^™ENERGY D tires

to see if it is loose. To prevent galvanic corrosion on aluminum

haveamaximumpressureof120psi(cold) withaweight

wheels, lubricate the threads and o-ring of the valve stem with

carrying capacity of 20,400 lbs. per axle. If the tire is mounted

a non-waterbased lubricant before installation.

Wheel Diameter

PSI

100

105

110

115

120

125

130

MAXIMUM LOAD AND

PRESSURE ON SIDEWALL

22.5”

kPa

520

550

590

620

660

690

720

760

790

830

860

900

445/50R22.5 LRL

LBS SINGLE

13880

14620

15360

16060

16780

17480

18180

18740

19560

20400

10200 LBS at 120 PSI

X ONE LINE ENERGY D

X ONE LINE ENERGY T

X ONE MULTI ENERGY T

KGSINGLE

6300

6640

6960

7280

7620

7940

8240

8500

8860

9250

4625 KG at 830 kPa

X ONE XDN2

LBS SINGLE

15000

15800

16580

17360

18120

18880

19640

20400

21200

22000

11000 LBS at 120 PSI

455/55R22.5 LRL

X ONE XDN2

X ONE MULTI ENERGY T

KGSINGLE

6800

7160

7520

7880

8220

8560

8900

9250

9580

10000

5000 KG at 830 kPa

LBS SINGLE

16580

17360

18120

18880

19640

20400

21200

22000

22600

23400

11700 LBS at 130 PSI

455/55R22.5 LRM

X ONE XZU S

X ONE XZY3

KGSINGLE

7520

7880

8220

8560

8900

9250

9580

10000

10240

10600

5300 KG at 900 kPa

* Single configuration, or 2 tires per axle.

94 Section Five: MICHELIN^®X One^®Tires

COMPARATIVE MICHELIN^®X ONE^®TIRE

MICHELIN^®X ONE^®TIRE MOUNTING

SIZESWHEELS

INSTRUCTIONS

The MICHELIN^®X One^®tire must be mounted on

MICHELIN^®

MICHELIN^®X One^®

Dual

Dual Size

22.5 x 14.00” size wheels. Both steel and aluminum are

X One^®Tire Size

Tire Revs./Mile

available in Hub (Uni Mount) piloted, and currently

515

511

445/50R22.5

275/80R22.5

aluminum is available in Stud (Ball Seat) configuration.

(X One^®XDN^®2)

(XDN^®2)

Supplemental parts will be required with ‘Stud-Piloted’

492

11R22.5 or

495

wheels; i.e. front and rear outer cap nuts to replace inner

455/55R22.5

(X One^®XDN^®2)

275/80R24.5

(XDN^®2)

and outer nuts used for mounting traditional stud-piloted

dual assembly. Wheel specific questions should be directed

The MICHELIN^®X One^®tire requires the use of

to the wheel manufacturer. To ensure proper stud length,

22.5 x 14.00” wheels. Both steel and aluminum wheels

there should be 4 threads

Incorrect Lateral Clearance

are currently available in 0”, 0.56”, 1” and 2” outsets. The

visible from the nut. There

majority of the wheels currently offered have a 2” outset.

are nodifferencesinmount

Outset: The lateral distance from the wheel centerline to

or dismount procedures

the mounting surface of the disc. Outset places the wheel

other than when mounting

centerline outboard of the mounting (hub face) surface.

the MICHELIN^®X One^®tire

Inset places the wheel centerline inboard of the mounting

ontoavehicle, position the

(hub face) surface or over the axle. Thus a wheel with a 2”

tire so that the tire sits on

outset has the centerline of the wheel base 2” outboard from

the outbound side of the

the hub mounting surface.

wheel similar to where the

Some axle and hub manufacturers have recently clarified

outer dual would normally be

and confirmed their position concerning the use of such

positioned. Additionally, this

wheels with their respective components. While the position

will offer exceptional lateral

of the component manufacturers is not totally consistent,

clearance. Select a valve

the majority’s view concerning the retrofit of duals with

stem that can be accessed

MICHELIN^® XOne^® tirescan besummarizedas follows:

for pressure checks and is

Correct Lateral Clearance

installed facing outward.

Axle Type*

Spindle Type

Wheel Recommendation

Drive axles

“R”

0” to 2” outset wheels**

NOTE: Safety cages, portable and/or permanent, are also

Trailer axles

“P”

2” outset wheels

available and required forinflation of theMICHELIN^®

Check with component

X One^®tire assemblies.

Trailer axles

“N”

manufacturer.

* Many other axle and spindle combinations exist. Contact axle manufacturer.

** Contact axle manufacturer before retrofitting 2” outset wheels.

NOTE: Use of outset wheels may change Gross Axle

Weight Rating (GAWR). Consult vehicle and component

manufacturers.

Section Five: MICHELIN^®X One^®Tires

HEAT STUDY

BRAKE HEAT OVERVIEW

Excessive bead heat can affect tire life in many truck

Truck brake often reach very high temperatures. Brake

tire applications. Vehicles in urban and refuse service are

drums can reach temperatures of 600°F or more and are

most commonly associated with bead heat issues, but any

in very close proximity to the wheels. This heat can be

application that experiences hard braking can be affected.

easily transferred to the wheels and tires. Brake drum heat

Results of bead heat:

is transferred to the wheel primarily through radiation and

convection. The hot brake drum radiates heat in all directions

1. Immediate Failure: In some cases, after periods of

to the wheel. In addition, the drum heats the air between

hard braking where brake drums reach very high

temperatures (in excess of 600°F), immediate failure can

the drum and the wheel. The heated air rises and transfers

additional heat energy to the wheel through convection. Much

occur. This normally occurs when a truck is brought

of the heat is transferred to the wheel in the beadmounting

to a stop for a period of time with very high brake

area due to its close proximity to the brake drum. The wheel

temperatures. Often this occurs when an over-the-

then directly conducts heat to the tire bead resulting in

road truck stops at a truck stop at the bottom of a long

elevated temperatures in the tire bead area.

descent. As the heat rises from the brake drum, there

is excessive heat buildup in the portion of the tire bead

directly above the brake drum(inner beadof inside

dual). The high temperature can cause a breakdown

of the rubber products in the bead area and allow

the steel body cables to unwrap from the bead. This

process results in a tire rapid tire pressure loss. This

phenomenon is also common in urban and refuse fleets

when the driver stops for a break after a period of hard

braking.

2. Degradation of the carcass: Heat is a tire’s worst

enemy! A tire subjected to high heat conditions over

an extended period of time will experience accelerated

aging of the rubber products. The degradation may

result in a blowout during operation, oritmay render

the casing unsuitable for retread. The graph below

demonstrates how operating with bead temperatures in

excess of 200°F will significantly reduce your casing life.

Duals - Close to Brake Drum

CASING LIFE vs BEAD TEMPERATURE

400

350

300

250

200°F

200

150

1,000

10,000

100,000

1,000,000

10,000,000s

Casing Life (hr)

96 Section Five: MICHELIN^®X One^®Tires

Bead damage as a result of brake heat is recognizable

The third stage is when the casing ply fully unwraps

in 3 stages of severity. In the first stage, the bead starts

from the bead. In extreme cases, the casing ply unwraps

to turn inward. This can be visibly identified on the tire

from the bead all the way around the tire. At this point

when it is dismounted. A straight edge placed across the

the tire completely separates from the bead wire. The

beads from one bead to the other no longer rests on the

bead wire can entangle itself around the axle if this type of

beadpoint, but nowrestscloser to the bead bearingarea.

separation occurs.

3rd Stage - Partial Unwrapping of the Casing Ply

1st Stage - Turning of the Bead

The second stage occurs when the rubber in the bead

area starts to split or crack indicating that the steel casing

plies are starting to unwrap.

3rd Stage - Complete Unwrapping of the Casing Ply

2nd Stage - Bead Splitting from Heat

Section Five: MICHELIN^®X One^®Tires

BRAKE HEAT EVALUATION:

This effect was demonstrated on a closed course at the

Laurens Proving Grounds, Michelin’s 3,000 acre test facility.

MICHELIN^®X ONE^®TIRES VS DUALS

MICHELIN^®X One^®tire fitments have greater clearance

The Test

between the brakedrum andthe bead of the tire compared

A 4x2 straight truck outfitted with a temperature logging

to a dual assembly. In addition, due to the 2” outset of the

device was loaded to maximum legal limits and operated

wheel for the MICHELIN^®X One^®tires, more brake drum is

on a closed course with almost continuous starting and

exposed, which provides greater air flow around the drum.

stopping cycles. The truck was brought up to 30 mph and

These characteristics reduce the heat transfer from the

then stopped repeatedly for 45 minutes. The temperature

brakesto the tire and allow the brakes to run cooler.

logging device recorded brake drum and wheel

temperatures (in the bead area) every 10 seconds. The test

was run on both MICHELIN^®X One^®tires and duals at

similar track temperatures and weather conditions.

Exposed Brake Drum

After 45 minutes, when the brakes were at their peak temperature, the temperatures from the data loggers were compared.

The brake drums fitted with MICHELIN^®X One^®tires were over 100°F cooler and the wheels were over 30°F cooler in the

bead area than when equipped with Duals!

BRAKE TEMPERATURE

WHEEL TEMPERATURE

MICHELIN^®X ONE^®TIRES vs DUALS

220

700

200

600

180

500

160

400

140

300

120

200

100

Dual

Source: Recent evaluations at a Michelin facility in South Carolina.

MICHELIN^®X One^®Tire

98 Section Five: MICHELIN^®X One^®Tires

MOUNTING ON VEHICLE -

MICHELIN^®X ONE^®TIRE

DUALS

Mounting MICHELIN^®X One^®Tire on the Vehicle

Mounting Dual on the Vehicle

HUB PILOTED SINGLE

HUB PILOTED DUAL

1 assembly

2 assemblies

10 flange nuts (Either side)

STUD PILOTED SINGLE

STUD PILOTED DUAL

2 assemblies

4 assemblies

10 Cap nuts (Left side)

10 inner cap nuts (Left side)

10 Cap nuts (Right side)

10 inner cap nuts (Right side)

10 outer cap nuts (Left side)

10 outer cap nuts (Right side)

(22 Parts)

(44 Parts)

In addition, dual wheelsmust be clocked for valve

stem access through the hand holes.

Mounting on hub-centered axles for the MICHELIN^®X One^®tire or Dual should take ~ 2 minutes for each axle end.

While mounting Dual on axles with stud-centered hubs, additional time is required due to the installation of an inner

andouter nutfor eachstud andhaving toline uphand holes.

TORQUE

Once the tire and wheel assembly is mounted onto

the axle end using an air gun, the final torque of each

wheel nut must be applied using a calibrated torque

wrench to 450-500 foot-pounds. This is a safety

procedure that will help prevent loose and broken

components and potential wheel-offs.

Torque Wrench

Section Five: MICHELIN^®X One^®Tires

101

RETREAD AND REPAIR RECOMMENDATIONS

MICHELIN^®X ONE^®TIRE RETREAD AND

USING BUFFING TEMPLATES

REPAIR RECOMMENDATIONS

Check buff radius with the template after removing the

The MICHELIN^®X One^®tire may require some special

tire from the buffer. A 2mm gap is acceptable in the center

equipment to handle the wider tread and casing, it does not

of buffed surface when checking with the template.

require any special procedure to be repaired or retreaded.

NOTE: 1700 mm Buffing Template as available from

As with any tire, special care should be given to respect

TECH INTERNATIONAL (1-800-433-TECH/1-800-433-

the recommendations and guidelines associated with the

8342) See Pictures 1 and 2.

specific product to ensure optimum performance.

INITIAL INSPECTION

Inspect the MICHELIN^®X One^®casings as defined

Picture 1 - Buffing Template

by your retread process manufacturer or industry

recommended practices using appropriate equipment.

When using an electronic liner inspection device (such

as the Hawkinson NDT), a new wide base probe of at least

275 mm / 10.9 inches is required to insure sufficient and

consistent cable contact with the shoulder/upper sidewall

area. (Hawkinson part # PROBE ASSEMBLY 009).

It is recommended to slow the rotation speed or make

several additional cycles to catch as many small punctures

Picture 2 - Buffing Template

as possible.

Recommendedtread width ranges are given on Page

SHEAROGRAPHY

68 and may vary depending on the type and condition of

the MICHELIN^®X One^®casing. The MICHELIN^®X One^®

If using laser shearography inspection adjust and or

casing’s finished buffed measured width should follow the

modify to insure complete imaging shoulder to shoulder,

samestandards as other casings: treadwidth + 8 mm/-2mm.

per equipment manufacturer. Also make sure the correct

vacuum level is applied.

AFTER BUFF INSPECTION

If after buffing, circumferential cracks or splits remain

BUFFING

in one or both shoulders of the tire in the vicinity of the

An expandable rim width of 14.5 inches is required.

outside tread groove (Picture 3), the crack or split should

Buffi on a narrower rim can result in excess under-tread

be probed.If the probing penetrates into steel or feels soft/

on the shoulder, thereby increasing the operating belt edge

loose material, the casing should be rejected. This should

temperature. The beads of the casing should be lubricated

not be confused with a 360 degree product interface line that

with a fast drying tire lubricant. Runs of MICHELIN^®

sometimesisvisible after buff(Picture 4). If this line is visible,

X One^®tires should start with new blades which should

it should be probed and if found to be loose material, reject

be changed as soon as the buff texture starts to degrade.

the casing. If it is tight, continue the retread process.

Buffi should not start before the casing reaches target

pressure in the expandable rim as defi

by your retread

process manufacturer. Recommended minimum infl

pressure is 1.2 bars or 18 psi, maximum infl

pressure is

1.5 bars or 22 psi. Recommended buffi radius for pre-cure

fl treads (w/o wings) is 1700 mm ± 50 mm or 67 inches ± 2

inches.

Picture 3

Picture 4

102 Section Five: MICHELIN^®X One^®Tires

BUILDER

Principal Components

Expandable rim width of 14.5 inches is required.

Shoulder

Tread table rollers should be completely cleaned before

Crown

and/or after each build series. The base of the wider

MICHELIN^®X One^®tread will come in contact with the

roller’s outer edges, so care should be taken to prevent

contamination by cleaning the rollers at frequent intervals.

Tread building should not begin until tire pressure has

Crown Plies

reached the target inflation pressures in the expandable

Body Ply

rim as defined by your retread process manufacturer.

For cushion to casing extruded bonding gum

Inner Liner

application, recommended minimum inflation pressure

Sidewall

is 0.8 bar or 12 psi. Bonding gum thickness should not

exceed 1.5 mm (2/32 inch) in the crown and 2.5 mm (3/32

A’

inch) in the shoulders.

Note: For non-Michelin wing tread products, contact

75 mm

MRTDuncan, SC at 1-888-678-5470, then press 3 for

Technical Support.

75 mm

10 mm

Bead

ENVELOPING

Contact your envelope supplier for the recommended

size envelopes to be used.

Note: For truck sizes, point B is considered the “toe” of

the bead. Point A is found 75mm from point B towards

CURING

the interior of the casing, and point A’ is also 75 mm from

Cure the MICHELIN^®X One^®casing according to

point B but is located on the exterior of the casing. Point

cure law for the tread design per the retread process

C is located 10mm from point B (measured as shown).

manufacturer.

Any repair patch material must be positioned >10 mm

from the toe of the bead (point B).

FINAL INSPECTION

Perform a final inspection of the MICHELIN^®X One^®

Damage Guidelines

casing according to the retread process manufacturer

work method and specification.

Note: The retreader is still responsible for determining

if the MICHELIN^®X One^®casing is capable of being

retreaded; the same as would be done for any other tire in

the inspection process.

Sidewall Damage

Crown Damage

Bead Damage

Interior Damage

Section Five: MICHELIN^®X One^®Tires

103

REPAIR RECOMMENDATIONS

Type of Repair

Application

Quantity Limits

Size Limits

Long Haul, Pickup &

Max 10 per sidewall

No limit

Delivery (P&D)

Spot Repair

(no body ply affected)

Severe Service

Max 20 per sidewall

No limit

Max width: 150 mm (6 in)

All

Max 4 per bead

Min distance between repairs: 75 mm (3 in)

Bead Repairs

(rubber damage only)

Severe Service

L = 2 mm x W = 50 mm (1⁄16 in. x 2 in)

No limit

(bead toe repair only)

Min distance between repairs: 75 mm (3 in)

Bead Repairs

L = 25 mm x W = 55 mm (1 in. x 2 in)

All

Max 4 per bead

(chafer strip)

Min distance between repairs: 75 mm (3 in)

If blister diameter is less than 5 mm (3⁄16 in),

leave intact;

Repair between 5 mm (3⁄16 in) and 20 mm (3⁄4 in)

Liner Repairs

All

No limit

If blister diameter is more than 20 mm (3⁄4 in),

reject casing

Max diameter: 40 mm

(1.6 in)

Long Haul, P&D

Max 15 per tire

Buzzouts

Max surface: 1600 mm²(2.5 in²)

(protector ply of

3rd working ply)

Max diameter: 40 mm

(1.6 in)

Severe Service

Max 60 per tire

Max surface: 1600 mm²(2.5 in²)

Max diameter: 30 mm

(1.2 in)

Long Haul, P&D

Max 3 per tire

Buzzouts

Max surface: 900 mm²(1.4 in²)

(2nd working ply;

Infinicoil)

Max diameter: 30 mm

(1.2 in)

Severe Service

Max 20 per tire

Max surface: 900 mm²(1.4 in²)

Nail Hole Repairs

All

Max 5 per tire

Max diameter: 10 mm

(0.4 in)

Crown

Max diameter: 25 mm

(1.0 in)

Section Repairs

All

Max 2 per tire

Sidewall

L 70 mm x W 25 mm (2.8 in x 1.0 in)

L 90 mm x W 20 mm (3.8 in x 0.8 in)

L 120 mm x W 15 mm (4.7 in x 0.6 in)

For up to 6 mm nail hole repairs in the shoulder area, the repair unit should be upsized (larger than CT20) and offset to move the reinforcement

end as far away from the maximum flex area as possible.

RETREAD RECOMMENDATIONS

Tread Width

Casing Size

Buff Radius ⁽¹⁾

Circumference

Tread Type

Min

Max

1700 mm (± 50 mm)

3070 mm

Flat Tread

380 mm

390 mm

445/50R22.5

67 inches (± 2 inches)

121 inches

Wing Tread ⁽²⁾

375/420 mm

385/430 mm

1700 mm (± 50 mm)

3225 mm

Flat Tread

390 mm

400 mm

455/55R22.5

67 inches (± 2 inches)

127 inches

Wing Tread ⁽²⁾

385/430 mm

395/440 mm

1. For MRT Custom Mold™ Retread the buff radius should be 2200 mm (87 in).

2. For non-Michelin wing tread sizes contact MRT Technical Support at 1-888-678-5470, Option 3.

104 Section Five: MICHELIN^®X One^®Tires

CHAINS*

GEAR RATIO

Depending on the state in which you are traveling,

A change in tire dimension will result in a change in

chainsmay ormay not be required. If chains are

engine RPMat a set cruise speed** that will result in a

required, several companies have chains available for the

change in speed and fuel economy. The effect of tire size

MICHELIN^®X One^®tire. The thing to remember when

change on gear ratio should be considered in individual

purchasingchainsforyourMICHELIN^®X One^®tireis the

operations.

tire size, as the 445/50R22.5 chains don’t fi the 455/55R22.5

A decrease in tire radius will increase tractive torque and

and vice versa. For more information, consult your local

increase indicated top speed. An increase in tire radius will

dealer or go to www.tirechains.com.

reduce tractive torque and decrease indicated speed.

Tire Revs./Mile - Speed - Size: These factors can affect

engine RPM ifcorrespondingchangesarenotmade to

engine ratios.

Example: Going from larger diameter tire to smaller

diameter tire.

If you currently run a 275/80R22.5 MICHELIN^®XDN^®2

tire (511 Tire Revs./Mile) and change to a 445/50R22.5

MICHELIN^®X One^®XDN^®2 tire (515 Tire Revs./Mile),

the speedometer will indicate a slightly higher speed than

the actual speed the vehicle is traveling.

Final Tire Revs./Mile - Initial Tire Revs./Mile ₌

Initial Tire Revs./Mile

515 - 511 = 0.0078 or 0.78% (< 1% change)

511

So when your actual speed is 60 mph, your speedometer

will read 60.47 mph.

** Exceeding the legal speed limit is neither recommended nor endorsed.

MICHELIN^®X One^®Tire

MICHELIN^®X One^®Tire Size

Tire Revs./Mile

445/50R22.5

515 (X One XDN2)

Dual Size

Dual Tire Revs./Mile

275/80R22.5

511 (XDN2)

MICHELIN^®X One^®Tire

MICHELIN^®X One^®Tire Size

Tire Revs./Mile

* The information provided is for reference only.

Chain-specific questions should be directed to the chains

455/55R22.5

492 (X One XDN2)

manufacturer.

Dual Size

Dual Tire Revs./Mile

11R22.5 or 275/80R24.5

496 (XDN2)

Section Five: MICHELIN^®X One^®Tires

105

FOOTPRINT COMPARISONS TO DUAL TIRE FITMENTS

MICHELIN^®X ONE^®XDN^®2 TIRE - 445/50R22.5 versus MICHELIN^®XDN^®2 TIRE - 275/80R22.5

Take notice that switching to single tire fitments causes

support the loads your fleet encounters as defined in

a slight reduction in footprint area when compared

the MICHELIN^®Truck Tire Data Book (MWL40731).

to dual. This will not have a negative impact on your

Overinflation of the MICHELIN^®X One^®tires will

traction.

not only reduce the footprint but can adversely affect

The MICHELIN^®X One^®tire footprint will be dependent

handling, wear, and ride characteristics. Overinflating

on pressure recommendations and vehicle loads. One

tires may also result in exceeding the wheel’s maximum

should always select a pressure that will adequately

pressure.

445/50R22.5 MICHELIN^®X ONE^®XDN2^®AT 100 PSI

120 PSI FOOTPRINT OVERLAID ON 100 PSI FOOTPRINT

The photo below demonstrates what occurs to the footprint when you overinflate the same tire to

120 psi. The overinflated footprint’s length and width are reduced (black footprint) when compared

to 100 psi footprint (gray footprint).

Shoulder: -22 mm

Center: -12 mm

106 Section Five: MICHELIN^®X One^®Tires

OPERATION AND HANDLING

OVER-STEER

UNDER-STEER

Over-steer is when the rear wheels are carving a larger

Under-steer is when the front wheels are carving a

arc than the front wheels or the intended line of the turn.

larger arc than the rear wheels. This is often described

This is often described as a “loose” condition, as the truck

as “push” or “pushing,” as the front end feels like it is

feels like the rear end is coming around.

plowing off of a corner.

Over-steer: Very Difficult to Correct

Under-steer: Very Easy to Correct

Over-steer is dangerous because once the rear end comes around, the vehicle

is uncontrollable and may enter a spin. Braking only makes this condition worse.

Under-steer is the more desirable condition because you have direct control over

the front tires, and deceleration usually corrects the condition.

The MICHELIN^®X One^®tire has a higher cornering stiffness and can generate

more lateral force than standard dual drive tires. Increasing cornering stiffness of

the rear tires promotes under-steer. Additionally, it will take more force to jack-

knife the vehicle.

CORNERING STIFFNESS FOR DIFFERENT TIRES

7,000

6,000

5,000

4,000

3,000

2,000

MICHELIN X One Tire

1,000

Two Dual

Conventional Wide-Base

5,000

10,000 15,000 20,000 25,000

30,000 40,000 45,000 50,000

Normal Force (N)

Source: Recent evaluations at a Michelin facility in South Carolina.

Section Five: MICHELIN^®X One^®Tires

107

HYDROPLANING

A tire’s contact pressure can reduce your chance of

Hydroplaning occurs when the tire loses contact with

hydroplaning. The MICHELIN^®X One^®tire has higher

the road. This can happen when the water pressure

contact pressure at the edge of the tread, which provides a

exceeds the contact pressure between the tire and the

wider “sweet spot” than dual tires. In the graph below, you

road.

can see that the contact pressure is slightly higher in the

center and significantly higher at the shoulders over dual

fitments. Note the dropin contact pressure for dual tires on

the graph below.

For example, the contact pressure of a dual tire is about

90 psi compared to 116 psi for a MICHELIN^®X One^®tire.

This will result in the dual tire losing contact with the

road at lower speed than the MICHELIN^®X One^®tire.

This means if hydroplaning occurs at 60 mph for the

MICHELIN^®X One^®tire, it will occur at 53 mph on the

dual.

Contact Pressure Ratio = = (90/116) = 88% or

Factors that increase likelihood of hydroplaning:

60 mph x 0.88 = 53 mph

- Excess water

- Excessive speed

- Low tread depth

- High tire pressure

- Light loads or bob-tailing

In other words, if rain is pouring down and water is

pooling, the truck’s speedneeds to decreasein order to

avoid hydroplaning.

1,000

900

800

700

600

500

400

300

Dual Tire 1

200

MICHELIN^®X One^®Tire

100

Dual Tire 2

Rib Number

Source: Recent evaluations at a Michelin facility in South Carolina.

108 Section Five: MICHELIN^®X One^®Tires

ROLLOVER THRESHOLD

Duals

There are two things you canchange tomake

77.5"

a vehicle more resistant to rollover:

Track Width

- Lowerthe center of gravity

- Increase your track width

0" Outset

The MICHELIN^®X One^®tire does both.

First, the loaded radius of the 445/50R22.5

MICHELIN^® X One^® XDN^®2tire is 18.7”.

101.5"

A 275/80R22.5 MICHELIN^®XDN^®2 tire (dual

equivalent) loaded radius is 18.9”. See chart below.

X One Tires

For every inch you lower the Center of Gravity, you

gain 3 mph additional safety factor with regard to

80.5"

Track Width

rollover threshold.

Second, the track width is measured at the center

of where the load is distributed on the ground.

2" Outset

Fordual, this would bemeasured at the center of the

space between the dual. For the MICHELIN^®X One^®

tire, it is simply measured from the center of the left

97.9"

side tire to the center of the right side tire.

Asyoucansee,eventhoughtheoverallwidth

Note: Measurements are nominal values

and could vary with manufacturer.

has reduced, the track width has increased on the

MICHELIN^®X One^®tire.

ROLLOVER THRESHOLD WITH TIRE SIZE

In summary, the MICHELIN^®X One^®tire

0.42

improves rollover threshold by increasing

cornering stiffness, increasing track width, and

0.40

reducing the center of gravity.

0.38

These improvements have been validated with:

1) Computer simulation where the whole

0.36

vehicle is characterized mathematically.

2) Track testing at our internal proving grounds.

0.34

3) OE vehicle manufacturers in their independent

testing, including tilt table testing.

0.32

275/80R22.5 385/65R22.5 425/65R22.5 445/65R22.5

445/50R22.5

Source: Recent evaluations at a Michelin facility in South Carolina.

SPECIFICATIONS FOR TREAD DESIGN: MICHELIN^®X ONE^®XDN^®2

Tread

Max.

Max. Load and Pressure

Load

Catalog

Loaded Radius

Overall Diameter

Overall Width (‡)

Approved

Revs

Size

Depth

Speed (*)

Single

Range

Number

Wheel

Per Mile

32nds

mph

in.

lbs.

psi

kg.

kPa

445/50R22.5

36587

18.7

474

40.4

1026

17.1

435

14.00

515

10200

120

4625

830

SPECIFICATIONS FOR TREAD DESIGN: XDN^®2

Max.

Approved

Tread

Loaded

Overall

Overall Width

Min. Dual

Revs

Max. Load and Pressure

Load

Catalog

Speed

Wheels

Size

Depth

Radius

Diameter

(‡)

Spacing (‡) Per

Single

Dual

Range

Number

(*)

(Measuring wheel

32nds

mph

in.

listed first.)

Mile

lbs.

psi

kg.

kPa

lbs.

psi

kg.

kPa

275/80R22.5 ⁽¹⁾

63465

18.9

481

40.6

1030

11.0

279

8.25, 7.50

12.2

311

511

6175

110

2800

760

5675

110

2575

760

Section Five: MICHELIN^®X One^®Tires

109

JACK-KNIFE

When you put the tractor and trailer into an extreme

turn or “jack-knife” situation, the trailer is very vulnerable

to rollover.

Normally, traction has a positive influence on the

handlingof the truck. This is nolonger true when you put

a truck in a jack-knife condition. Whether dual or single

configuration, you are forcing the tires to stop rolling and

slide sideways. As the photo below clearly demonstrates,

the trailer is twisting because the tires are holding their

position on the road. This can lead to rollover!

This is especially true for spread axle trailers and high

center of gravity loads. Look at the lateral stress placed

on the tires from the jack-knife situation. Turning angles

should be minimized to avoid rollover threshold whether

operating with duals orMICHELIN^® XOne^® tires.

Turning angles should be minimized to avoid rollover

threshold whether operating with duals or MICHELIN^®

X One^®tires.

110 Section Five: MICHELIN^®X One^®Tires

NEVER exceed vehicle limitations because of improved

This can be simplified by remembering the following:

handling.

A tire with a wider footprint is going to provide

DROP

increased lateral stability when cornering. As a result

ROLL

of this increased lateral stability, the truck will have a

tendency to lean less in turns. The increased lateral

and STOP

stability should not equate to increased speed. Always

obey posted speed limits on the highways and curves.

In other words, the vehicle lean or DROP may be the

A good rule of thumb for vehicles with high rollover

first indication of a rapid tire pressureloss. Don’t jam on

thresholds (i.e., tankers, concrete mixers) is to take the

the brakes! Pumping the brakes will allow the damaged

curves at the posted limit less 10 mph.

wheel end to ROLL to a STOP without lock-up.

There are many MICHELIN^®X One^®tire training videos

RAPID TIRE PRESSURE LOSS PROCEDURE

including rapid tire pressure loss handling, and specific

Even though the MICHELIN^®X One^®tire is an

application demonstrations. To obtain one of these,

innovative product, it still requires proper pressure

contact your local Michelin dealer or the Michelin sales

maintenance and visual inspection practices. Tire failure

representative in your area.

can and will occur.

Below you will find a handy reference of the procedure

TRACTION

to bring the vehicle to a safe stop following a rapid tire

Traction is dependent on the following variables:

pressure loss event:

- speed

- tread depth

Indications:

- conditions (dry or wet, depth of water)

(Some or all of the following may apply.)

- tread design

- No change in handling

- tread rubber compound

- Slight lean (depending on wheel position)

- road surface (concrete, asphalt)

- Vibrations

- Audible noise when rapid tire pressure loss occurs

CHAINS*

Dependingonthestateinwhichyouaretraveling,

Immediate Actions:

chainsmay ormay not be required.If chainsare

- Accelerate enough to maintain lane position.

required, several companies have chains available for

(DO NOT apply brakes immediately.)

the MICHELIN^®X One^®tire. The thing to remember

- Do not apply maximum brake pressure to bring the

when purchasing chains for your MICHELIN^®X One^®

vehicle to a stop. This stop should be gradual by

tire is the tire size, as the 445/50R22.5 chains don’t fi the

pumping the brakes.

455/55R22.5 and vice versa. For more information, consult

- Creating assembly lock-up can cause irrepairable

your local dealer or go to www.tirechains.com.

damage to tire, wheel, axle components, and vehicle.

- Pull the vehicle to a safe area.

- Do not attempt to limp further down the road.

Secondary Actions:

- Turn on flashers

- Deploy safety triangles

- Inspect vehicle for damage

– Call for assistance

* The information provided is for

reference only. Chains-specific

questions should be directed to

the chains manufacturer.

Section Five: MICHELIN^®X One^®Tires

111

STOPPING DISTANCES

The following provides the top ten reasons not to limp home on

any tire.

Stoppingdistance with theMICHELIN^® XOne^®

tire is similar to that of a vehicle in dual

configuration. A general rule typically mentioned

TOP REASONS

in Commercial Driver’s License (CDL) manuals is

NOT TO LIMP HOME

to allow one vehicle length or one second between

your vehicle and the one you are following for every

10. Pavement Damage: when the tire is run to destruction,

the wheel contact damages the road.

10mph of your velocity. For example: if you are

9. Wheel Damage: $$$ hundreds of dollars.

driving at 65 mph, allow 6.5 seconds between your

8. Destroyed Casing: it may have otherwise been repairable.

vehicle and the one in front of you. A good way to

$$$ hundreds of dollars.

7. Cargo Damage: load shifts, collisions, roll-overs or fires.

practice this is to mark a spot, such as a bridge,

6. Collateral Truck Damage: fairings, tanks, hoses, brakes,

road sign, etc., that the vehicle you’re following

hoods, mudflaps, etc.

5. Wheel and/or Tire Detachment: if the tire/wheel become

has just passed and count one-one thousand, two-

detached, they become a projectile.

one thousand, etc., to see how long it takes you to

4. Adverse Handling Conditions: mishandled, a run-flat could

reach the same point. If you count to only four-one

lead to a jack-knife or even a roll-over.

3. Direct DOT Violation: fines/downtime/out-of-service.

thousand, then increase your following distance.

2. Creating assembly lock-up can cause irrepairable damage

In wet and/or icyconditions, do not assumethat

to tire, wheel, axle components, and vehicle.

because you have better traction you will be able to

1. Endangers Other Vehicles and People: heavy duty truck

accidents can be fatal.

stop quicker. It is always the best practice to increase

following distances and reduce driving speeds when

traveling in adverse weather conditions.

STATE AND LOCAL REGULATIONS

Some states have enacted “Load Per Inch Width” regulations for

LIMPING HOME

the purpose of governing axle weight on (primarily) the steering axle

Limping on the MICHELIN^®X One^®tire can cause

of commercial vehicles. These regulations provide a carrying capacity

damage to the wheel and casing. Although the tire

of a certain number of pounds per each cross-sectional inch across

is down, it’s possible that it is repairable unless it

the tire’s width. The determination of the tire’s width can vary from

was run-flat. Limping home is never recommended

state to state, but presumably would be based upon either the tire

evenondualtires. Limpingis a direct CSA

manufacturer’s published technical data for overall width, or the

(Comprehensive Safety Analysis) violation.

width asmarked on the sidewall of the tire (whichmay require

DOT (Department of Transportation) Regulation

conversion from Metric to English units). It is recommended to

393.75 states:

contact your state’s DOT office to confirm the current “Load Per Inch

Width” law.

Forexample, if a state allows for 550 pounds per inch width, a tire

marked 445/50R22.5 could carry up to 9,636 pounds (17.52 x 550) or

atotal of 19,272 pounds onthedrive axle(2 x 9636). Another way to

look at it is to take the total weight carried and divide by the stated

“Load Per Inch Width” law to determine the appropriate size tire.

If a truck needs to carry 16,000 pounds an axle in a state with a 500

pound per inch width limit (16000/500 = 32), you would need a

wide single tire that is at least 16 inches wide (32/2). In this case a

445/50R22.5 could legally carry the load (445 mm/25.4 mm per inch =

17.5 inches Metric to English conversion).

The two formulas are:

Load Per Inch Width Law x Tire Section Width x Number of Tires =

Gross Axle Weight Limit

Gross Axle Weight/Inch Width Law/Number Of Tires =

Minimum Tire Section Width Needed

State laws and regulations frequently can and do change, so it is

recommended that you consult your local State or Province DOT and

where you will be traveling to be sure there are no restrictions on

the use of the MICHELIN^®X One^®tire for your particular operation,

equipment, and weight.

112 Section Five: MICHELIN^®X One^®Tires

SECTION SIX

MICHELIN

^®RV Tires

Section Six

MICHELIN^®RV Tires

113-124

MAINTAINING RECREATIONAL VEHICLE TIRES

114-120

The Importance of Inflation Pressure

Inflation Pressure Requirements

When to Check Recreational Vehicle Tire Pressure

Tire Repairs

Tread Depth Measurements and Wear Bars

Dual Spacing

Directional Tires

Tire Pressure Monitoring Systems (TPMS)

Nitrogen

Workmanship and Materials

Location of Tire Identification Code

Service Life for Recreational Vehicle Tires

Selecting Alternative Tire Sizes

Drive at Proper Speeds

Long Term Storage

Aging, Weather Checking, and Ozone Cracking

Proper Cleaning of RV Tires

Tire Rotation, Balance, Alignment and Tire Wear

Common Tire Damages

HOW TO WEIGH THE RECREATIONAL VEHICLE

121-124

How to Weigh the RV

Three Different Types of Scales

Weighing the Single Axle Recreational Vehicle

Weighing the Tandem Axle Recreational Vehicle

The Effect of Towed Vehicles or Trailers

How to Use the Actual RV Weight Information

with the Tire Data Load Chart

Using Blocks to Level Motorhomes and RVs Equipped

with Radial Tires

For additional information about

MICHELIN^®RV Tires, refer to the

- business.michelinman.com

- MICHELIN^®Truck Tire Data Book - MWL40731

Section Six: MICHELIN^®RV Tires

113

MAINTAINING RECREATIONAL VEHICLE TIRES

The GCWR (Gross Combination Weight Rating) is the

THE IMPORTANCE OF INFLATION

value specified by the recreational vehicle manufacturer

PRESSURE

at themaximumallowableloadedweightwithatowed

Never drive on an overloaded

trailer or towed vehicle.

or underinflated tire.

These ratings can vary based on the different

components and vehicle options. To determine proper

The most critical factor in tire maintenance is proper

inflation pressure, Michelin recommends weighing each

inflation. Driving on any tire that does not have the

wheel position of the recreational vehicle individually.

correct inflation pressure is dangerous and will cause tire

Weighingeachaxleendindividually will give a clear

damage. Improper pressure for the weight of the vehicle

indication of how the weight of the recreational vehicle is

could cause premature wear, tire damage, or a harsher

distributed across the axle. If there is a difference in the

ride. The correct inflation pressure allows for full tread

weight found from one side to the other, adjust personal

contact with the road surface and promotes traction,

cargo within the vehicle in order to redistribute the load

braking capability, and handling.

more evenly across the axle.

An underinflated or overloaded tire will build up

For instructions on how to weigh a recreational vehicle,

more heat that could go beyond the endurance limits

see pages 121-124.

of the rubber, steel belts, and radial cords. This could

cause sudden tire failure. Underinflation will cause

poor handling, faster and/or irregular tire wear, and a

REMEMBER: For control of the recreational

vehicle, it is critical that the tire inflation

reduction in fuel economy. Overinflation, on the other

pressures are set to the same inflation pressure

hand, will reduce the tire’s contact area with the road

across an axle.

surface, which reduces traction, braking ability, and

handling. A tire that is overinflated for the weight it is

WHEN TO CHECK RECREATIONAL VEHICLE

carrying is more prone to a harsh ride, uneven tire wear,

TIRE PRESSURE

and impact damage.

For optimum performance and handling, it is important

to not only establish the proper inflation pressure, but

INFLATION PRESSURE REQUIREMENTS

it is also important to regularly inspect recreational

The amount of inflation

vehicle tires for cuts, snags, and penetrations. Failure to

pressure required in each tire

maintain correct inflation pressure may result in sudden

depends on the weight of the

tire destruction and/or improper vehicle handling.

fully loaded vehicle, to include

Additionally, it will result in irregular tire wear. Check

passengers, cargo load, fuel,

inflation pressures on all tires (including spares):

and water. To determine the

1. At a minimum, check weekly, and always before long

correct inflation pressure,

distance trips.

consider the various weight

2. On long trips, check every morning before driving.

ratings that are posted on the

3. Before and after storage, check and record tire

recreational vehicle chassis, or

pressures (a drop in pressure may indicate a slow

within the recreational vehicle

leak).

itself. The GVWR and the GAWR

The ideal time to check tire inflation pressures is early

stickers are normally located

morning. Driving, even for a short distance, causes tires

on the support pillar next to the

to generate heat, resulting in an increase in inflation

driver’s seat.

pressure. The stated pressures found in published load

The GVWR (Gross Vehicle Weight Rating) is the

inflation tables are based upon the cold tire inflation

maximum total weight rating for the recreational vehicle,

pressure at ambient outside temperature. A drop in

to include passengers, fluids, and cargo.

ambient temperature results in a drop in tire pressure;

The GAWR (Gross Axle Weight Rating) is the maximum

weight allowed across a single axle.

The UVW (Unloaded Vehicle weight) is the weight of

the recreational vehicle as built at the factory with full

Never exceed the maximum load or pressure

fuel, engine oil, and coolants. The UVW does not include

limits of the wheel. Exceeding the wheel limits

can lead to component failure, serious accident,

cargo, fresh water, LP gas, passengers or dealer installed

injury or death.

accessories.

114 Section Six: MICHELIN^®RV Tires

therefore, more frequent checks may be required during

TIRE REPAIRS

cold weather conditions. Avoid outdoor pressure checks

When a tire experiences a tread puncture, it may be

when the temperature is below freezing, as ice can form

safe to return it to service if it is properly repaired. A

in the valve stem and create aslow leak.

tiremust be repaired from theinside so that a careful

As a tire rotates during operation, it will naturally

inspection can be made to the inner liner. The tire

generate internal heat, resulting in an increase of inflation

technician should use a combination plug and patch,

pressure. The pressure foundina“hot” tiremay be as

where the rubber plug seals the damaged area from

much as 10 - 15 psi higher than the inflation pressure

outside contaminants and moisture, and the patch

found before operation. If checking tires after operation,

reinforces the inner liner. Consult a Michelin tire dealer

compare the inflation pressure of all tires to ensure that

for a professional inspection and repair.

they are within 2 - 3 pounds ofeachother across the axle.

Never bleed hot tires, or they

NEVER use a rope type string plug to repair a

will become underinflated.

MICHELIN^®tire. A rope plug is considered a

temporary repair and often leaks over time.

It is considered an improper repair and may void

Tire inflation pressures should be maintained across

the MICHELIN^®Truck Tire Limited Warranty.

an axle at the same inflation pressure, especially in dual

fitment. Make sure to check both tires in a dual fitment;

pressures should be the same. The maximum allowable

TREAD DEPTH MEASUREMENTS AND

difference between tires across an axle is 5 psi. Use a

WEAR BARS

quality, calibrated tire gauge to check inflation pressures,

Tires should be periodically measured for wear. This

preferably a truck tire pressure gauge with a dual angled

measurement should be taken in several spots across the

head. These gauges work best to check the inner and

tread, and around the circumference. If there is a variance

outer dual wheels. In addition, double seal valve caps and

in tread grooves greater than 2/32” across the face of

quality extension hoses simplify and expedite checking

the tire, consult a Michelin tire dealer for a professional

tire inflation pressures.

inspection.

For example, if the recommended tire pressure across

a rear dual axle is 80 psi, and one tire only has 64 psi, it is

considered to be flat. This tire, as well as the tire in service

next to it, should be removed from service by a tire

technician immediately. A qualified tire technician should

demountthetireto conduct athoroughtire andwheel

inspection before returning them to service.

MICHELIN^®tires contain “wear bars” in the tread

grooves of the tire tread, which show up when there is

only 2/32” remaining of tread rubber. When the tread is

wornlevel with the wear bar indicator, the tiremust be

removed from service. Federal law requires that, “any

tire on the front wheels of a bus, truck or truck tractor

shall have a tread groove pattern depth of at least 4/32

of an inch when measured at any point on a major tread

groove. The measurements shall not be made where tie

bars, humps or fillets are located”.

Underinflation in a dual configuration overloads the

properly inflated tire. Both tires must be inspected.

Section Six: MICHELIN^®RV Tires

115

Tires mounted in dual must be matched so that the

TIRE PRESSURE MONITORING SYSTEMS

maximum difference between the diameters of the tires

(TPMS)

does not exceed 1/4” diameter, or a circumferential

There are several manufacturers of Tire Pressure

difference of 3/4”. For tires of the same beaddiameter

Monitoring Systems (TPMS) available for recreational

and size, the maximum allowable difference in tread

vehicle usage. TPMS systems monitor internal tire

depth is 4/32”. When there is a difference in tread wear, fit

pressure levels during vehicle operation; some also

the least worn tire in the outside wheel position. Failure

provide the actual internal tire temperature readings.

to properlymatch dual tires will result in the tire with

Maintaining proper tire inflation will helpmaximize tire

the larger diameter carrying a disproportionate share of

life and fuel efficiency, and may result in a reduction

the load. Mismatched duals can lead to rapid tire wear,

inirregular tire wear and tire costs. If your recreational

uneven tread wear, and possible casing failure.

vehicle is fitted with a TPMS system, consult your Original

Equipment manufacturer or recreational vehicle dealer for

DUAL SPACING

specific service guidelines. While TPMS systems give an

Sufficient space must be maintained between dual tires

early warning of low inflation pressure, they should not be

to allow airflow and to prevent the tires from rubbing

considered as a replacement for manual tire inspections.

against one another. To make sure dual spacing is correct,

simplymeasure from the outside edge of theouter tire

NITROGEN

to the outside edge of the inner tire of the dual assembly,

The earth’s atmosphere is approximately 78% nitrogen,

and cross reference this measurement to the “minimum

along with 21% oxygen, and 1% other gases. Nitrogen is a

dual spacing” found on the tire data page. For additional

dry inert gas that does not retain moisture. While there are

assistance, consult a Michelin tire dealer.

advantages for aircraft and large off-the-road earthmover

tires to use 100% nitrogen systems, it is generally difficult

DIRECTIONAL TIRES

to quantify the advantages for over-the-road highway

operations. The predominant concern for proper tire

inflation is moisture in the compressed air system.

Moisture, when present in the tire, greatly accelerates

the oxidation effects to the tire and the wheel. Using well

maintained inflation equipment (compressor, inflation

lines, and in-line air dryer) will minimize the moisture

content of the compressed air in the tire. Increasing the

nitrogen percentage to 100% with a nitrogen inflation

systemwill not adversely affect the inner liner of the

tires, nor impact tire performance. Regular tire pressure

maintenance remains critical, and tire inflation check

intervals should not be extended due to nitrogen use.

MICHELIN^®X^®LINE^™ENERGY Z Steer Tire

WORKMANSHIP AND MATERIALS

MICHELIN^®truck tires bearing the Michelin name

Several MICHELIN^®tires feature directional tread

and complete serial or identification numbers, used

designs to increase tread life and to reduce irregular wear.

in consumer service such as on a recreational vehicle,

Directional tires have arrows molded into the shoulder/

are covered by a limited warranty against defects in

edge of the outer tread rib to indicate the intended

workmanship and materials for the life of the original

direction of rotation. To maximize tire performance,

tread or five years from the date of purchase, whichever

directional tires should be mounted correctly on wheels to

occurs first. At that time, all warranties, expressed or

ensure that the directionality is respected when mounted

implied, expire. Please visit www.michelinrvtires.com

on the recreational vehicle.

under “Reference Materials” for complete details about

Once directional tires are worn greater than 50% of the

the MICHELIN^®Truck Tire Warranty, and to complete the

original tread depth, there is generally no negative effect

MICHELIN^®Tire Registration. For tires that were fitted

of running them in adirection opposite to the indicated

new on an Original Equipment vehicles (i.e. acquired by

direction of rotation.

the consumer on a new recreational vehicle), for warranty

Operating new directional tires in the opposite direction

purposes, the purchase date of the brand new recreational

of that indicated on the tire will result in a premature

vehicle serves as the date of tire purchase.

onset of irregular wear, an increase in tire noise levels, and

a significant reduction in tread life.

116 Section Six: MICHELIN^®RV Tires

LOCATION OF TIRE IDENTIFICATION CODE

SELECTING ALTERNATIVE TIRE SIZES

The Department of Transportation (DOT) requires

Original Equipment manufacturers carefully select the

that all tires produced for U.S. highways have a Tire

proper tire and wheel for optimum performance and

Identification Number (TIN) imprinted on the tire. This

handling. When replacing tires on a recreational vehicle,

unique identifier is referred to as the DOT code and is

follow theinformation foundon the vehicle placard.

found on the lower sidewall of the tire. The DOT code

Michelin recommends maintaining the original tire size

begins with the letters “DOT”; the last four digits indicate

recommended on the placard, as changing to a different

the week and the year of manufacture. In the example

size may impact the overall vehicle performance. Consult

below, the DOT code ending with “0316” indicates a tire

your recreational vehicle dealer or a Michelin tire dealer

madeinthe3rdweek(Jan)of2016.

before changing tire sizes.

OPTIONAL CODE

MANUFACTURE

DATE

DRIVE AT PROPER SPEEDS

TIRE SIZE

MICHELIN

PLANT

DOT

Do not drive at speeds faster than the speed

ratings for your tires. Never exceed legal speed

limits or speeds reasonable for the driving

conditions.

High speed driving can be dangerous and may damage

your tires. The maximum continuous speed at which

MICHELIN^® tires canbe operated is indicatedin the

following data pages. Exceeding this maximum speed will

SERVICE LIFE FOR RECREATIONAL

cause the tire to build up excessive heat that can result in

VEHICLE TIRES

sudden tire destruction, property damage, and personal

MICHELIN^®tires are designed to meet the highest

injury. When driving at highway speeds, correct inflation

criteria for quality, performance, and durability. In

pressure is especially important. Michelin does not

addition to natural rubber, MICHELIN^®tires contain

endorse exceeding legal speed limits.

more than 200 different raw materials to provide superior

strength and flexibility throughout the life of the tire. Over

LONG TERM STORAGE

time, these components naturally evolve; the evolution

When a tire is fitted to a wheel and put under load,

depends upon many factors such as the environment,

but it is not regularly used, the tire does not have an

storage conditions, and conditions of use (load, speed,

opportunity to “exercise” and will prematurely age.

inflation pressure, and maintenance). Therefore, it is

If a recreational vehicle is not driven regularly, care

impossible to predict when tires should be replaced based

mustbetakentopreservetheremaininglife of the tires.

on their calendar age alone.

Best practices include:

Some recreational vehicle owners may choose to oper-

1. Store the recreational vehicle in a cool, dry,

ate MICHELIN® tires after the tire warranty expires. For

sealed garage, away from electric generators or

consumers who choose to operate tires beyond the tire’s

warranted life, Michelin recommends frequent tire inspec-

transformers. Do not store in an area where welding

tions, especially before long trips. Michelin recommends

is performed, or in a garage that has frequently used

that anytires that are 10 years ormore from the date of

electric motors.

manufacture, including spare tires, be replaced with new

2. Place a barrier between the tire and the storage

tires as a precaution even if such tires appear serviceable

surface. Suitable barriers include plastic, plywood,

and even if they have not reached the legal wear limit.

cardboard, or rubber floor mats.

In addition to frequent tire inspections and proper

3. Before storing the vehicles, thoroughly clean tires

inflation pressure maintenance, Michelin recommends

with soap and water.

regular tire inspections by trained tire technicians.

4. If outdoors, cover tires to block direct sunlight and

Consumers are strongly encouraged to be aware not only

ultraviolet rays.

of their tire visual conditions and inflation pressures,

5. Inflate tires to the maximum inflation pressure

but also of any changes in dynamic performances which

indicated on the sidewall.

could be an indication that the tires need to be removed

6. If long term storage exceeds 3 months, consider

from service. Indications include an increased level of

taking the recreational vehicle for monthly highway

noise or vibration, or an increased frequency in loss

drives(about one hour of operational time). Driving

of inflation pressure (faster than 2 psi per month). For

the vehicle will give the tires an opportunity to

additional assistance, consult a Michelin tire dealer.

generate internal heat which will promote long life.

Section Six: MICHELIN^®RV Tires

117

Before removing the vehicle from long term storage,

TIRE ROTATION, BALANCE, ALIGNMENT

thoroughly inspect each tire, and restore all tires to the

AND TIRE WEAR

proper inflation pressure.

When tires are properly mounted and maintained

with the correct inflation pressure, they should wear in

AGING, WEATHER CHECKING, AND

a smooth even wear pattern. To maximize tire wear,

OZONE CRACKING

Michelin recommends the following best practices.

During tire inspections, check the sidewalls for signs of

1. Tire Rotation. MICHELIN^®tires should be rotated

aging, referred to as weather checking or ozone cracking.

when necessary. If the tires are wearing evenly, there

Aging appears as tiny cracks in the rubber surface of the

is no need to rotate. If tires begin to show an irregular

sidewall. If the cracks are less than 2/32” deep, the tire is

wear pattern, or if the wear rate on the tires from axle

acceptable to keep in operation; when the cracks extend

to axle or side to side is perceptively different, the tires

deeper than 2/32”, the tire should be inspected by a

should be rotated. There is no restriction on criss-

Michelin tire dealer and possibly replaced.

cross rotation; however, if the vehicle is equipped

with a spare tire/wheel is should be included into

Topromote long life and prevent prematuretire aging:

the rotation pattern. If using directional tires, and

1. Keep tires properly inflated and rotated.

if the tires are less than 50% worn, ensure tires are

2. Keep tires clean, avoiding petroleum products,

mountedto rotate in the proper direction. Once a

alcohol, and silicone.

directional tire has worn more than 50% of its tread, it

is acceptable to rotate into any position.

Considerations about tire rotations include:

• The load carried by a particular tire in a particular

wheelposition varies. Theinside tirein a dual

position carries more load than the outside tire on

the same axle.

• Curbing damage and weather checking often

occurs on the outside sidewall of the outside tire.

• Tires in dual should not differ more than 1/4”

diameter (4/32” tread wear). When there is a

4. Avoid prolonged exposure to high heat, extreme

difference in tread wear, fit the least worn tire in

cold, and ultraviolet rays.

the outside wheel position.

5. Cover the tires when the vehicle is not in use.

• When there is irregular wear, rotate the tires so

6. Follow the recommendations for long term storage

they turn in the opposite direction.

(Page 117).

2. Tire Balance and Runout. Check with

your recreational vehicle dealer for tire balance

PROPER CLEANING OF RV TIRES

recommendations. It is customary to check tire and

Proper cleaning of tires is important to obtain the

wheel assembly balance and runout if there is a ride

maximum years of service. Road oil will cause deterioration

complaint.

of rubber, and dirt buildup will hold contaminants next to

If there is a ride disturbance, validate that tire

the tire. A soft brush and mild car wash soap is the best way

inflation pressures are properly adjusted. If inflation

to clean tires.

pressures are correct, consult your recreational vehicle

If a dressing product is used on a sidewall, use extra

dealer or a Michelin tire dealer for assistance.

care and caution. Tire dressings that contain petroleum

In order to identify the source of the ride

products, alcohol, or silicones may cause premature aging

disturbance, consider the following factors to assist the

and sidewall cracking.

servicing dealer:

In many cases, it is not the dressing product itself that

• Road conditions when the vibration occurs.

can be a problem, but rather, the chemical reaction that

• Vehicle speed and engine rpms when the vibration

the product can have with the antioxidant waxes found

occurs.

in the tire. Heat can add to this negative reaction. When

• Where the vibration seems to be coming from

these same dressing products are applied to a passenger

(front or rear of the vehicle).

car tire that is replaced every three or four years, itis rare

• Frequency of the vibration (Does it phase in/out,

to see a problem. However, since Recreational Vehicle

or is it constant?).

tires usually last much longer, there is more time for a

chemical reaction to occur.

118 Section Six: MICHELIN^®RV Tires

3. Alignment. The purpose of alignment is to

Camber Wear. Also known as edge wear, camber

minimize tire wear and to maximize predictable

wear appears on the inside or outside shoulders of the

vehicle handling and driver control. Toe misalignment

tread. Wear on the inside edge of both tires may be due

is the number one cause of steer tire irregular wear.

to negative camber or toe-out misalignment. If only one

In order to optimize tire wear, consider the following:

tire shows edge wear, check for worn kingpin bushings,

• Tires that are not operated at a normal

bent or worn steering components, or excessive positive

(perpendicular) angle to the road surface typically

camber. For solid beam axles, excessive camber can result

produce uneven tire wear. Tires that are aimed

from axle over-load.

in contrasting directions (because of conflicting

alignment angles) produce unfavorable and

irregular tire wear.

• Tires that are used on highly compliant

suspensions will likely produce irregular tire wear.

• Alignments should be conducted in the

most representative loading condition of the

recreational vehicle, to include cargo load, fuel,

and water.

• Check with your recreational vehicle dealer for

Camber Wear

specific alignment specifications.

Toe Wear. A feathered wear pattern on the front

tires typically indicates misalignment (toe-in or toe-out).

Sometimes, a radial tire will not have this wear pattern

unless the toe condition is severe. Instead of the feathered

edge wear, the tire will be worn on the inside or outside

shoulder, which could be confused with camber wear.

On a three axle recreational vehicle, a skewed rear axle

and/or tag axle could cause feathered edge wear on one

shoulder of one front tire, and feather edge wear on

Camber Wear

the opposite shoulder of the other front tire. In order to

correctly diagnose a tire wear condition, the recreational

COMMON TIRE DAMAGES

vehicle should have an all-wheel alignment.

No tire is indestructible. Certain conditions of use and

abuse can stress a tire beyond its operating limits, causing

it to be prematurely removed from service. Below are 4

tire damages observed on recreational vehicles. This list is

not all inclusive; for additional information, consult your

Michelin tire dealer.

1. Underinflation. Underinflation is often referred

to as a “run-flat” tire and is caused by operating a

Toe Wear

tire at very low or zero pressure. A tire is considered

to be flat when it has operated at less than 80% of

the recommended inflation pressure. When a tire is

underinflated for the load it is carrying, the sidewall

flexes too much and it builds up heat. The tire is

unable to effectively dissipate the heat, and the

heat damages the inner liner, the casing, and the

outer sidewall of the tire. When a tire is operated

underinflated, the tire casing is irreversibly damaged.

If a tire has been operated underinflated, there

Toe Wear

will be physical signs of damage. The inner liner will

show signs of marbling or creasing. The sidewall may

show signs of creasing or flexing damage. In some

cases, if an extremely underinflated tire is operated at

highway speeds, the tire may unseat itself and it will be

Section Six: MICHELIN^®RV Tires

119

destroyed as the wheel rolls on the uninflated sidewall.

When one tire in a dual configuration comes out of

service due to underinflation, the other tire in the dual

Re-inflation of any type of tire and wheel

configuration should be inspected immediately. If the

assembly that has been operated in a run-flat

or underinflated condition (80% or less of

unserviceable tire was underinflated, the serviceable

recommended operating pressure) can result

dual tire was carrying more of the load for that wheel

in serious injury or death. The tire may be

position. As a result, the properly inflated tire may

damaged on the inside and can explode during

have suffered casing damage. When performing tire

inflation. The wheel may be worn, damaged, or

service on MICHELIN^®truck tires with steel casings,

dislodged and can explosively separate.

follow industry safety guidelines. Always use tire safety

cages during the inflation process.

3. Dual Kissing. Dual Kissing damage occurs when

two tires in dual configuration make contact with

each other while in operation. The heat generated by

the friction between the two tires severely weakens

the casing material of both tires. The condition may

be caused by incorrect wheel width, incorrect wheel

offset, or underinflation.

EFFECT: Inner Liner Marbling - Creasing

CAUSE: Underinflation

2. Fatigue Rupture. Fatigue Rupture damage is

sometimes called a “zipper” because of the zipper-

like effect it creates in the steel casing cords of the

EFFECT: Friction Severely Weakens the Casing

damaged tire. When casing cables are repeatedly

CAUSE: Dual Kissing

bent due to overload and/or underinflation, they are

damaged and will eventually break. Since all of the tire

4. Dynamometer Damage. Dynamometer type

cables are exposed to the same amount of stress, many

damageoccursinthecrownareaoftireswhen

will rupture at the same time. This severe rupture is

operated on dynamometers for extended periods of

extremely dangerous and can happen unexpectedly:

time. If a service provider does not adhere to

hours, days or even months after the initial overload

recommended guidelines pertaining to the maximum

happened. Whenever performing tire service on

time and permitted speed for dynamometer testing,

MICHELIN^®truck tires with steel casings, follow

irreversible tire damage may later appear on the tread

industry safety guidelines. Always use tire safety cages

surface. For additional information about the

during the inflation process.

maximum time and permitted speeds, consult your

Michelin tire dealer.

Fatigue Rupture or “Zipper”

EFFECT:

Any Damage

That Will Allow

the Casing to

EFFECT:

Oxidize

Internal Deterioration

of the Tread Rubber

CAUSE:

Moisture

CAUSE:

Prolonged Use of

Dynamometer

120 Section Six: MICHELIN^®RV Tires

HOW TO WEIGH THE RECREATIONAL VEHICLE

NOTE: Michelin recommends using a professional weighing group or organization to perform the weighing of your Motorhome/

RV. The Recreational Vehicle Safety Foundation (RVSEF) is an organization that performs weighing and other educational

services. They can be contacted at www.rvsafety.com. If you are planning to do your own weighing, you should follow the

procedures below. Michelin recommends checking with the scale operator to make sure there are no concerns on damage to the

scale or to the vehicle if weighing side to side to determine individual wheel position weights.

HOW TO WEIGH THE RV

First, the RV must be weighed fully loaded - that includes passengers, food, clothing, fuel, water, propane, supplies, and

anything else you can think of. Also, any towed vehicle (car, boat, or trailer) or item loaded on brackets on the back of the RV (like

bikes or motorcycles) should be included in the weighing.

THREE DIFFERENT TYPES OF SCALES:

Platform - Platform scales are usually long enough to weigh the entire vehicle at once.

Michelin suggests the following:

a) Pull onto the scale so that only the front axle is on the platform. The rear end of the scale

needstobemidwaybetweenthefrontandrearaxles.Recordtheweight.

b) Pull forward until the full unit is on the scale. Record the weight.

c) Pull forward until only the rear axle is on the platform. The front end of the scale needs to

be midway between the front and rear axles. Record the weight.

SCALE

d) If the RV has a rear tag axle, pull forward so only tag axle is on the scale. Record the weight.

e) To determine individual wheel position weights, repeat steps (a) through (d) with only one

side of the vehicle actually on the scale and the vehicle centered over the side of the scale.

See diagram on next page. Record the weights.

f) Tocalculate the opposite wheel positions’ weights, subtract the weights recordedin step

(e) from the weights recorded in steps (a) through (d). If there is not a towed vehicle, the tag

axle weight derived from (d) will represent the actual weight on the tag axle.

g) If a vehicle is being towed, it should be weighed and combined with the GVW (Gross

Vehicle Weight) to ensure the total weight doesn’t exceed the GCWR (Gross Combined

Weight Rating).

Segmented Platform - Platform scales with segmented sections can provide individual axle

weights and total vehicle weights all at once when the vehicle is positioned properly.

To do this, simply:

a) Position the vehicle on the scales so that each axleis centered asmuch as possible on the

segments, and record the weight.

b) Reposition the vehicle so that only one side is on the scale - centered on the segment as

much as possible.

SCALE

c) Subtract the weighed wheel positions from the total axle weights to determine the

unweighed wheel position weights.

Single Axle - Weighs one axle at a time.

Follow these steps:

a) Drive the front axle onto the scale and stop long enough for the weight to be recorded.

b) Pull vehicle forward until the rear axle is on the scale.

c) For gross vehicle weight, add the two axle weights together.

d) To obtain the individual wheel position weights, repeat this process with only one side of

the RVonthescale.

SCALE

Note: Even though the weight of the total axle is within the axle rating, it may be overloaded

on one side, whichmeans anoverloaded wheel position. That’s why side-to-side weighing is

required.

Section Six: MICHELIN^®RV Tires

121

The RV must remain as level as possible on the scale (even when an axle or side isn’t on the scale). Therefore, to

obtain side-to-side weights, there must be enough space on either side of the scale to accommodate the RV being

partially off the scale.

If there is a difference in the weights on one side of the vehicle as compared to the other, it is important to

redistribute the load more evenly to avoid component failure and improve handling. These weights make it possible

to compare against the GAWR (Gross Axle Weight Rating), GVWR (Gross Vehicle Weight Rating), and tire capacities.

They also help determine proper tire pressure.

WEIGHING THE SINGLE AXLE RECREATIONAL VEHICLE

TO OBTAIN INDIVIDUAL AXLE AND GROSS VEHICLE WEIGHTS

STEP 1a

STEP 1b

STEP 1c

STEP 1d

Scale Weight

lbs.

(Step 1a =

(Step 1b =

(Step 1c =

(Step 1d)

Gross Axle Weight)

Gross Vehicle Weight)

Gross Axle Weight)

From

lbs.

Owner’s

Gross Axle

Gross Vehicle

Gross Axle

Vehicle Weight

Manual

Weight Rating

(Gross Combined

Weight Rating -

Gross Vehicle Weight)

TO OBTAIN INDIVIDUAL WHEEL POSITION WEIGHTS

STEP 2a

STEP 2b

STEP 2c

One Side

Scale Weight

lbs.

(Step 2a)

(Step 2b)

(Step 2c)

Calculate Other

lbs.

Side Weight

(Step 1a-2a)

(Step 1b-2b)

(Step 1c-2c)

lbs.

Tire Load (lbs.)

(See Note #1)

(See Notes #1 & #2)

Inflation

psi

(See Note #1)

NOTES:

1. From the tire manufacturer’s load and infl

tables or the sidewall of the tires mounted on the vehicle.

2. If vehicle has duals, read dual capacity from tire and multiply by 2 to obtain dual assembly load capacity.

122 Section Six: MICHELIN^®RV Tires

WEIGHING THE TANDEM AXLE RECREATIONAL VEHICLE

TO OBTAIN INDIVIDUAL AXLE AND GROSS VEHICLE WEIGHTS

STEP 1a

STEP 1b

STEP 1c

STEP 1d

STEP 1e

(calculated)

lbs.

Scale

(Step 1a =

(Step 1b =

(Step 1c)

(Step 1d =

Drive Axle

Weight

Gross Axle Weight)

Gross Vehicle Weight)

Gross Axle Weight)

Weight = (1c-1d)

lbs.

From

Gross Axle

Gross Vehicle

Gross Axle

Owner’s

Manual

Weight Rating

TO OBTAIN INDIVIDUAL WHEEL POSITION WEIGHTS

STEP 2a

STEP 2b

STEP 2c

STEP 2d

(calculated)

One Side

lbs.

Scale Weight

(Step 2a)

(Step 2b)

(Step 2c)

Step 2d: Right Duals = (2b-2c)

lbs.

Calculate Other

Side Weight

(Step 1a-2a)

(Step 1c-2b)

(Step 1d-2c)

Left Duals = (2d)

lbs.

Tire Load (lbs.)

(See Note #1)

(See Notes #1 & #2)

psi

Inflation

(See Note #1)

NOTES:

1. From the tire manufacturer’s load and infl

tables or the sidewall of the tires mounted on the vehicle.

2. If vehicle has duals, read dual capacity from tire and multiply by 2 to obtain dual assembly load capacity.

THE EFFECT OF TOWED VEHICLES OR TRAILERS

Ifyour RV is towing a vehicle, you need to know the RV’s GCWR (GrossCombinedWeight Rating),the total actual loaded

weight of the RV, plus the total actual loaded weight of the towed vehicle. Even though the GCWR hasmore to do with the

design limits of the drivetrain (engine, transmission, axle, brakes, and bearings), the additional weight can also affect the tires

and the RV’s handling. Also, always remember to consider the tongue weight of the trailer and its effect on handling.

Section Six: MICHELIN^®RV Tires

123

HOW TO USE THE ACTUAL RV WEIGHT

USING BLOCKS TO LEVEL MOTORHOMES

INFORMATION WITH THE TIRE DATA

AND RVS EQUIPPED WITH RADIAL TIRES

LOAD CHART

Let’s consider an RV running on 275/80R22.5

MICHELIN^®X^®LINE ENERGY Z LRG tires, with actual

Assure that tires are properly supported during

corner weights of 5,400 lbs. on the left front tire, 5,175 lbs.

storage to avoid structural damage to the tire.

on the right front tire, 8,500 lbs. on the left rear duals, and

9,200 lbs. on the right rear duals. For control of the RV, it is

When using blocks to level motorhomes or RVs,

critical that the tire pressures be the same across an axle.

extreme caution must be taken to make sure the tires

Therefore, wemust “overinflate” the right front tire and

are fully supported. The weight on the tire should be

the left rear duals. Checking the load/inflation table below

evenly distributed on the block. And in the case of duals,

shows that a cold tire pressure of 95 psi will support 5,510

it should be evenly distributed on blocks for both tires.

lbs. on a single front tire.

Ifnot, the sidewall cables can become fatigued and

To determine the pressure for the rear duals, again take

damaged, resulting in a sidewall rupture and a complete,

the heaviest position, in this instance the right rear weighs

sudden loss of pressure.

9,200 lbs. The load/inflation table below shows that a cold

Note in the correctmethod, the blocks are wider

pressure of 85 psi will support 9,380 lbs. on 2 dual tires. It

than the tread and longer than the tire’s footprint. This

is important to note that the cold inflation pressure for the

provides maximum support to the tires and assures that

tire must never exceed the maximum inflation rating that is

the load is evenly distributed.

stamped on the wheel.

CORRECT - Evenly supporting the full load.

REMEMBER: For control of the recreational

vehicle, it is critical that the tire inflation

pressures are set to the same inflation pressure

across an axle.

Tofind the proper inflation pressure, refer to the

load and inflation charts in the MICHELIN^®RV Tires

(MWL43146) or visit www.michelinrvtires.com. These

charts have been altered for RV usage only.

S = 1 tire on 1 side of single axle

Single Axle

INCORRECT - One tire or only a portion of

one tire is supporting the full load.

D = 2 tires on 1 side of dual axle

Dual Axle

For Tag axle, use applicable

Single or Dual chart

LOAD AND INFLATION TABLE

This chart is for RV wheel end use only.

275/80R22.5 LRG - MICHELIN^®X^®LINE ENERGY Z

PSI

100

105

110

kPa

480

520

550

590

620

660

690

720

760

4500

4725

4940

5155

5370

5510

5780

5980

6175

LBS

8190

8600

9080

9380

9770

10140

10520

10880

11350

2040

2140

2240

2340

2440

2500

2620

2710

2800

3720

3900

4120

4260

4440

4600

4780

4940

5150

MAXIMUM LOAD AND PRESSURE

ON SIDEWALL

6175 LBS at 110 PSI

5675 LBS at 110 PSI

2800 KG at 760 kPa

2575 KG at 760 kPa

124 Section Six: MICHELIN^®RV Tires

MICHELIN TRUCK TIRE. SERVICE MANUAL (2017) - page 2