Ford GT (2018 year). Manual - part 47

G. H: Indicates the tire's speed
rating. The speed rating denotes
the speed at which a tire is
designed to be driven for extended
periods of time under a standard
condition of load and inflation
pressure. The tires on your vehicle
may operate at different
conditions for load and inflation
pressure. These speed ratings may
need to be adjusted for the
difference in conditions. The
ratings range from 81 mph
(130 km/h) to 186 mph
(299 km/h). These ratings are
listed in the following chart.

Note: You may not find this
information on all tires because it
is not required by federal law.

Speed rating

Letter
rating

81 mph (130 km/h)

M

87 mph (140 km/h)

N

93 mph (150 km/h)

P

99 mph (160 km/h)

Q

106 mph (170 km/h)

R

112 mph (180 km/h)

S

118 mph (190 km/h)

T

124 mph (200 km/h)

U

130 mph (210 km/h)

H

149 mph (240 km/h)

V

168 mph (270 km/h)

W

Speed rating

Letter
rating

186 mph (300 km/h)

Y

>186 mph

(300 km/h)

ZR

Note: For tires with a maximum
speed capability over 149 mph
(240 km/h), tire manufacturers
sometimes use the letters ZR. For
those with a maximum speed
capability over 186 mph (299
km/h), tire manufacturers always
use the letters ZR.

H. U.S. DOT Tire Identification
Number (TIN): This begins with
the letters DOT and indicates that
the tire meets all federal
standards. The next two numbers
or letters are the plant code
designating where it was
manufactured, the next two are
the tire size code and the last four
numbers represent the week and
year the tire was built. For
example, the numbers 317 mean
the 31st week of 1997. After 2000
the numbers go to four digits. For
example, 2501 means the 25th
week of 2001. The numbers in
between are identification codes
used for traceability. This
information is used to contact
customers if a tire defect requires
a recall.

I. M+S or M/S: Mud and Snow, or
AT: All Terrain, or

AS: All Season.

J. Tire Ply Composition and
Material Used: Indicates the
number of plies or the number of
layers of rubber-coated fabric in
the tire tread and sidewall. Tire
manufacturers also must indicate
the ply materials in the tire and the
sidewall, which include steel,
nylon, polyester, and others.

K. Maximum Load: Indicates the
maximum load in kilograms and
pounds that can be carried by the
tire. See the Safety Compliance
Certification Label (affixed to
either the door hinge pillar,
door-latch post, or the door edge
that meets the door-latch post,
next to the driver's seating
position), for the correct tire
pressure for your vehicle.

L. Treadwear, Traction and
Temperature Grades:

*Treadwear The treadwear grade
is a comparative rating based on
the wear rate of the tire when
tested under controlled conditions
on a specified government test
course. For example, a tire graded
150 would wear one and one-half
times as well on the government
course as a tire graded 100.

*Traction: The traction grades,
from highest to lowest are AA, A,
B, and C. The grades represent the
tire's ability to stop on wet
pavement as measured under
controlled conditions on specified
government test surfaces of
asphalt and concrete. A tire
marked C may have poor traction
performance.

*Temperature: The temperature
grades are A (the highest), B and
C, representing the tire's
resistance to the generation of
heat and its ability to dissipate
heat when tested under controlled
conditions on a specified indoor
laboratory test wheel.

M. Maximum Inflation
Pressure: Indicates the tire
manufacturers' maximum
permissible pressure or the
pressure at which the maximum
load can be carried by the tire. This
pressure is normally higher than
the vehicle manufacturer's
recommended cold inflation
pressure which can be found on
the Safety Compliance
Certification Label (affixed to
either the door hinge pillar,
door-latch post, or the door edge
that meets the door-latch post,
next to the driver's seating
position), or Tire Label which is
located on the B-Pillar or the edge
of the driver’s door. The cold
inflation pressure should never be
set lower than the recommended
pressure on the vehicle label.

The tire suppliers may have
additional markings, notes or
warnings such as standard load
or radial tubeless.

Location of the Tire Label

You will find a Tire Label
containing tire inflation pressure
by tire size and other important
information located on the driver’s
side door opening.

Inflating Your Tires

Safe operation of your vehicle
requires that your tires are
properly inflated. Remember that
a tire can lose up to half of its air
pressure without appearing flat.

Every day before you drive, check
your tires. If one looks lower than
the others, use a tire gauge to
check pressure of all tires and
adjust if required.

At least once a month and before
long trips, inspect each tire and
check the tire pressure with a tire
gauge (including spare, if
equipped). Inflate all tires to the
inflation pressure recommended
by Ford Motor Company.

You are strongly urged to buy a
reliable tire pressure gauge, as
automatic service station gauges
may be inaccurate. Ford
recommends the use of a digital
or dial-type tire pressure gauge
rather than a stick-type tire
pressure gauge.

Use the recommended cold
inflation pressure for optimum tire
performance and wear.
Under-inflation or over-inflation
may cause uneven treadwear
patterns.

WARNING

Under-inflation is the most
common cause of tire failures

and may result in severe tire
cracking, tread separation or
blowout, with unexpected loss of
vehicle control and increased risk
of injury. Under-inflation increases
sidewall flexing and rolling
resistance, resulting in heat
buildup and internal damage to
the tire. It also may result in
unnecessary tire stress, irregular
wear, loss of vehicle control and
accidents. A tire can lose up to
half of its air pressure and not
appear to be flat!

Always inflate your tires to the
Ford recommended inflation
pressure even if it is less than the
maximum inflation pressure
information found on the tire. The
Ford recommended tire inflation
pressure is found on the Safety
Compliance Certification Label
(affixed to either the door hinge
pillar, door-latch post, or the door
edge that meets the door-latch
post, next to the driver's seating
position), or Tire Label which is
located on the B-Pillar or the edge

of the driver’s door. Failure to
follow the tire pressure
recommendations can cause
uneven treadwear patterns and
adversely affect the way your
vehicle handles.

Maximum Inflation Pressure is
the tire manufacturer's maximum
permissible pressure and the
pressure at which the maximum
load can be carried by the tire. This
pressure is normally higher than
the manufacturer’s recommended
cold inflation pressure which can
be found on the Safety
Compliance Certification Label
(affixed to either the door hinge
pillar, door-latch post, or the door
edge that meets the door-latch
post, next to the driver's seating
position), or Tire Label which is
located on the B-Pillar or the edge
of the driver’s door. The cold
inflation pressure should never be
set lower than the recommended
pressure on the Safety
Compliance Certification Label or
Tire Label.

When weather temperature
changes occur, tire inflation
pressures also change. A 43°F

(6°C) temperature drop can
cause a corresponding drop of
1 psi (7 kPa) in inflation pressure.
Check your tire pressures
frequently and adjust them to the
proper pressure which can be
found on the Safety Compliance
Certification Label or Tire Label.

To check the pressure in your
tire(s):

1. Make sure the tires are cool,

meaning they are not hot from
driving even a mile.

Note: If you are checking tire
pressure when the tire is hot, (for
example, driven more than 1 mi
(1.6 km)), never bleed or reduce air
pressure. The tires are hot from
driving and it is normal for
pressures to increase above
recommended cold pressures. A
hot tire at or below recommended
cold inflation pressure could be
significantly under-inflated.

Note: If you have to drive a
distance to get air for your tire(s),
check and record the tire pressure
first and add the appropriate air
pressure when you get to the
pump. It is normal for tires to heat
up and the air pressure inside to go
up as you drive.

2. Remove the cap from the valve

on one tire, then firmly press
the tire gauge onto the valve
and measure the pressure.

3. Add enough air to reach the

recommended air pressure.

Note: If you overfill the tire, release
air by pressing on the metal stem
in the center of the valve. Then
recheck the pressure with your tire
gauge.

4. Replace the valve cap.
5. Repeat this procedure for each

tire, including the spare.