10-44 Vehicle Care
Tire Sidewall Labeling
Useful information about a tire
is molded into its sidewall.
The examples below show a
typical passenger vehicle tire
and a compact spare tire
sidewall.
Passenger (P‐Metric) Tire Example
(A) Tire Size:The tire size is
a combination of letters and
numbers used to define a
particular tire's width, height,
aspect ratio, construction type,
and service description. See the
“Tire Size” illustration later in
this section for more detail.
(B) TPC Spec (Tire
Performance Criteria
Specification)
:Original
equipment tires designed to
GM's specific tire performance
criteria have a TPC specification
code molded onto the sidewall.
GM's TPC specifications meet
or exceed all federal safety
guidelines.
(C) DOT (Department of
Transportation)
:The
Department of Transportation
(DOT) code indicates that the
tire is in compliance with the U.S. Department of
Transportation Motor Vehicle
Safety Standards.
(D) Tire Identification
Number (TIN)
:The letters and
numbers following the DOT
(Department of Transportation)
code is the Tire Identification
Number (TIN). The TIN shows
the manufacturer and plant
code, tire size, and date the tire
was manufactured. The TIN is
molded onto both sides of the
tire, although only one side may
have the date of manufacture.
(E) Tire Ply Material
:The type
of cord and number of plies in
the sidewall and under the tread.
(F) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required to
grade tires based on three
performance factors: treadwear,
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10-46 Vehicle Care
(F) Tire Size:A combination of
letters and numbers define a
tire's width, height, aspect ratio,
construction type, and service
description. The letter T as the
first character in the tire size
means the tire is for temporary
use only.
(G) TPC Spec (Tire
Performance Criteria
Specification)
:Original
equipment tires designed to
GM's specific tire performance
criteria have a TPC specification
code molded onto the sidewall.
GM's TPC specifications meet
or exceed all federal safety
guidelines.
Tire Designations
Tire Size
The following illustration shows
an example of a typical
passenger vehicle tire size.
(A) Passenger (P‐Metric) Tire:
The United States version of
a metric tire sizing system.
The letter P as the first
character in the tire size
means a passenger vehicle
tire engineered to standards
set by the U.S. Tire and Rim
Association.
(B) Tire Width
:The three‐digit
number indicates the tire section
width in millimeters from
sidewall to sidewall. (C) Aspect Ratio
:A two‐digit
number that indicates the tire
height‐to‐width measurements.
For example, if the tire size
aspect ratio is 60, as shown in
item C of the illustration, it would
mean that the tire's sidewall is
60 percent as high as it is wide.
(D) Construction Code
:
A letter code is used to indicate
the type of ply construction in
the tire. The letter R means
radial ply construction; the
letter D means diagonal or bias
ply construction; and the letter B
means belted‐bias ply
construction.
(E) Rim Diameter
:Diameter of
the wheel in inches.
(F) Service Description
:These
characters represent the load
index and speed rating of the
tire. The load index represents
the load carry capacity a tire is
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Vehicle Care 10-49
Radial Ply Tire:A pneumatic
tire in which the ply cords that
extend to the beads are laid at
90 degrees to the centerline of
the tread.
Rim
:A metal support for a tire
and upon which the tire beads
are seated.
Sidewall
:The portion of a tire
between the tread and the bead.
Speed Rating
:An
alphanumeric code assigned to
a tire indicating the maximum
speed at which a tire can
operate.
Traction
:The friction between
the tire and the road surface.
The amount of grip provided.
Tread
:The portion of a tire
that comes into contact with
the road. Treadwear Indicators
:Narrow
bands, sometimes called wear
bars, that show across the
tread of a tire when only 1.6 mm
(1/16 inch) of tread remains.
See When It Is Time for New
Tires
on page 10‑58.
UTQGS (Uniform Tire Quality
Grading Standards)
:A tire
information system that
provides consumers with
ratings for a tire's traction,
temperature, and treadwear.
Ratings are determined by
tire manufacturers using
government testing procedures.
The ratings are molded into
the sidewall of the tire. See
Uniform Tire Quality Grading
on
page 10‑62
. Vehicle Capacity Weight
:
The number of designated
seating positions multiplied by
68 kg (150 lbs) plus the rated
cargo load. See
Vehicle Load
Limits
on page 9‑22.
Vehicle Maximum Load on the
Tire
:Load on an individual tire
due to curb weight, accessory
weight, occupant weight, and
cargo weight.
Vehicle Placard
:A label
permanently attached to a
vehicle showing the vehicle's
capacity weight and the original
equipment tire size and
recommended inflation pressure.
See “Tire and Loading
Information Label” underVehicle
Load Limits
on page 9‑22.
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10-50 Vehicle Care
Tire Pressure
Tires need the correct amount
of air pressure to operate
effectively.
Notice:Do not let anyone tell
you that under‐inflation or
over‐inflation is all right. It is
not. If your tires do not have
enough air (under‐inflation),
you can get the following:
.Too much flexing
.Too much heat
.Tire overloading
.Premature or
irregular wear
.Poor handling
.Reduced fuel economy If your tires have too much air
(over‐inflation), you can get
the following:
.Unusual wear
.Poor handling
.Rough ride
.Needless damage from
road hazards
A vehicle specific Tire and
Loading Information label is
attached to your vehicle.
This label shows your vehicle's
original equipment tires and the
correct inflation pressures for
your tires when they are cold. The recommended cold tire
inflation pressure, shown on the
label, is the minimum amount of
air pressure needed to support
your vehicle's maximum load
carrying capacity.
For additional information
regarding how much weight
your vehicle can carry, and an
example of the Tire and Loading
Information label, see
Vehicle
Load Limits
on page 9‑22.
How you load your vehicle
affects vehicle handling and ride
comfort. Never load your vehicle
with more weight than it was
designed to carry.
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Vehicle Care 10-51
When to Check
Check your tires once a month
or more. Do not forget to
check the compact spare tire,
if the vehicle has one. The
compact spare should be at
60 psi (420 kPa). For additional
information regarding the
compact spare tire, see
Compact Spare Tire
on
page 10‑73
.
How to Check
Use a good quality pocket-type
gage to check tire pressure.
You cannot tell if your tires are
properly inflated simply by
looking at them. Radial tires
may look properly inflated even
when they are under‐inflated. Check the tire's inflation
pressure when the tires are
cold. Cold means your vehicle
has been sitting for at least
three hours or driven no more
than 1.6 km (1 mile).
Remove the valve cap from the
tire valve stem. Press the tire
gage firmly onto the valve to get
a pressure measurement. If the
cold tire inflation pressure
matches the recommended
pressure on the Tire and
Loading Information label, no
further adjustment is necessary.
If the inflation pressure is low,
add air until you reach the
recommended amount.
If you overfill the tire, release air
by pushing on the metal stem
in the center of the tire valve.
Re‐check the tire pressure with
the tire gage.
Be sure to put the valve caps
back on the valve stems.
They help prevent leaks by
keeping out dirt and moisture.
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10-52 Vehicle Care
Tire Pressure for
High-Speed Operation
{WARNING
Driving at high speeds, 160 km/h
(100 mph) or higher, puts an
additional strain on tires.
Sustained high-speed driving
causes excessive heat build up
and can cause sudden tire failure.
You could have a crash and you
or others could be killed. Some
high-speed rated tires require
inflation pressure adjustment for
high speed operation. When
speed limits and road conditions
are such that a vehicle can be
driven at high speeds, make sure
the tires are rated for high speed
operation, in excellent condition,
and set to the correct cold tire
inflation pressure for the
vehicle load.If your vehicle has P235/55R18 size
tires, they will require inflation
pressure adjustment when driving
your vehicle at speeds of
160 km/h (100 mph) or higher.
Set the cold inflation pressure
to the maximum inflation pressure
shown on the tire sidewall,
or 262 kPa (38 psi), whichever is
lower. See the example following.
When you end this high-speed
driving, return the tires to the cold
tire inflation pressure shown on the
Tire and Loading Information label.
See
Vehicle Load Limits
on
page 9‑22and Tire Pressureon
page 10‑50.
Example:
You will find the maximum load and
inflation pressure molded on the
tire's sidewall, in small letters,
near the rim flange. It will read
something like this: Maximum load
690 kg (1521 lbs) 300 kPa (44 psi)
Max. Press. For this example, you would set the
inflation pressure for high‐speed
driving at 262 kPa (38 psi).
Tire Pressure Monitor
System
The Tire Pressure Monitor System
(TPMS) uses radio and sensor
technology to check tire pressure
levels. The TPMS sensors monitor
the air pressure in your vehicle's
tires and transmit tire pressure
readings to a receiver located in the
vehicle.
Each tire, including the spare
(if provided), should be checked
monthly when cold and inflated to
the inflation pressure recommended
by the vehicle manufacturer on the
vehicle placard or tire inflation
pressure label. (If your vehicle has
tires of a different size than the size
indicated on the vehicle placard or
tire inflation pressure label, you
should determine the proper tire
inflation pressure for those tires.)
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Vehicle Care 10-53
As an added safety feature, your
vehicle has been equipped with a
tire pressure monitoring system
(TPMS) that illuminates a low tire
pressure telltale when one or
more of your tires is significantly
under‐inflated.
Accordingly, when the low tire
pressure telltale illuminates, you
should stop and check your tires as
soon as possible, and inflate them
to the proper pressure. Driving on a
significantly under‐inflated tire
causes the tire to overheat and can
lead to tire failure. Under‐inflation
also reduces fuel efficiency and tire
tread life, and may affect the
vehicle's handling and stopping
ability.
Please note that the TPMS is
not a substitute for proper tire
maintenance, and it is the driver's
responsibility to maintain correct tire
pressure, even if under‐inflation has
not reached the level to trigger
illumination of the TPMS low tire
pressure telltale.Your vehicle has also been
equipped with a TPMS malfunction
indicator to indicate when the
system is not operating properly.
The TPMS malfunction indicator is
combined with the low tire pressure
telltale. When the system detects a
malfunction, the telltale will flash for
approximately one minute and then
remain continuously illuminated.
This sequence will continue upon
subsequent vehicle start‐ups as
long as the malfunction exists.
When the malfunction indicator is
illuminated, the system may not be
able to detect or signal low tire
pressure as intended. TPMS
malfunctions may occur for a variety
of reasons, including the installation
of replacement or alternate tires or
wheels on the vehicle that prevent
the TPMS from functioning properly.
Always check the TPMS malfunction
telltale after replacing one or more
tires or wheels on your vehicle to
ensure that the replacement or
alternate tires and wheels allow the
TPMS to continue to function
properly.
See
Tire Pressure Monitor
Operation
on page 10‑54for
additional information.
Federal Communications
Commission (FCC) and
Industry and Science Canada
See Radio Frequency Statementon
page 13‑16for information
regarding Part 15 of the Federal
Communications Commission (FCC)
Rules and RSS-210/211 of Industry
and Science Canada.
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10-54 Vehicle Care
Tire Pressure Monitor
Operation
This vehicle may have a Tire
Pressure Monitor System (TPMS).
The TPMS is designed to warn the
driver when a low tire pressure
condition exists. TPMS sensors are
mounted onto each tire and wheel
assembly, excluding the spare tire
and wheel assembly. The TPMS
sensors monitor the air pressure in
the vehicle's tires and transmit the
tire pressure readings to a receiver
located in the vehicle.
When a low tire pressure condition
is detected, the TPMS illuminates
the low tire pressure warning light
on the instrument panel cluster.The low tire pressure warning light
comes on at each ignition cycle until
the tires are inflated to the correct
inflation pressure.
The low tire pressure warning light
may come on in cool weather when
the vehicle is first started, and then
turn off as you start to drive. This
may be an early indicator that the
air pressure in the tire(s) are getting
low and need to be inflated to the
proper pressure.
A Tire and Loading Information
label, attached to your vehicle,
shows the size of your vehicle's
original equipment tires and the
correct inflation pressure for your
vehicle's tires when they are cold.
See
Vehicle Load Limits
on
page 9‑22, for an example of the
Tire and Loading Information label
and its location on your vehicle.
Also see Tire Pressure
on
page 10‑50.
Your vehicle's TPMS system can
warn you about a low tire pressure
condition but it does not replace
normal tire maintenance. See Tire
Inspection
on page 10‑57, Tire
Rotationon page 10‑57and Tireson
page 10‑43.
Notice: Liquid tire sealants could
damage the Tire Pressure Monitor
System (TPMS) sensors. Sensor
damage caused by using a tire
sealant is not covered by your
warranty. Do not use liquid tire
sealants.
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