
Q:What is wrong with this?
A:The belt is twisted across the body.
{CAUTION:
You can be seriously injured by a twisted belt.
In a crash, you would not have the full width
of the belt to spread impact forces. If a belt
is twisted, make it straight so it can work
properly, or ask your dealer to x it.
1-25

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.
(A) Tire Size:The tire size is a combination of letters
and numbers used to de ne 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
Speci cation):Original equipment tires designed
to GM’s speci c tire performance criteria have a
TPC speci cation code molded onto the sidewall.
GM’s TPC speci cations 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 Identi cation Number (TIN):The letters and
numbers following DOT (Department of Transportation)
code is the Tire Identi cation 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, traction,
and temperature resistance. For more information
seeUniform Tire Quality Grading on page 5-66.
(G) Maximum Cold In ation Load Limit:Maximum
load that can be carried and the maximum pressure
needed to support that load. Passenger (P-Metric) Tire Example
5-56

(A) Temporary Use Only:The compact spare tire or
temporary use tire has a tread life of approximately
3,000 miles (5 000 km) and should not be driven
at speeds over 65 mph (105 km/h). The compact spare
tire is for emergency use when a regular road tire
has lost air and gone at. If your vehicle has a compact
spare tire, seeCompact Spare Tire on page 5-88
andIf a Tire Goes Flat on page 5-71.
(B) Tire Ply Material:The type of cord and number
of plies in the sidewall and under the tread.(C) Tire Identi cation Number (TIN):The letters
and numbers following the DOT (Department of
Transportation) code is the Tire Identi cation 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.
(D) Maximum Cold In ation Load Limit:Maximum
load that can be carried and the maximum pressure
needed to support that load.
(E) Tire In ation:The temporary use tire or compact
spare tire should be in ated to 60 psi (420 kPa).
For more information on tire pressure and in ation
seeIn ation - Tire Pressure on page 5-61.
(F) Tire Size:A combination of letters and numbers
de ne a tire’s width, height, aspect ratio, construction
type, and service description. The letter T as the
rst character in the tire size means the tire is for
temporary use only.
(G) TPC Spec (Tire Performance Criteria
Speci cation):Original equipment tires designed
to GM’s speci c tire performance criteria have a TPC
speci cation code molded onto the sidewall. GM’s
TPC speci cations meet or exceed all federal safety
guidelines. Compact Spare Tire Example
5-57

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
rst 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 range and speed rating of the tire. The load
index represents the load carry capacity a tire is certi ed
to carry. The load index can range from 1 to 279. The
speed rating is the maximum speed a tire is certi ed
to carry a load. Speed ratings range from A to Z.
Tire Terminology and De nitions
Air Pressure:The amount of air inside the tire pressing
outward on each square inch of the tire. Air pressure
is expressed in pounds per square inch (psi) or
kilopascal (kPa).
Accessory Weight:This means the combined weight
of optional accessories. Some examples of optional
accessories are, automatic transmission, power steering,
power brakes, power windows, power seats, and air
conditioning.
Aspect Ratio:The relationship of a tire’s height to
its width.
5-58

Different Size Tires and Wheels
If you add wheels or tires that are a different size than
your original equipment wheels and tires, this may affect
the way your vehicle performs, including its braking, ride
and handling characteristics, stability, and resistance
to rollover. Additionally, if your vehicle has electronic
systems such as, anti-lock brakes, traction control, and
electronic stability control, the performance of these
systems can be affected.
{CAUTION:
If you add different sized wheels, your vehicle
may not provide an acceptable level of
performance and safety if tires not
recommended for those wheels are selected.
You may increase the chance that you will
crash and suffer serious injury. Only use GM
speci c wheel and tire systems developed for
your vehicle, and have them properly installed
by a GM certi ed technician.
SeeBuying New Tires on page 5-64andAccessories
and Modi cations on page 5-3for additional information.
Uniform Tire Quality Grading
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
section width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration (NHTSA), which grades tires
by treadwear, traction, and temperature performance.
This applies only to vehicles sold in the United States.
The grades are molded on the sidewalls of most
passenger car tires. The Uniform Tire Quality Grading
(UTQG) system does not apply to deep tread, winter-type
snow tires, space-saver, or temporary use spare tires,
tires with nominal rim diameters of 10 to 12 inches
(25 to 30 cm), or to some limited-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.
5-66

Wheel Alignment and Tire Balance
The tires and wheels on your vehicle were aligned and
balanced carefully at the factory to give you the longest
tire life and best overall performance. Adjustments to
wheel alignment and tire balancing will not be necessary
on a regular basis. However, if you notice unusual tire
wear or your vehicle pulling to one side or the other, the
alignment may need to be checked. If you notice your
vehicle vibrating when driving on a smooth road, your
tires and wheels may need to be rebalanced. See your
dealer for proper diagnosis.
Wheel Replacement
Replace any wheel that is bent, cracked, or badly rusted
or corroded. If wheel nuts keep coming loose, the wheel,
wheel bolts, and wheel nuts should be replaced. If the
wheel leaks air, replace it (except some aluminum
wheels, which can sometimes be repaired). See your
dealer if any of these conditions exist.
Your dealer will know the kind of wheel you need.
Each new wheel should have the same load-carrying
capacity, diameter, width, offset and be mounted
the same way as the one it replaces.
If you need to replace any of your wheels, wheel bolts,
or wheel nuts, replace them only with new GM original
equipment parts. This way, you will be sure to have the
right wheel, wheel bolts, and wheel nuts for your vehicle.
5-68