Page 27 of 316
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.
To unlatch the belt, just push the button on the buckle.
The belt should go back out of the way.
1-21
Page 226 of 316

Tire Sidewall Labelling
Useful information about a tire is molded into its
sidewall. The examples below show a typical passenger
car tire and a compact spare tire sidewall.
(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) 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.
(C) Tire Identi cation Number (TIN):The letters and
numbers following DOT code are 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.
(D) Tire Ply Material:The type of cord and number of
plies in the sidewall and under the tread.
(E) 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 see
Uniform Tire Quality Grading on page 5-56.
(F) Maximum Cold In ation Load Limit:Maximum
load that can be carried and the maximum pressure
needed to support that load. For information on
recommended tire pressure seeInflation - Tire Pressure
on page 5-53andLoading Your Vehicle on page 4-28. Passenger Car Tire Example
5-48
Page 227 of 316

(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 flat. SeeCompact Spare Tire on
page 5-68andIf a Tire Goes Flat on page 5-60.(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 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.
(D) Maximum Cold In ation Load Limit:Maximum
load that can be carried and the maximum pressure
needed to support that load. SeeCompact Spare Tire
on page 5-68andLoading Your Vehicle on page 4-28.
(E) Tire In ation:The temporary use tire or compact
spare tire should be inflated to 60 psi (420 kPa).
For more information on tire pressure and inflation see
Inflation - Tire Pressure on page 5-53.
(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. Compact Spare Tire Example
5-49
Page 228 of 316

Tire Size
The following illustration shows an example of a typical
passenger car 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 70, as shown in item C of
the illustration, it would mean that the tire’s sidewall
is 70% 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 the speed rating of a tire. The
load range represents the load carry capacity a tire is
certified to carry. The speed rating is the maximum
speed a tire is certified 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.
5-50
Page 234 of 316

Buying New Tires
To find out what kind and size of tires you need, look at
the tire and loading information label attached to your
vehicle. SeeLoading Your Vehicle on page 4-28for a
label example and where it is attached to your vehicle.
Make sure the replacements are the same size,
load range, speed rating and construction type
(bias, bias-belted or radial) as your original tires.
{CAUTION:
Mixing tires could cause you to lose control
while driving. If you mix tires of different sizes
or types (radial and bias-belted tires), the
vehicle may not handle properly, and you
could have a crash. Using tires of different
sizes may also cause damage to your vehicle.
Be sure to use the same size and type tires
on all wheels. It’s all right to drive with your
compact spare temporarily, it was developed
for use on your vehicle. SeeCompact Spare
Tire on page 5-68.
{CAUTION:
If you use bias-ply tires on your vehicle, the
wheel rim anges could develop cracks after
many miles of driving. A tire and/or wheel
could fail suddenly, causing a crash. Use only
radial-ply tires with the wheels on your vehicle.
Uniform Tire Quality Grading
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
selection width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the Unites States National Highway Traffic
Safety Administration, 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 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.
5-56
Page 236 of 316

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.
5-58