{CAUTION
You can be seriously injured by
not wearing the lap-shoulder belt
properly. In a crash, you would not
be restrained by the shoulder belt.
Your body could move too far
forward increasing the chance of
head and neck injury. You might
also slide under the lap belt.
The belt force would then be
applied right on the abdomen.
That could cause serious or fatal
injuries. The shoulder belt should
go over the shoulder and across
the chest.
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/retailer to fix it.
Seats and Restraints 2-17
Tire Sidewall Labeling
Useful information about a
tire is molded into its sidewall.
The examples 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 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 (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. (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 9-58.
(F) 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
9-44 Vehicle Care
(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 aregular road tire has lost air and
gone flat. If your vehicle has a
compact spare tire. See
Compact
Spare Tire on page 9-68 andIf a
Tire Goes Flat on page 9-62 .
(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 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.
(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 Tire Pressure on
page 9-49.
(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
Vehicle Care 9-45
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
certified to carry. The speed
rating is the maximum speed a
tire is certified to carry a load.
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.
Belt
:A rubber coated layer of
cords that is located between the
plies and the tread. Cords may
be made from steel or other
reinforcing materials.
9-46 Vehicle Care
Different Size Tires and
Wheels
If you add wheels or tires that are
a different size than your original
equipment wheels and tires, this
could 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.
SeeBuying New Tires on page 9-56
and Accessories and Modi cations
on page 9-3 for 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.
9-58 Vehicle Care
Wheel Alignment and
Tire Balance
The tires and wheels on the vehicle
were aligned and balanced carefully
at the factory to give 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 there
is unusual tire wear or the vehicle
pulls to one side or the other, the
alignment should be checked. If the
vehicle vibrates when driving on a
smooth road, the tires and wheels
might need to be rebalanced.
See your dealer/retailer 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/retailer if any of these
conditions exist.
Your dealer/retailer 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 the
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 the vehicle.{CAUTION
Using the wrong replacement
wheels, wheel bolts, or wheel
nuts on your vehicle can be
dangerous. It could affect the
braking and handling of your
vehicle, make your tires lose
air and make you lose control.
You could have a collision in
which you or others could be
injured. Always use the correct
wheel, wheel bolts, and wheel
nuts for replacement.
Notice: The wrong wheel can
also cause problems with bearing
life, brake cooling, speedometer
or odometer calibration, headlamp
aim, bumper height, vehicle
ground clearance, and tire or tire
chain clearance to the body and
chassis.
See If a Tire Goes Flat on page 9-62
for more information.
9-60 Vehicle Care