{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 x it.
Seats and Restraints 1-17
ProCarManuals.com
4. At a wall, measure from the
ground upward (A) to the
recorded distance from Step 3
and mark it.
5. Draw or tape a horizontal line (B)
on the wall the width of the
vehicle at the height of the mark
in Step 4.Notice:Do not cover a headlamp
to improve beam cut-off when
aiming. Covering a headlamp may
cause excessive heat build-up
which may cause damage to the
headlamp.
6. Turn on the low-beam headlamps
and place a piece of cardboard
or equivalent in front of the
headlamp not being adjusted.
Do not place it directly on
the headlamp. This allows only
the beam of light from the
headlamp being adjusted to be
seen on the at surface.7. Locate the vertical headlamp
aiming screws, which are
under the hood near each
headlamp assembly.
The adjustment screw can be
turned with a 6 mm socket
wrench.
8. Turn the vertical aiming screw
until the headlamp beam is
aimed to the horizontal
tape line. Turn it clockwise or
counterclockwise to raise
or lower the angle of the beam.
Vehicle Service and Care 9-27
ProCarManuals.com
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 9-57.
(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
9-42 Vehicle Service and Care
ProCarManuals.com
(A) Tire Ply Material:The type
of cord and number of plies in the
sidewall and under the tread.
(B) 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 50 mph
(80 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 9-68andIf a Tire
Goes Flat on page 9-60.
(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
seeInflation - Tire Pressure on
page 9-47.(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
Vehicle Service and Care 9-43
ProCarManuals.com
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 index and speed rating
of the tire. The load index
represents the load carry
capacity a tire is certi ed to
carry. The speed rating is the
maximum speed a tire is certi ed
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.
9-44 Vehicle Service and Care
ProCarManuals.com
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.
Treadwear
The treadwear grade is a
comparative rating based on
the wear rate of the tire
when tested under controlled
conditions on a speci ed
government test course.For example, a tire graded 150
would wear one and a half (1.5)
times as well on the government
course as a tire graded 100.
The relative performance of tires
depends upon the actual
conditions of their use, however,
and may depart signi cantly from
the norm due to variations in
driving habits, service practices,
and differences in road
characteristics and climate.
Traction – AA, A, B, C
The traction grades, from highest
to lowest, are AA, A, B, and C.
Those grades represent the
tire’s ability to stop on wet
pavement as measured under
controlled conditions on
speci ed government test
surfaces of asphalt and
concrete. A tire marked C may
have poor traction performance.
Vehicle Service and Care 9-57
ProCarManuals.com
Wheel Replacement
Replace any wheel that is bent,
cracked or badly rusted or corroded.
If the wheel bolts keep coming
loose, the wheel and wheel bolts
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 or wheel bolts, replace them
only with new GM original equipment
parts. This way, you will be sure to
have the right wheel and wheel bolts
for the vehicle.{CAUTION
Using the wrong replacement
wheels or wheel bolts on your
vehicle can be dangerous. It could
affect the braking and handling of
the vehicle, make the tires lose air
and make you lose control of
the vehicle. You could have a
collision in which you or others
could be injured. Always use the
correct wheel and wheel bolts 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.
SeeChanging a Flat Tire on
page 9-61for more information.
Used Replacement Wheels
{CAUTION
Putting a used wheel on the
vehicle is dangerous. You cannot
know how it has been used or
how far it has been driven.
It could fail suddenly and cause a
crash. If you have to replace a
wheel, use a new GM original
equipment wheel.
Vehicle Service and Care 9-59
ProCarManuals.com