Tire Size
The following examples show the different parts of a
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 “75,” as shown in item “C” of
the illustration, it would mean that the tire’s sidewall
is 75% 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:The service description
indicates the load range and speed rating of a tire. The
load index can range from 1 to 279. Speed ratings
range from “A” to “Z”. The light truck tire size example
above shows dual or single tire configurations. Passenger (P-Metric) Tire
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(A) Light Truck (LT-Metric) Tire:The United States
version of a metric tire sizing system. The letter “LT” as
the first two characters in the tire size means a light
truck 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 “75,” as shown in item “C” of
the illustration, it would mean that the tire’s sidewall is
75% 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:The service description
indicates the load range and speed rating of a tire. The
load index can range from 1 to 279. Speed ratings
range from “A” to “Z”. The light truck tire size example
above shows dual or single tire configurations.
Light Truck (LT-Metric) Tire
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Tire Inspection and Rotation
Tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km).
Any time you notice unusual wear, rotate your tires as
soon as possible and check wheel alignment. Also
check for damaged tires or wheels. SeeWhen It Is Time
for New Tires on page 5-75andWheel Replacement
on page 5-78for more information.
Make sure the spare tire is stored securely. Push, pull,
and then try to rotate or turn the tire. If it moves,
use the wheel wrench to tighten the cable. See
Changing a Flat Tire on page 5-82.
The purpose of regular rotation is to achieve more
uniform wear for all tires on the vehicle. The first rotation
is the most important. SeePart A: Scheduled
Maintenance Services on page 6-4, for scheduled
rotation intervals.When rotating your tires, always use the correct rotation
pattern shown here.
If your vehicle has a compact spare tire or a spare tire
that does not match your vehicle’s road tires and
wheels, in size and type, do not include the spare in the
tire rotation.
After the tires have been rotated, adjust the front and
rear inflation pressures as shown on the
Certification/Tire label or the Tire and Loading
Information label. Make certain that all wheel nuts are
properly tightened. See “Wheel Nut Torque” under
Capacities and Speci cations on page 5-111.
5-74
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make wheel nuts
become loose after a time. The wheel could
come off and cause an accident. When you
change a wheel, remove any rust or dirt from
places where the wheel attaches to the vehicle.
In an emergency, you can use a cloth or a
paper towel to do this; but be sure to use a
scraper or wire brush later, if you need to, to
get all the rust or dirt off. See “Changing a Flat
Tire” in the Index.
When It Is Time for New Tires
One way to tell when it’s
time for new tires is to
check the treadwear
indicators, which will
appear when your tires
have only 1/16 inch
(1.6 mm) or less of tread
remaining. Some
commercial truck tires may
not have treadwear
indicators.
You need a new tire if any of the following statements
are true:
•You can see the indicators at three or more places
around the tire.
•You can see cord or fabric showing through the
tire’s rubber.
•The tread or sidewall is cracked, cut or snagged
deep enough to show cord or fabric.
•The tire has a bump, bulge or split.
•The tire has a puncture, cut or other damage that
can’t be repaired well because of the size or
location of the damage.
5-75
Buying New Tires
To find out what kind and size of tires you need, look at
the Certification/Tire label or Tire and Loading
Information label.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Specification (TPC Spec)
number on each tire’s sidewall. When you get new tires,
GM recommends that you get tires with that same
TPC Spec number. That way your vehicle will continue
to have tires that are designed to give proper
endurance, handling, speed rating, traction, ride and
other things during normal service on your vehicle.
If your tires have an all-season tread design, the TPC
number will be followed by an “MS” (for mud and snow).
If you ever replace your tires with those not having a
TPC Spec number, make sure they 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 (if you have one). It was
developed for use on your vehicle.
{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.
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Tire Chains
{CAUTION:
Don’t use tire chains. There’s not enough
clearance. Tire chains used on a vehicle
without the proper amount of clearance can
cause damage to the brakes, suspension or
other vehicle parts. The area damaged by the
tire chains could cause you to lose control of
your vehicle and you or others may be injured
in a crash. Use another type of traction device
CAUTION: (Continued)
CAUTION: (Continued)
only if its manufacturer recommends it for use
on your vehicle and tire size combination and
road conditions. Follow that manufacturer’s
instructions. To help avoid damage to your
vehicle, drive slowly, readjust or remove the
device if it’s contacting your vehicle, and don’t
spin your wheels. If you do nd traction
devices that will t, install them on the
rear tires.
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Compact Spare Tire
Although the compact spare tire was fully inflated when
your vehicle was new, it can lose air after a time.
Check the inflation pressure regularly. It should be
60 psi (420 kPa).
After installing the compact spare on your vehicle, you
should stop as soon as possible and make sure
your spare tire is correctly inflated. The compact spare
is made to perform well at speeds up to 65 mph
(105 km/h) for distances up to 3,000 miles (5 000 km),
so you can finish your trip and have your full-size
tire repaired or replaced where you want. Of course, it’s
best to replace your spare with a full-size tire as
soon as you can. Your spare will last longer and be in
good shape in case you need it again.
Notice:When the compact spare is installed, don’t
take your vehicle through an automatic car wash
with guide rails. The compact spare can get caught
on the rails. That can damage the tire and wheel,
and maybe other parts of your vehicle.
Don’t use your compact spare on other vehicles.
And don’t mix your compact spare tire or wheel with
other wheels or tires. They won’t fit. Keep your spare tire
and its wheel together.
Notice:Tire chains won’t t your compact spare.
Using them can damage your vehicle and can
damage the chains too. Don’t use tire chains on
your compact spare.
Appearance Care
Remember, cleaning products can be hazardous. Some
are toxic. Others can burst into flames if you strike a
match or get them on a hot part of the vehicle. Some are
dangerous if you breathe their fumes in a closed
space. When you use anything from a container to clean
your vehicle, be sure to follow the manufacturer’s
warnings and instructions. And always open your doors
or windows when you are cleaning the inside.
Never use these to clean your vehicle:
•Gasoline
•Benzene
•Naphtha
•Carbon Tetrachloride
•Acetone
•Paint Thinner
•Turpentine
•Lacquer Thinner
•Nail Polish Remover
They can all be hazardous — some more than others —
and they can all damage your vehicle, too.
5-94
Time Delay....................................................2-31
Tire Inflation Check.........................................6-25
Tire Sidewall Labeling......................................5-62
Tire Size.......................................................5-68
Tire Terminology and Definitions........................5-70
Tires.............................................................5-61
Buying New Tires........................................5-76
Chains.......................................................5-80
Changing a Flat Tire....................................5-82
Compact Spare Tire.....................................5-94
If a Tire Goes Flat.......................................5-81
Inflation - Tire Pressure................................5-72
Inspection and Rotation................................5-74
Uniform Tire Quality Grading.........................5-77
Wheel Alignment and Tire Balance.................5-78
Wheel Replacement.....................................5-78
When It Is Time for New Tires......................5-75
To Use the Engine Coolant Heater....................2-19
Top Strap......................................................1-37
Top Strap Anchor Location...............................1-38
Torque Lock...................................................2-28
Total Weight on Your Vehicle’s Tires..................4-55
Towing
Recreational Vehicle.....................................4-42
Towing a Trailer..........................................4-51
Your Vehicle...............................................4-42
Trailer
Recommendations.......................................4-51
Trailer Brakes.................................................4-57Transfer Case........................................2-23, 5-50
Transfer Case and Front Axle
(Four-Wheel Drive) Inspection.......................6-31
Transmission
Fluid, Automatic...........................................5-20
Transmission Operation, Automatic....................2-20
Transmission, Transaxle, Transfer Case Unit
Repair Manual............................................7-11
Transportation Options...................................... 7-8
Traveling to Remote Areas...............................4-16
Trip Odometer................................................3-25
Truck-Camper Loading Information....................4-49
Turn and Lane-Change Signals.......................... 3-6
Turn Signal/Multifunction Lever........................... 3-6
Turn Signals When Towing a Trailer..................4-58
Two-Piece Composite Headlamp System............5-54
Two-Tiered Loading.........................................4-48
U
Underbody Flushing Service.............................6-29
Understanding Radio Reception........................3-76
Uniform Tire Quality Grading............................5-77
United States – Customer Assistance.................. 7-4
Used Replacement Wheels..............................5-79
Using Cleaner on Fabric..................................5-95
Using Song List Mode.....................................3-73
Using the Recovery Hooks...............................4-41
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