(A) Tire Size:The tire size code 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 ªTire Sizeº illustration
later in this section for more detail.
(B) Tire Performance Criteria Speci®cation (TPC
Spec):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) Dual Tire Maximum Load:Maximum load that can
be carried and the maximum pressure needed to
support that load when used in a dual con®guration. For
information on recommended tire pressure see
In¯ation - Tire Pressure on page 5-71andLoading Your
Vehicle on page 4-47.
(D) Department of Transportation (DOT):The
Department of Transportation (DOT) code indicates that
the tire is in compliance with the U.S. Department of
Transportation Motor Vehicle Safety Standards.
(E) Tire Identi®cation Number (TIN):The letters and
numbers following DOT code are 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.
LT-Metric Tire
5-66
(F) Tire Ply Material:The type of cord and number of
plies in the sidewall and under the tread.
(G) Single Tire Maximum Load:Maximum load
that can be carried and the maximum pressure needed
to support that load when used as a single. For
information on recommended tire pressure see
In¯ation - Tire Pressure on page 5-71andLoading
Your Vehicle on page 4-47.
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 ªPº 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 ª75,º as shown in item ªCº 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 ªRº means radial ply construction; the letter ªDº
means diagonal or bias ply construction; and the
letter ªBº 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 ªAº to ªZº.
Passenger (P-Metric) Tire
5-67
(A) Light Truck (LT-Metric) Tire:The United States
version of a metric tire sizing system. The letter ªLTº as
the ®rst 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 ª75,º as shown in item ªCº 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 ªRº means radial ply construction; the letter ªDº
means diagonal or bias ply construction; and the
letter ªBº 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 ªAº to ªZº. The light truck tire size example
above shows dual or single tire con®gurations.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. Light Truck (LT-Metric) Tire
5-68
TPM Sensor Identi®cation Codes
Each TPM sensor has a unique identi®cation code. Any
time you rotate your vehicle's tires or replace one or
more of the TPM sensors, the identi®cation codes
will need to be matched to the new tire/wheel position.
Each tire/wheel position is matched to a sensor, by
increasing or decreasing the tire's air pressure.
The sensors are matched to the tire/wheel positions in
the following order: left front (LF); right front (RF);
right rear (RR) and left rear (LR).
You will have one minute to match the ®rst tire/wheel
position, and ®ve minutes overall to match all four
tire/wheel positions. If it takes longer than one minute,
to match the ®rst tire and wheel, or more than ®ve
minutes to match all four tire and wheel positions the
matching process stops and you will need to start over.
The TPM sensor matching process is outlined below:
1. Set the Parking brake.
2. Turn the ignition switch to RUN with the engine off.3. Turn the exterior lamp switch from ªOffº to ªOnº
four times within 3 seconds. A double horn chirp
will sound and the TPM low tire warning light
will begin to ¯ash. The double horn chirp and
¯ashing TPM warning light indicate that the TPM
matching process has started. The TPM warning
light should continue ¯ashing throughout the
matching procedure. The SERVICE TIRE
MONITOR message will be displayed on the Driver
Information Center (DIC).
4. Start with the left (driver's side) front tire.
5. Remove the valve cap from the valve cap stem.
Activate the TPM sensor by increasing or
decreasing the tire's air pressure for 10 seconds,
then stop and listen for a single horn chirp.
The single horn chirp should sound within
15 seconds, con®rming that the sensor identi®cation
code has been matched to this tire and wheel
position. If you do not hear the con®rming single
horn chirp, you will need to start over with step
number one. To let air-pressure out of a tire you can
use the pointy end of the valve cap, a pencil-style
air pressure gage or a key.
5-73
6. Proceed to the right (passenger's side) front tire,
and repeat the procedure in step 5.
7. Proceed to the right (passenger's side) rear tire,
and repeat the procedure in step 5.
8. Proceed to the left (driver's side) rear tire, and
repeat the procedure in step 5.
9. After hearing the con®rming horn chirp for the left
rear tire, check to see if the TPM warning light is
still ¯ashing. If yes, turn the ignition switch to OFF.
10. Set all four tires to the recommended air pressure
level as indicated on the Certi®cation/Tire label or
the Tire and Loading Information label.
11. Put the valve caps back on the valve stems
The spare tire does not have a TPM sensor. If you
replace one of the road tires with the spare, the CHECK
TIRE PRESSURE message will be displayed on the
DIC screen. This message should go off once you
re-install the road tire containing the TPM sensor. The
SERVICE TIRE MONITOR message is displayed
when the TPM system is malfunctioning. One or more
missing or inoperable TPM sensors will cause the
service tire monitor message to be displayed. See your
dealer for service.Federal Communications Commission and
Industry and Science Canada
The TPM system operates on a radio frequency subject
to Federal Communications Commission (FCC) Rules
and with Industry and Science Canada.
This device complies with Part 15 of the FCC Rules and
with RSS-210 of Industry and Science Canada.
Operation is subject to the following two conditions: (1)
This device may not cause harmful interference, and
(2) this device must accept any interference received
including interference that may cause undesired
operation of the device.
Changes or modi®cations to this system by other than
an authorized service facility could void authorization to
use this equipment.
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. See
When It Is Time
for New Tires on page 5-76andWheel Replacement
on page 5-80for more information.
5-74
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.
Buying New Tires
To ®nd out what kind and size of tires you need, look at
the Certi®cation/Tire label or the Tire and Loading
Information label. See
Loading Your Vehicle on
page 4-47, for more information about these labels and
where they can be found on your vehicle.
The tires installed on your vehicle when it was
new had a Tire Performance Criteria Speci®cations
(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, load
range, traction, ride, tire pressure monitoring system
performance 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 ªMSº
(for mud and snow).
5-76
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, 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.
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. Warning: The traction grade
assigned to this tire is based on straight-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.
5-78
Vehicle Identi®cation
Vehicle Identi®cation Number (VIN)
This is the legal identi®er for your vehicle. It appears on
a plate in the front corner of the instrument panel, on
the driver's side. You can see it if you look through the
windshield from outside your vehicle. The VIN also
appears on the Vehicle Certi®cation and Service Parts
labels and the certi®cates of title and registration.
Engine Identi®cation
The 8th character in your VIN is the engine code. This
code will help you identify your engine, speci®cations
and replacement parts.
Service Parts Identi®cation Label
You'll ®nd this label located in the glove box. It's very
helpful if you ever need to order parts. On this label is:
·your VIN,
·the model designation,
·paint information and
·a list of all production options and special
equipment.
Be sure that this label is not removed from the vehicle.
5-110