Page 30 of 452
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.
30
Page 341 of 452

Tire Sidewall Labeling
Useful information about a tire is molded into the
sidewall. The following illustrations are examples
of a typical P-Metric and a LT-Metric tire sidewall.(A) Tire Size:The tire size code 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) TPC Spec (Tire Performance Criteria
Speci cation):Original equipment tires designed
to GM’s specific tire performance criteria have
a TPC specification code molded onto the sidewall.
GM’s TPC specifications 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 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.
Passenger (P-Metric) Tire
341
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(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 356.
(G) 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 seeIn ation - Tire Pressure on page 348
andLoading Your Vehicle on page 259.
(A) Tire Size:The tire size code 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.
Light Truck (LT-Metric) Tire
342
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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.(A) Light Truck (LT-Metric) Tire:The United
States version of a metric tire sizing system. The
letters 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 light truck (LT-Metric) tire
illustration, it would mean that the tire’s sidewall is
75 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: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.
Passenger (P-Metric) Tire
Light Truck (LT-Metric) Tire
344
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