
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.
(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 5-66.
(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 5-59andLoading Your Vehicle on page 4-30. Passenger (P-Metric) Tire
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(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) Dual Tire Maximum Load:Maximum load that can
be carried and the maximum pressure needed to
support that load when used in a dual configuration.
For information on recommended tire pressure see
In ation - Tire Pressure on page 5-59andLoading Your
Vehicle on page 4-30.
(D) 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.
(E) 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.
(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 5-59andLoading Your
Vehicle on page 4-30. Light Truck (LT-Metric) Tire
5-55

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% 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
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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 specified 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 significantly 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 specified 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.
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