
Tires
Your new vehicle comes with high-quality tires
made by a leading tire manufacturer. If you ever
have questions about your tire warranty and where
to obtain service, see your GM Warranty booklet for
details. For additional information refer to the tire
manufacturer’s booklet included with your vehicle.
{CAUTION:
Poorly maintained and improperly used
tires are dangerous.
Overloading your vehicle’s tires can
cause overheating as a result of too
much friction. You could have an
air-out and a serious accident. See
Loading Your Vehicle on page 259.
CAUTION: (Continued)
CAUTION: (Continued)
Underin ated tires pose the same
danger as overloaded tires. The
resulting accident could cause serious
injury. Check all tires frequently to
maintain the recommended pressure.
Tire pressure should be checked when
your vehicle’s tires are cold. See
Inflation - Tire Pressure on page 348.
Overin ated tires are more likely to be
cut, punctured, or broken by a sudden
impact — such as when you hit a
pothole. Keep tires at the
recommended pressure.
Worn, old tires can cause accidents. If
the tire’s tread is badly worn, or if
your vehicle’s tires have been
damaged, replace them.
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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
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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
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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
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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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