Tire Sidewall Labeling
Useful information about a tire is molded into its
sidewall. The examples below show a typical
passenger vehicle tire and a compact spare tire
sidewall.(A) Tire Size
:The tire size 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.
Passenger Vehicle Tire Example
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(F) Tire Size:A combination of letters and
numbers define a tire’s width, height, aspect
ratio, construction type and service description.
The letter T as the first character in the tire
size means the tire is for temporary use only.
(G) 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.
Tire Size
The following illustration shows an example of a
typical passenger vehicle tire size.
(A) 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 70, as
shown in item C of the illustration, it would mean
that the tire’s sidewall is 70 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
:These characters
represent the load index and speed rating of the
tire. The load index represents the load carry
capacity a tire is certified to carry. The speed
rating is the maximum speed a tire is certified
to carry a load.
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