Saturn 2007 Ion Owner's Manual page 331

(B) TPC Spec (Tire Performance Criteria
Specification): 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 Identification Number (TIN): The letters
and numbers following DOT (Department of
Transportation) code is 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 see Uniform Tire Quality Grading on
page 344.
(G) Maximum Cold Inflation Load Limit:
Maximum load that can be carried and the
maximum pressure needed to support that load.
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