GMC Sierra Classic 2007 Owner's Manual page 542

Light Truck (LT-Metric) Tire
(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.
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(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) 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 Inflation - Tire Pressure on
page 547 and Loading Your Vehicle on page 403.
(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 Identification 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.