GMC YUKON XL 2004 Owner's Manual page 444

(A) Tire Size Code: 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 Code" illustration
later in this section for more detail.
(B) Tire Performance Criteria Specification (TPC
Spec): 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) Department of Transportation (DOT): 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 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.
P-Metric Tire
5-64