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Cadillac XT5 Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
16406251) - 2023 - CRC - 3/28/22
Vehicle Care
381
letter
“
T
”
as the first
character in the tire size
means the tire is for
temporary use only.
(7) 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.
Tire Designations
Tire Size
The example shows a
typical passenger vehicle
tire size.
Passenger (P-Metric) Tire
(1) 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.
(2) Tire Width
:
The 3-digit
number indicates the tire
section width in millimeters
from sidewall to sidewall.
(3) Aspect Ratio
:
A 2-digit
number that indicates the
tire height-to-width
measurements. For
example, if the tire size
aspect ratio is 75, as
shown in item (3) of the
illustration, it would mean
that the tire's sidewall is
75 percent as high as it
is wide.
(4) 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.
(5) Rim Diameter
:
Diameter of the wheel in
inches.
(6) Service Description
:
These characters
represent the load index
and speed rating of the
tire. The load index
represents the load
carrying capacity a tire is
certified to carry. The