Pontiac 2008 G8 Owner's Manual page 226

9-42 Vehicle Service and Care
(E) Tire Inflation The
:
temporary use tire or compact
spare tire should be inflated
to 60 psi (420 kPa). For
more information on tire
pressure and inflation see
Inflation - Tire Pressure on
page 9-46.
(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
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 Size
The following illustration shows
an example of a typical
passenger vehicle tire size.
(A) 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.
(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 60, as shown in
item C of the illustration, it would
mean that the tire's sidewall is
60 percent as high as it is wide.
(D) Construction Code
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
the wheel in inches.
(F) Service Description
characters represent the load
range and speed rating of the
tire. The load index represents
the load carry capacity a tire is
certified to carry. The load index
can range from 1 to 279. The
speed rating is the maximum
speed a tire is certified to carry a
load. Speed ratings range from
A to Z.
A letter
:
Diameter of
:
These
: