Pontiac 2009 G3, Owner'S Manual

Page: 257 / 348

(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 5-57.
(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.
Tire Size
The following illustration shows an example of a
typical passenger car 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 70, as
shown in item C of the illustration, it would mean
that the tire’s sidewall is 70% as high as it is wide.
(D) 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;
and the letter B means belted-bias ply construction.
(E) Rim Diameter
:
Diameter of the wheel in
inches.
(F) Service Description
:
These characters
represent the load index and speed rating of the
tire. The load index represents the load carry
capacity a tire is certified to carry. The speed
rating is the maximum speed a tire is certified
to carry a load.
5-53