GMC 2008 Canyon - Manual (Page 319)

Tire Size
The following illustration shows an example of a
typical passenger vehicle tire size.
(A) 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 percent 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 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.
Tire Terminology and Definitions
Air Pressure : The amount of air inside the
tire pressing outward on each square inch of
the tire. Air pressure is expressed in pounds per
square inch (psi) or kilopascal (kPa).
Accessory Weight : This means the combined
weight of optional accessories. Some examples of
optional accessories are, automatic transmission,
power steering, power brakes, power windows,
power seats, and air conditioning.
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