GMC 2007 Canyon - Manual (Page 373)

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.
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