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Tire designations, Tire terminology and definitions, Tire designations -40 tire terminology and – Buick 2010 Enclave User Manual

Page 342: Definitions -40

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Vehicle Care

Tire Designations

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

:

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.

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 psi (pounds per
square inch) or kPa (kilopascal).