Tire Terminology And Definitions - Chevrolet 2007 Optra Owner's Manual

(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 range and the speed rating
of a tire. The load range 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. 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/transaxle, power steering, power
brakes, power windows, power seats, and
air conditioning.
Aspect Ratio: The relationship of a tire's height
to its width.
Belt: A rubber coated layer of cords that is located
between the plies and the tread. Cords may be
made from steel or other reinforcing materials.
Bead: The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the rim.
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