CHEVROLET 2010 Express - Manual (Page 335)

(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) Load Range : Load Range.
(G) Service Description : The service description
indicates the load index and speed rating of a tire.
If two numbers are given as in the example,
120/116, then this represents the load index for
single versus dual wheel usage (single/dual).
The speed rating is the maximum speed a tire is
certified to carry a load. This does not apply to
Goodyear LT225/75R16 G949 RSA and Goodyear
LT225/75R16 G933 RSD commercial truck tires;
see the dual tire and single tire maximum load and
load range letter designations on the tire sidewall.
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.
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.
Bias Ply Tire : A pneumatic tire in which the plies
are laid at alternate angles less than 90 degrees
to the centerline of the tread.
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