GMC 2011 Sierra - Manual (Page 486)

Black plate (62,1) GMC Sierra Owner Manual - 2011
10-62 Vehicle Care
(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 75, as shown
in item C of the light truck
(LT‐Metric) tire illustration,
it would mean that the tire's
sidewall is 75 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) 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.
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).
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.