Tire Terminology And Definitions - Cadillac ATS 2017 Owner's Manual

328 VEHICLE CARE
(1) 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.
(2) Tire Width The three-digit
:
number indicates the tire section
width in millimeters from sidewall
to sidewall.
(3) 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 3 of
the illustration, it would mean
that the tire's sidewall is
60 percent as high as it is wide.
(4) Construction Code
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.
(5) Rim Diameter
the wheel in inches.
(6) Service Description
characters represent the load
index and speed rating of the tire.
The load index represents the load
carrying 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.
A letter Air pressure is expressed in kPa
:
(kilopascal) or psi (pounds per
square inch).
Accessory Weight
weight of optional accessories.
Some examples of optional
accessories are automatic
transmission, power windows,
Diameter of power seats, and air conditioning.
:
Aspect Ratio
These a tire's height to its width.
:
Belt
cords between the plies and the
tread. Cords may be made from
steel or other reinforcing
materials.
Bead
wires wrapped by steel cords that
hold the tire onto the rim.
Bias Ply Tire
which the plies are laid at
alternate angles less than
90 degrees to the centerline of the
tread.
The combined
:
The relationship of
:
A rubber coated layer of
:
The tire bead contains steel
:
A pneumatic tire in
: