Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-16500442) -
2023 - CRC - 5/4/22
Vehicle Care
419
(2) Tire Width
:
The 3-digit
number indicates the tire
section width in millimeters
from sidewall to sidewall.
(3) Aspect Ratio
:
A 2-digit
number that indicates the
tire height-to-width
measurements. For
example, if the tire size
aspect ratio is 75, as
shown in item (3) of the
illustration, it would mean
that the tire's sidewall is
75 percent as high as it
is wide.
(4) 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.
(5) Rim Diameter
:
Diameter of the wheel in
inches.
(6) Service Description
:
These 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. Air
pressure is expressed
in kPa (kilopascal) or psi
(pounds per square inch).
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.
Cold Tire Pressure
:
The
amount of air pressure in a
tire, measured in kPa
(kilopascal) or psi (pounds
per square inch) before a
tire has built up heat from
driving. See Tire Pressure