Operation Manual

Tires
9-18 Vehicle care and maintenance
9
 Sidewall: portion of a tire between the
tread and bead.
 Section width: the linear distance between
the exteriors of the sidewalls of an
inflated tire, excluding elevations due to
labeling, decoration, or protective bands.
 Bead: the part of the tire that is made of
steel wires, wrapped or reinforced by ply
cords and that is shaped to fit the rim.
 Ply: a layer of rubber-coated parallel
cords.
 Cord: the strands forming the plies in the
tire.
 Rim: a metal support for a tire or a tire
and tube assembly upon which the tire
beads are seated.
 Rim diameter: nominal diameter of the
bead seat.
 Groove: the space between two adjacent
tread ribs.
EXAMPLE:P215/65R15
Tire Markings
Size Designation
P
Passenger car tire size based
on U.S.A. design standards
215
Section width in millimeters
(mm.)
65
Aspect ratio in percent (%)
Ratio of section height to sec-
tion width of tire.
R
Construction code
•“R” means radial construc-
tion.
•“D” means diagonal or bias
construction.
15 Rim diameter in inches (in)
NOTE
 European/Japanese metric tire
sizing is based on European/Jap-
anese design standards. Tires
designed to these standards have
the tire size molded into the
sidewall beginning with the sec-
tion width. The letter “P” is
absent from this tire size desig-
nation. Example: 215/65R15
96H.