Tire Size
The following illustrations show the different parts of a
tire size code.
(A) 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.
(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 illustration, it would mean that the tire’s sidewall
is 75% as high as it is wide.
(D) Belt Rating 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) Service Description: The service description
indicates the load range and speed rating of a tire.
The load index can range from 1 to 279. Speed ratings
range from “A” to “Z”. The light truck tire size example
above shows dual or single tire configurations.
Passenger (P-Metric) Tire
5-64
To Next Page
Loading...
