P Metric
With the P-Metric system, Section Width is measured in millimeters.
To convert millimeters into inches, divide by 25.4. The Aspect Ratio (Section Height divided by Section Width) helps provide more dimensional information about the tire size.
Example:

(1) P = Certain tire type used on light duty vehicles such as passenger
cars
(2) Section Width in millimeters
(3) Aspect Ratio (= section height 7 section width).
(4) R = Radial Construction
(5) Rim diameter in inches
See also:
Tire Identification Number (TIN)
Tire Identification Number (TIN) is
marked on the intended outboard
sidewall. The TIN is composed of
four groups. Here is a brief review
of the TIN with a breakdown of its
individual element ...
Outside mirrors
Outside mirrors ...
Sport (S) mode
For all-around performance driving
The Sport (S) mode provides the engine power desired by those who want to make the driving experience their own personal adventure.
The linear acceleration charact ...
