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:
Difference between screen and actual road
The distance markers show the distance for a level road when the vehicle is not
loaded. It may be different from the actual distance depending on the loading conditions
or road conditions.
When t ...
Windshield wiper and washer switches
The wiper operates only when the ignition switch is in the “ON” position. ...
Determining compatibility of tire and vehicle load capacities
The sum of four tires’ maximum load ratings must exceed the maximum loaded vehicle weight (“GVWR”). In addition, sum of the maximum load ratings of two front tires and of two rear tires must exceed ea ...
