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:
Brake pad and lining
While maintaining a speed of 30 to 40
mph (50 to 65 km/h), step on the brake
pedal lightly. Repeat this five or more
times. ...
Maximum permissible inflation pressure
The maximum cold inflation pressure
to which this tire may be
inflated. For example, “300 kPa
(44 PSI) MAX. PRESS” ...
Child restraint systems
Infants and small children should always be placed in an infant or child restraint
system in the rear seat while riding in the vehicle.
You should use an infant or child restraint system that mee ...
