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 booster
The brake booster uses engine manifold
vacuum to assist braking force. Do not
turn off the engine while driving because
that will turn off the brake booster, resulting
in poor braking power.
...
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• Promptly wipe the aluminum wheels clean of any kind of grime or agent. If dirt is left on too long, it may be difficult to clean off.
• Do not use soap containing grit to clean the wheels. Be sure ...
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Other bulbs may be difficult to replace. We recommend that you have the bulbs
replaced by your SUBARU dealer if necessary. ...
