Consumer information and Reporting safety defects

Tire size

~2min read

Your vehicle comes equipped with P-Metric tire size. It is important to understand the sizing system in selecting the proper tire for your vehicles. Here is a brief review of the tire sizing system with a breakdown of its individual elements.

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

(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

! Load and Speed Rating Descriptions

The load and speed rating descriptions will appear following the size designation.

They provide two important facts about the tire. First, the number designation is its load index. Second, the letter designation indicates the tire’s speed rating.

Example:

(6) Load Index: A numerical code which specifies the maximum load a tire can

(6) Load Index: A numerical code which specifies the maximum load a tire can carry at the speed indicated by its speed symbol, at maximum inflation pressure.

For example, “91” means 1,356 lbs (615 kg), “90” means 1,323 lbs (600 kg), “89” means 1,279 lbs (580 kg)

WARNING

Load indices apply only to the tire, not to the vehicle. Putting a load rated tire on any vehicle does not mean the vehicle can be loaded up to the tire’s rated load.

(7) Speed Rating: An alphabetical system describing a tire’s capability to travel at established and predetermined speeds.

For example, “V” means 240 km/h

WARNING

● Speed ratings apply only to the tire, not to the vehicle. Putting a speed rated tire on any vehicle does not mean the vehicle can be operated at the tire’s rated speed.

● The speed rating is void if the tires are worn out, damaged, repaired, retreaded, or otherwise altered from their original condition. If tires are repaired, retreaded, or otherwise altered, they may not be suitable for original equipment tire designed loads and speeds.

Test yourself

A quick Subaru Legacy quiz: every answer comes with an explanation and a link to the manual page.