The Writing on the Wall

Tires have a wealth of information encoded on their sidewalls. When replacing them, we recommend staying with the size and speed rating of your car’s original tires. Consult your owner’s manual for additional information.


On the tire at right, “215” is the cross-section width in millimeters; 60 is the ratio of sidewall height to its width (60 percent); R indicates radial-ply construction; and 16 is the wheel rim’s diameter in inches.

Load index

'Shorthand for the weight each tire can carry safely. The 94 here means 1,477 pounds per tire­—pretty typical for a midsized car tire. That’s the maximum tire load at the maximum pressure.

Speed rating

A letter denoting the tire’s maximum speed when carrying the load defined by the load index­—and not how fast you should drive! Standard all-seasons are usually rated S (112 mph) or T (118 mph). Climbing up the scale are the letters H (130 mph), V (149 mph), ZR (149+ mph), W (168 mph), and Y (186 mph). Winter tires may carry the letter Q (99 mph) or higher.

Treadwear grade

A government-required number that indicates a tire’s expected wear. A grade of 300 denotes a tire that will wear three times as well as a tire graded 100. But the numbers are assigned by tire manufacturers, not an independent third party.

Traction and temperature scores

Those scores denote a tire’s wet-stopping ability and temperature resistance. For traction, AA is best, C is worst. For temperature resistance, scores range from A (best) to C.