Everything You Wanted to Know About Modern
But Didn't Know Who or What to Ask.
Howard V. Scotland, Jr.
How many times have you looked at all of the writing on the sidewalls of the tires on your modern car, truck or trailer and wondered what it all meant. Perhaps you have wanted to know more technical data about the tires you planned to buy or the ones you already have. The simple diagram below provides the answers to most of your questions and is provided through the courtesy of Bridgestone-Firestone.
|215||millimeter width of tire
LT tires in inches
|65||Ratio of height to tread width (higher
numbers mean smoother ride but sloppier handling.
LT tires do not give ratio, but tire diameter in inches.
|S||The next letter indicates speed rating.
This code applies to the tires maximum safe speed when
properly inflated and in good condition
|15||Wheel diameter in inches|
l 89H 89=89% of maximum load. The higher the I number, the more weight the tire can carry. Sidewall of tires is generally 2 plies tread Number of plies (layers) of material making up tire. 4 plies
Treadware 220 How long the tread should last. Not specific to a certain number of miles, but a tire rated 220 should last twice as long as a tire rated l 10.
Traction A How well the tire stops on wet roads in government tests. Best:A Worst:C
Temperature A How well the tire resists heat. Best:A Worst:C
DOT MAL9ABC056 Final digits of manufacturer's code tell when the tire was made; 056 on this example means 5th week of "96. Rubber hardens with age; look for recent date of manufacture.