The Hidden Language of Tires (what the raised-rubber numerals and letters mean)
Example: 97S P215/70R15 M/S
- 97S - the "service description" contains the tire's load index (97), a code expressing the maximum weight that a tire can carry at its speed rating (S) - this combination means the tire is capable of carrying 1,609 pounds at its certified top speed of 112 mph - speed ratings range all the way up to ZR for speeds over 150 mph
- P - this prefix tells what kind of vehicle a tire fits - P stands for passenger cars, LT for light trucks, and T for temporary spare
- 215 - the tire's width in millimeters
- 70 - the "aspect ratio" - the tire's sidewall height as a percentage of its width - a low ratio means a shorter sidewall, which can improve steering response
- R - tire construction - R stands for radial (99.7% of the passenger tire market) - tires with other letters like B for belted bias and D for diagonal bias, usually go on low-speed vehicles like tractors
- 15 - the tire's rim diameter in inches (anywhere from 12 to 20 for today's street cars)
- M/S - mud and snow certification, signifying improved steering, stopping, and driving performance in foul weather
