Tire Speed Ratings

For hundreds of years, a tire was a simple band of iron wrapped around a wooden spoked wheel. A driver could have serious problems with this arrangement if they hit a rock at 10 miles an hour, and because many did, blacksmiths and wheelwrights enjoyed thriving businesses. After the automobile introduced the public to much higher speeds, tire technology was forced to improve, and the extent to which it did is quite remarkable. As a result of new rubber formulations, advances in tread design, and many structural innovations, today’s tires are able to handle significant loads and are engineered to survive speeds which are many times greater than 10 miles an hour. In fact, tires are now engineered for a range of speeds, and marked with letter codes to indicate their speed ratings. While these vary depending on the specific tire; in general, the code molded into the side of a tire will be arranged like this: P205/75R15 97S, and the letter at the end (in this case, an ‘S’) represents the tire’s speed rating. Because it is very important to know and understand the speed rating for your tires, we’ve listed these for miles per hour (mph) in the table below. Note: in order for these speed ratings to apply, the tire load rating must not be exceeded.