What Is a Tire Q Rating?by Charles Green
Every tire is speed rated, which means that you can safely travel at a certain speed limit without worry that your tires will fail you. Tires are assigned a letter rating representing the top speed you can drive.
Review the ratings. Nine separate letter ratings are assigned to passenger vehicle tires with Q the lowest and Y or Z the highest. Each letter stands for the top speed you can drive under ideal road conditions.
Understand the Q rating. Q is the lowest rating, but with a maximum speed of 99 mph, you should safely be able to put these tires on your car. Certain western states have a posted speed limit of 75 mph, thus you are well within the range of these tires.
Find the speed rating. On the sidewall of your tires, you can find a series of numbers and letters. Immediately following your tire's size, which will look something like P215/65R15, you'll see an alphanumeric combination such as 89H. The numbers represent vehicle load factor, and the letter is the speed rating.
- photo_camera Thinkstock/Comstock/Getty Images