How to Buy Tires Based on Speed Ratings

Before being put on the market, all tires are tested to find out how fast they can safely carry your car. Speed ratings are recorded in letters, and if you know how to decipher the letters you can easily choose a tire that is safely rated for your car and the speed that you drive it.

Difficulty:

Easy

Instructions

1. Check the speed ratings only on tires that are manufactured in a size to fit your car. Be aware that trucks, SUVs, sedans and sports cars may use different types of tires.

2. Locate a letter in the tire's service descriptions, which is a series of numbers and letters, that comes at the very end of the series for tires designed for cars produced after 1991.

3. Find a letter earlier in the series of numbers for cars produced before 1991. The letter indicated the speed rating should be the first of only two letters.

4. Look up the exact speed that corresponds to each letter. Each letter indicates a top speed for that tire, which goes up as the letters proceed in the alphabet. "Q" is the threshold for 100 mph top speeds.

5. Understand the difference between "Z" ratings and ratings above "V." "Z" was initially thought to be the highest speed of tire (149 mph and up), but "V" (top speed of 149), "W" (top speed of 169) and "Y" (top speed of 186) were introduced later.