How to Read the Speed Rating on Tires

The speed rating indicates that maximum speed for safe driving on a tire.

Tire manufacturers rate all tires to be safe to a certain speed. The speed rating is the maximum speed at which a car running on that tire should be driven. Speed ratings are provided through a letter code printed on the sidewall of the tire. The tire with the most famous speed rating, the Z-rated tire, is no longer in common use. The Z-rating indicated that the tire could be driven in excess of 149 mph but did not have a top speed limit.

Instructions

1. Locate the code indicating the load range and speed rating on the side of the tire. The two ratings form a three or four digit group placed after the size on the tire, such as "93T" or "89H".

2. Write down or note the letter part of the load and speed rating. Tire speed ratings use only letters. Passenger tire speed ratings use the letters Q through W plus H.

3. Look up the speed rating for the letter from the tire. Here are the maximum speeds in miles per hour for some of the most common ratings:

   S: 112 mph.

   T: 118 mph

   H: 130 mph

   V: 149 mph

   A more complete chart from Dunlop Tires is linked in the Resources section of this article.

Tips & Warnings

• The Z rating has been replaced by W and Y indicating maximum safe speeds of 168 mph and 186 mph respectively. The Z may still be used in the tire size, showing ZR instead of the R for radial.

• The tire speed ratings originated in Germany and are listed in 10 kilometer-per-hour increments. This is why the ratings are somewhat oddly numbered in miles per hour.

References

• NHTSA: Tire Safety
• Tire Rack: How to Read Speed Rating, Load Index & Service Descriptions

Resources

• Dunlop Tires: Speed Ratings