Temperature grade (A, B, C)
A grade of how well the tire resists building up heat, and gets rid of it, on a laboratory test wheel, from A (highest) through B to C.
Easily confused with
How to read it
The temperature grade is one of the Uniform Tire Quality Grading Standards grades (49 CFR 575.104): the word TEMPERATURE followed by A, B or C. The regulation’s explanation says the grades represent the tire’s resistance to the generation of heat and its ability to dissipate heat, tested on an indoor laboratory test wheel. The wheel runs at 375 rpm and then 25 rpm faster every 30 minutes, up to 30 minutes at 575 rpm. A tire that fails to complete the 500 rpm stage is graded C; B needs the 500 rpm stage completed, and A the 575 rpm stage. Grade C is the level every passenger car tire must meet under Federal Motor Vehicle Safety Standard No. 109; B and A are above that minimum.
Also searched as: temperature rating, UTQG temperature.
What each marking means under the standard that defines it. This page describes markings; it doesn’t advise on choosing, fitting, inflating or replacing tires.
What the grade assumes
The regulation says the grade is established for a tire that is properly inflated and not overloaded, and that excessive speed, underinflation or excessive loading, separately or together, can cause heat buildup and possible tire failure. NHTSA’s tire page gives driving long distances in hot weather as an example of sustained high temperature, which it says can make a tire deteriorate. Hankook’s guide puts the floor plainly: any tire rated below C is considered unacceptable.
How grades are spread
NHTSA’s tire page gives the spread across current tires: 62% are rated A, 34% B and 4% C.
Temperature grade or speed rating?
The speed rating in the service description is a separate marking. USTMA describes it as a speed capability in standardized laboratory tests that relate to highway speeds; the temperature grade is a comparison on a test wheel, graded A to C.
More tire sidewall markings
Browse symbols drawn with curves and waves or letters and numbers.
Sources
- 49 CFR 575.104: Uniform tire quality grading standards, 49 CFR 575.104, Office of the Federal Register, eCFR (NHTSA regulation), 575.104(d)(2)(iii), (g)(9), Figure 2
- Tires, National Highway Traffic Safety Administration (NHTSA), How are tires rated? Temperature
- Tire Care and Safety Guide, U.S. Tire Manufacturers Association (USTMA), pp. 8-9
- Tire Sidewall: Tire Guide, Hankook Tire America, UTQG, Temperature
Last reviewed September 29, 2026 by Rory Hansen. How we research