Temperature Grade Of Your Car Tires: What To Know And How To Interpret
In this third installment of the series of articles for our Tyre Guide regarding tire safety and performance parameters, we will be discussing temperature ratings of a tire. You can read the first article of the series about tire treadwear rating here, and the second article of the series about tire traction rating here.
As mentioned in previous articles, National Highway Traffic Safety Administration (NHTSA) in the United States came up with Uniform Tire Quality Grading (UTQG). The purpose of the grading was to provide consumers with useful information to help them purchase tires based on their relative treadwear ratings, traction ratings and temperature ratings. The grades are assigned by the tire manufacturers based on their test results or those conducted by an independent testing company they have hired.
The UTQG Temperature Grade specifies the extent to which heat is generated and/or dissipated by a tire during driving. Excessive heat, overtime, can hurt your tire rubber. The temperature grades, from highest to lowest, are A, B and C. More than a third of the tires achieve the highest grade of A, followed by 59 percent achieving a B grade, and about 11 percent get the lowest grade of C. It is widely recommended to go for a tire with a grade B or higher.
The grade is established by measuring a loaded tire’s ability to operate at high speeds without failure by running an inflated test tire against a large diameter high-speed laboratory test wheel.
Temperature Rating Speed (km/h)
B 160 – 185
C 135 – 160
On a tire, you can find the temperature grading at the sidewall, right after treadwear rating of the tire.
One very important point to keep in mind is that during testing, tires are kept in under controlled environment. The testers make sure that the tire is inflated properly and there is no excess load on the testing vehicle. If your tires are under-inflated, they will generate excessive heat. Other factors that can effect are your driving conditions, ambient temperature, road surface and vehicle load etc.