For tyres that are sold in the USA, they must carry the UTOG inscription. Defined by the USA Department of Transport, UTOG represents a grading performance in the areas of Treadwear, Traction and Temperature resistance. The grading system applies only to car tyres for diameters of 13" and above. Winter tyres are excluded.
A comparative rating based on wear rate when the tyre is tested in a controlled environment. A tyre graded 150 would wear 1.5 times more in D.O.T controlled conditions than a tyre rated 100. The relative performance of tyres, however, will depend on the actual conditions of use and may differ significantly from the grading.
Grades range from AA, A, Band C and represent the tyre's ability to brake in a straight-line test on net asphalt & concrete roads under controlled conditions. No considerations are made of the tyres ability to perform under acceleration, cornering, aquaplaning or peak traction conditions, which are all fundamental to a tyre's ability to have good net traction.
Grades range from A (highest) B and C and represent the tyre's resistance and ability to dissipate heat under controlled conditions. All tyres must meet the minimum requirements of grade C. Whatever temperature grade is assigned to the tyre, excessive speed, underinflation and excessive loads could all contribute to heat build-up and possible tyre failure.