Passenger tyres are usually graded based on three factors: tread wear, traction and temperature resistance.
Uniform Tyre Quality Grading System (UTQG)
Except for snow tyres, US federal authorities require manufacturers to grade passenger car tyres based on three factors: tread wear, traction, and temperature resistance.
This grade measures the wear rate of the tyre when tested under controlled conditions. 100 is taken to represent a basic quality standard. A tyre graded 200 would wear twice as long on the test track as one graded 100. More Than 100 – Better, 100 – Baseline, less Than 100 – Poorer. Note: tread wear grades are valid only for comparisons within a manufacturer's product line. They are not valid for comparisons between manufacturers.
Traction grades represent the tyre's ability to stop on wet roads. The grade is based upon "straight ahead" braking tests. It does not indicate cornering ability. A – best, B – intermediate, C – acceptable
The temperature grades represent the tyre's resistance to the generation of heat. A – best, B – intermediate, C – acceptable. Note: federal law requires that all tyres meet at least the minimal requirements of grade C.