Tyre ratings can be found on NHTSA's web site at www.safercar.gov. Here consumers can view ratings for more than 2,200 lines of tyres. Under federal regulation, ratings also must be moulded into the outer sidewall of all passenger tyres.
NHTSA rates the quality of tyres with letter or number grades in three categories: temperature (heat resistance), traction and tread wear.
Temperature (heat resistance) is graded "A" (highest); "B," or "C" (lowest). A "C" grade represents the minimum performance standard required by federal regulation. Currently, 27% of tyres are rated "A," 59% are rated "B" and 14% are rated "C."
Traction also is rated with letter grades, based on wet road stopping distances, and graded "AA" (highest), "A," "B" or "C" (lowest). Currently, 3% of tyres are rated "AA;" 75% are "A;" and 22% are "B." Only one line of tyres is rated "C."
In grading for tread wear, a control tyre is assigned a grade of 100. A tyre with a grade of 200 can be expected to last twice as long as the control tyre, while one with a grade of 80 is normally less durable. Currently, the highest reported tread wear rating is 700; while 98% of tyres rank 600 or below, 92% rank 500 or below; 72% rank 400 or below; 40% rank 300 or below; and 15% rank 200 or below.
No comparable tyre quality ratings are yet available in Europe.