Tire Ratings - Treadwear
Treadwear grades are an indication of a tire's relative wear rate. The higher the treadwear number is, the longer it should take for the tread to wear down.
A control tire is assigned a grade of 100. Other tires are compared to the control tire. For example, a tire grade of 200 should wear twice as long as the control tire.
Of current tires:
15% are rated below 200
25% are rated 201 - 300
32% are rated 301 - 400
20% are rated 401 - 500
6% are rated 501 - 600
2% are rated above 600
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Tire Ratings - Traction
Traction grades are an indication of a tire's ability to stop on wet pavement. A higher graded tire should allow a car to stop on wet roads in a shorter distance than a tire with a lower grade. Traction is graded from highest to lowest as "AA", "A", "B", and "C".
Of current tires:
 3% are rated “AA”
  75% are rated “A”
    22% are rated “B”
    only 1 line of tires rated “C”
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Tire Ratings - Temperature

Temperature grades are an indication of a tire's resistance to heat. Sustained high temperature (for example, driving long distances in hot weather), can cause a tire to deteriorate, leading to blowouts and tread separation. From highest to lowest, a tire's resistance to heat is graded as “A”, “B”, or “C”.
Of current tires:
27% are rated “A”
59% are rated “B”
11% are rated “C”
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Q/ 99 mph     H/ 130 mph  R/  106 mph    V/   149 mph  S/  112 mph  W/  168 mph*
T/ 118 mph    Y/ 186 mph* U/ 124 mph