Breaking it down
*Treadwear grade is used to determine how long a tire will last when compared to the government's control tire. For example, a control tire graded to 100 and a test tire are subjected to the same test at the track; if the test tire lasts twice as long as the control tire, it would carry a grade of 200.
*Traction performance
grade indicates how well the tire stops on wet asphalt and concrete, graded from highest to lowest as AA, A, B, and C. A tire with an AA grade will have a much shorter stopping distance than a C. Note that these grades don't indicate dry weather traction.
*Temperature resistance grades of A, B and C are used to show how well the tire dissipates heat generated by its contact with the road. This is especially important during aggressive or high-speed driving, since excessive heat buildup can lead to catastrophic failure.
*Load and speed ratings are typically located after the tire size and are often referred to as the 'service description.' The number corresponds to load, the letter to speed rating. For example, 91W translates as a tire at maximum inflation being able to support 1,356 pounds at 168 mph. It's an esoteric system.
Treadwear 300 Traction AA Temperature A