"The tire also has a B rating for wet traction and a B rating for tread wear."
Tread wear is assigned a number, actually. The Uniform Tire Quality Grade (UTQG) standards are set up like this: Treadwear, Wet braking traction, Temparature resistance. For example, the current tires on my Aspire are 420 A A.
Tire Tech Information - Uniform Tire Quality Grade (UTQG) Standards