Abstract :
Other than treadwear testing, tires are normally evaluated for important performance features in the virgin or new state. One performance feature that changes, as the lire wears in service, is wet traction. For any given tread compound the wet traction performance is jointly influenced by the groove void level (it changes with wear) and a factor that is a function of the aspect ratio, the "developed tread width." i.e., the actual width that contacts the road surface. Based on a comprehensive testing prograin, a wet traction performance parameter called the "specific discharge capacity" hah been developed. This accounts for the interactive or joint influence of both of these factors and how this influence changes across a range of operating conditions (speed, pavement texture). The specific discharge capacity is especially important at high levels of "criticality", i.e., deep water, slippery pavement, high speed.
