In 1976 tread wear was surveyed in 24 cities within the contiguous 48 states and in Fairbanks, Alaska. Each tire, exclusive of spares, was gaged for tread depth at two circumferential locations in three grooves: inner shoulder, center, and outer shoulder. The corresponding odometer reading was recorded. A national pattern of variation in tread life expectancy was revealed. Variation attributable to brand, size, vehicle, and wheel position was also found.