Prior research1 has suggested the need for an increase in minimum legal passenger car tire tread depth requirements. One of the objections raised to this suggestion is that no data are available to show how important tread depth is in vehicular loss of control. To address this concern, more than 7,000 accident reports have been analyzed. Accident situations that indicate a loss of wet-road traction have been studied in detail. The resulting analysis allows estimates to be made of tread-depth-related deaths and injuries in the U.S.