Ph.D. Walter H. Waddell
ExxonMobil Chemical Company, USA
Inflation pressure is a critical property for optimum tire and vehicle performance. Air pressure affects tire traction, cornering coefficient, tread wear and durability, and rolling resistance. Only when a tire is properly mounted and inflated to the vehicle manufacturer’s specification can it perform as designed to provide the driver with adequate traction and steering control, and optimum vehicle fuel economy.
Tire inflation pressure loss rate (IPLR) values have now been measured for over 300 passenger car tire models purchased worldwide. Rolling resistance force and calculated coefficient (RRC) have been measured for over 80 passenger car tire models. RRC has also been measured as a function of decreasing tire inflation pressure in order to calculate the change in vehicle fuel economy when the tire loses air. Using current and projected data for the number of light vehicles in China, the average distance these vehicles are driven and the average number of liters consumed to drive 100 kilometers, the potential fuel savings is calculated as a function of tire IPLR. Since pneumatic tires continuously lose air due to diffusion through the rubber, calculations are based on re-inflating the tire at 3-month intervals. Corresponding increases in CO2 emissions is estimated.