This report examines the current and expected future trends in highway tire design and their effects on vehicle rolling resistance and fuel economy. The primary emphasis is on passenger cars, operated under conditions typified by the US Environmental Protection Agency Urban, Highway, and Combined Cycles, and heavy duty trucks operated over the road. Analytical and experimental data indicate rolling resistance-fuel economy sensitivity factors of 0.2 for passenger cars over the Combined Cycle, and 0.4 for a fully loaded tractor-van trailer at 55 mph. Improved radial construction, low hysteresis materials, and higher inflation pressures are the primary mechanisms through which passenger car tire rolling resistance has been reduced. Further design refinements are expected in the near future to achieve reduced rolling resistance and optimal ride and handling qualities at acceptable production cost. Similarly, heavy duty truck tire designs have been improved through the use of radial construction, and further rolling resistance reduction is expected through design modifications such as lower aspect ratio. (ERA citation 11:034208)
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