Road-Load Performance Prediction Limitations by RRC Reduction

Abstract

This paper studied the vehicle running resistance prediction limitations based on tyre Rolling Resistance Coefficient (RRC) reduction. Tyre RRC reduction is one of the approaches used to increase fuel consumption efficiency of automobiles. It is known that the RRC value can vary with loading, velocity and temperature, and that the latter has the largest effect. Current tyre developments challenge the trade-off between maximum braking forcee coefficient (μ) and RRC, and present high thermal sensitivity of tyre tread rubber hysteresis loss property. Since different temperature conditions are ordered in ISO28580 tests which is used for Tyre RRC measurements and Road-Load tests which is used for vehicle running resistance measurements, the RRC is rendered less meaningful for estimations of running resistance than intended. The relation between RRC under Road-Load test conditions (RRC_RL) and under ISO test conditions (RRCiso) is investigated with the focus on temperature effect. It is found that the estimation of vehicle running resistance improvement by reducing RRCiso on the current tyre development processes is not representative enough of the improvement that can actually be obtained.