Road-Surface Influence on Tire Rolling Resistance

A unique “quarter-car” trailer has been designed and built at the Belgian Road Research Center for measuring the rolling resistance of a reference tire on the road. Its design and performances are briefly outlined. It has been used for investigating the influence of road-surface characteristics on the rolling drag experienced by a car tire. On a wide variety of surface types and conditions on dry paved roads, the coefficient of rolling resistance ranges between 0.013 and 0.021. In terms of fuel consumption, this can be converted into 9% relative influence of the road surface. With respect to the intrinsic tire rolling resistance coefficient (0.010) as measured on a particularly smooth and even test track, the worst road surface can double the rolling resistance. The main surface-related influencing factor has been found to be surface profile irregularities in a wavelength range lying between macrotexture and un-evenness, namely megatexture (50 mm < wavelengths < 500 mm), which had already been reported as responsible for tire/road noise.