Rolling Resistance Evaluation of Winter Tires on In-Service Road Surfaces

Rolling resistance, the energy dissipated due to the rolling movement of a pneumatic tire over a surface, is a relevant factor that should be considered when aiming at a more energy efficient road infrastructure as well as for reducing CO2 emissions. The energy dissipation, as a result mainly of hysteretic losses, is dependent on the tire, the road surface, and the operating temperature, among other factors. In this study, 50 different tires of five different types—all-season tires, summer tires, winter tires without studs, winter tires with studs, and winter tires with hard particles—were evaluated with respect to rolling resistance on two different road surfaces, at three different test speeds and different states of tire wear. In addition to the full-scale field tests, a drum facility was used to evaluate rolling resistance of the same tires in a more controlled environment. This resulted in more than 500 measurements that were analyzed in this paper. Previously, no data regarding rolling resistance of studded winter tires had been published, and there have been very few studies comparing measurements on drums with measurements on road pavements. In the field, rolling resistance was significantly depending on tire type, and many tested tires performed differently on the two surfaces. No significant correlation was found between labeled tire values and rolling resistance measured on roads, or between rolling resistance measured on roads and on a drum facility. Better correlations were found between labeled tire values and our own drum results. This calls for a review of the relevance of the energy labeling procedure.