Effect of Ambient and Tyre Temperature on Truck Tyre Rolling Resistance

Rolling resistance is consuming a large portion of the generated powertrain torque and thus have a substantial effect on truck energy consumption and greenhouse gas emissions. EU labelling of tyres mandates the manufacturers to measure rolling resistance at +25 degrees C ambient temperature after stabilised rolling resistance has been established. This is a convenient way of comparing rolling resistance but disregards aspects such as transient rolling resistance and influence of the ambient temperature. For many purposes, such as dimensioning batteries for electric vehicles, this value is not representative enough to give a good understanding of the rolling resistance. In this article, the rolling resistance of a truck tyre was measured at different ambient temperatures (-30 to +25 degrees C) in a climate wind tunnel and a considerable tyre and ambient temperature dependency on rolling resistance was found. The investigation shows that the temperature inside the tyre shoulder has a good correlation with rolling resistance. Measurements with spraying water on tyres were conducted showing a considerable increase in rolling resistance due to higher cooling effect. Driving range simulations of a long haulage battery-electric truck have been conducted with temperature-dependent rolling and aerodynamic resistance, showing a significant decrease in driving range at decreasing temperature.