An Approach for Evaluating Rolling Resistance in Kart Racing Tires

Drivetrain electrification is increasing in the kart racing sector since noise emissions are an important factor in urban areas. To improve range, it has become necessary to optimize the rolling resistance of kart racing tires. This paper introduces a parameter study for small bias-ply tires which are used in kart racing and investigates the effect of these parameters on rolling resistance. In recent literature, rolling resistance is mostly examined in radial passenger car tires. Most testing devices are limited to rim sizes from ten inches upwards. In this study, a test rig was developed with focus on low cost and small rim sizes. This self-developed test rig was validated through a comparison with an approved test rig according to ISO 18164 standard. A parameter study was conducted to investigate the effect of changes in the construction of the tire. These changes affect the warp count of the carcass fabric and the crown angle of the different plies. These parameters were varied in three steps. The rolling resistance was measured by performing coast down tests with internal air pressure kept constant. The velocity range for the measurements was defined by the velocities driven on a kart race track. The investigation of carcass parameters provides better insight into the rolling resistance of small bias-ply tires and delivers systematic results to optimize the tire construction with respect to rolling resistance in tire design. In addition, procedures applicable for rolling resistance measurements of tires smaller than 10 inch rim size are presented in this article.