Abstract
Tires play an important role in vehicle dynamics, as they are the only physical connection between the vehicle and the road surface. Reduction of tire rolling resistance, i.e. increase of tire energy efficiency, in general causes deterioration of tire handling characteristics, such as cornering stiffness and relaxation length as well as tire grip. On full vehicle scale, such ‘eco’ tires usually lead to compromised vehicle agility, responsiveness and driving safety. Therefore, in this paper efficient solutions for compensation of disadvantageous characteristics of ‘eco’ tires are investigated, without leaving the scope of the wheel subsystem. To this extent, extensive research tire measurements regarding handling and rolling resistance characteristics have been carried out. These measurements focus on investigation of the influence of rim width and internal pressure on tire behavior. In particular, cornering stiffness and relaxation length as well as rolling resistance are measured. First, in this research an exemplary ‘eco’ tire of the ‘tall and narrow’ type is evaluated regarding its general characteristics in comparison with a regular reference tire. Then, in order to derive general relationships between rim width and tire characteristics, influence of rim width is investigated for regular tires. This knowledge is subsequently used in investigation of the influence of rim width on a sample ‘eco’ tire, which is combined with analysis of internal pressure. On the basis of these analyses a combination of these two influencing factors is derived based on their singular influence and measurements for comparison of expected and actual results are carried out. Finally, conclusions on measures for counteracting handling deficits of ‘eco’ tires are derived and recommendations are formulated.
KEYWORDS – Eco tires, vehicle dynamics, vehicle handling, tire characteristics, rolling resistance