In this research, the influence of tire force and moment (F&M) characteristics on vehicle on-center steering performance was analyzed and then how to improve vehicle on-center performance was studied through controlling tire structure design parameter, tread pattern shape and tread grip characteristics.
First, the relationship between vehicle on-center steering performance and tire F&M characteristics was identified by comparing vehicle steering measurements and tire F&M measurements. It was found that key factor of tire related with on-center performance is aligning torque at lower slip angles. As the aligning torque at slip angle 1° increases, on-center feel is improved.
Second, the influence of tire design parameters on tire aligning torque was studied through F&M finite element (FE) analysis and measurement. It was found that the aligning torque at lower slip angle increases as stiffness of the tread and sidewall decreases. However, it shows trade-off with tire cornering force stiffness. It is necessary to optimize cornering force stiffness and aligning torque stiffness in tire structural design. In addition, as tread contact area to ground and viscosity of tread compound increase, both cornering force and aligning torque at lower slip angles increase together.
Finally on-center steering performance of an Europe mid-size wagon was improved by increasing tire aligning torque at lower slip angle based on these research results.
