I. Introduction
Tire/road noise is generated by several sub-sources, such as tread vibration, air pumping, slip-stick, adhesion et al. [1]. Therefore tread pattern noise is the main noise, which is the important link of low noise tire design. The common design method usually cannot guarantee low noise tire. We must optimize tire thread pattern in order to scatter the frequency of the pattern noise to reduce noise level [2]–[3].