| 摘要 |
PURPOSE:To enhance friction force especially against icy and snowy roads by forming main grooves and transverse grooves on the surface of a tread and respectively specifying the width of the transverse grooves, a groove area ratio and snow traction noise, as well as forming the tread part with specified foam rubber having closed cells. CONSTITUTION:In the tread surface 10, multiple main grooves 1 (1-1 to 1-3) extend to the direction of tire circumference E-E' and multiple transverse grooves 2 that mutually connect with respective main grooves 1 are respectively formed. And, respective settings of the width of respective transverse grooves 2 below 5mm, the groove area ratio of the surface 10 at 25%-40%, and snow traction index (STI) at 180-250 are performed. On the other hand, the tread part is formed with foam rubber having closed cells. Also, the foam rubber is formed blending an urea light auxiliary agent less than the same quantity against the blending quantity of a foaming agent, and respective settings at 0 deg.C of JIS hardness at 60-70, the average bubble area at 500-600mum<2>, the variation coefficient of respective bubble area at 0.5-0.8, and the bubble occupation area ratio at 10%-40% are performed. |
