| 摘要 |
PURPOSE: To reduce the wear of ground-contacting shoulder areas by providing pressure distribution grooves in the shoulder areas, providing a central ground- contacting area with a predetermined axial width, and using rubber compounds with predetermined characteristics for the areas. CONSTITUTION: A tread 22 has ground-contacting shoulder areas 30, 32 on both sides of a central ground-contacting area 34 having an axial width which is 82 to 96% of the tread width, and pressure distribution grooves 44, 46 are formed on a circumference around this ground-contacting portion. The second rubber compound of the ground-contacting shoulder areas 30, 32 has a tear strength value of at least 140 kNm<-1> as measured by ASTM D624 Die 'B', which is higher than the tear strength value of the third rubber compound of the central ground-contacting area. The third rubber compound of the central area has a Healy Rebound value of at least 74 percent as measured by ASTM D1054 at 100 deg.C, which is higher than the Healy Rebound value of the second rubber compound. The wear of the shoulder areas can thus be reduced. |
