| 摘要 |
PURPOSE:To mainly improve the wear resistance of a tread by applying the constitution wherein a particular perpendicular from a lug groove laid on the crown part of the tread specifies the value of a crown part for arc length, and the negative ratio of the lug groove for the total area of the crown part. CONSTITUTION:From each point of a lug groove center line 24 equally dividing a lug groove 16 in a tire peripheral direction at one side of a crown part center line 22 in the tread of a tire 10 in a tire widthwise direction, a group 28 of perpendiculars are so extended to a meridian 26 arbitrarily taken on the surface of a crown part so as not to cross the group 28. In the case, a difference D between the maximum length D1 and minimum length D2 of the perpendiculars is so established as to satisfy a relationship of 0.08<=D<=0.12C for the arc length of a crown part 15. Also, the lug groove center line 24 is angled at one side of the crown part center line 22, and the total area AN of the crown part 15 and the negative area AN occupied by the lug groove 16 are so determined as to satisfy a relationship of 0.21<=AN/AT<=0.28. |
