| 摘要 |
PURPOSE: To reduce the irregular abrasion generated on a block type tread by applying a larger tilt angle divergently toward the groove bottom against the normal line erected at the block end edge to the side wall of a narrow-width block among blocks than to the side wall of a wide-width block. CONSTITUTION: A side wall 5 facing a lug groove 3 of a narrow-width block 41 is inclined divergently toward the bottom 7 of the lug groove 3 at the angleαagainst the normal line (n) erected at the block end edge, a side wall 6 facing the lug groove 3 of a wide-width block 42 is likewise inclined toward the bottom 7 of the lug groove 3 at the angleβagainst the normal line (n), and the relation between them is set toα>β. For the narrow-width block 41 and the wide-width block 42 arranged on both sides of a shoulder main groove 22 , the side wall 5 of the former is inclined divergently toward the bottom 8 of the shoulder main groove 22 at the angle ofγagainst the normal line (n), the side wall 6 of the latter is inclined toward the bottom 8 of the shoulder main groove 22 at the angleδagainst the normal line (n), and the relation between them is set toγ>δ. |
