| 摘要 |
PURPOSE:To increase a running ability on an ice and snow road and also prevent the damage of a tread shoulder part by making vertical fine ditches and sipings arranged along a tread edge to a ditch depth in a regulated range. CONSTITUTION:Plural vertical main ditches G are formed in a circumferential direction on a tyre tread surface 2 and a shoulder block SB formed between the vertical main ditches G which are symmetrical in the outer side and a tread edge is divided into inner/outer block pieces by the vertical fine ditch GB in a tread edge E side. The width WSB of an outer block piece SB1 is 0.06 times or more and 0.25 times or less of the tread half width WT. An edge siping ES is arranged on the block piece SB1 in the circumferential direction. The ratio between the average ditch depth BG of the vertical fine ditch and time vertical main ditch depth GH is 0.3 or more and 1.10 or less and the ratio between the average depth EH of the siping ES and the average depth BH of the vertical fine ditch is 0.25 or more and 1.25 or less. Thereby, a running ability on an ice and snow can be increased and the durability can be improved. |
