cross shape the center blocks 11 improve effectively the traction performance of the tire a width w 1 of the first portion 18 in the circumferential direction of the tire is preferably 0 10 times or more more preferably 0 15 times or more and preferably 0 30 times or less more preferably 0 25 times or less longer than the space l 1 this allows the blocks 10 to bite effectively into the road surface thereby achieving further improved grip each of the shoulder blocks 12 includes end edges 12 e and 12 e extending in the circumferential direction of the tire and is formed in an almost trapezoidal shape for example the circumferential length w 2 of the shoulder blocks 12 increases gradually outward in the axial direction of the tire the shoulder blocks 12 improve the stable driving performance during cornering each of the middle blocks 13 includes end edges 13 e and 13 e extending in the circumferential direction of the tire and is formed in an almost trapezoidal shape each of the middle blocks 13 includes an inner portion 13 a and an outer portion 13 b a width w 3 of the inner portion 13 a is kept constant a width w 3 of the outer portion 13 b increases gradually outward in the axial direction of the tire the land sea ratio of the tire 1 in the embodiment is 10 to.