| 摘要 |
PURPOSE:To reduce the generation of noise by specifying the width of a center part, the number of pitches, and the angle of the lug groove of each of a center part and a shoulder part, in a tire formed such that a forced rise amount of a tread part along with the increase of a running speed is increased at a center part. CONSTITUTION:A tire is formed such that a forced rise amount of a tread part along with the increase of a running speed is increased at a center part than at a shoulder part. In this case, a width A of the center part to an earthing width B of a tread is set to a relation of 0.40<=A/B<=0.75. The number N of pitches of a lug groove 6 of the center part, the number Nb of pitches of a lug groove 7 of the shoulder part, an average angle thetaa of the lug groove 6 with the meridian of the center part, and an average angle thetab of the lug groove 7 with the meridian of the shoulder part are set so as to satisfy conditions of 30<=Na<=50, 60<=Nb<=80, 1.2<=Nb/Na<=2.0, 30 deg.<=thetaa<=55 deg., and 0 deg.<=thetab<=30, respectively. |
