Pneumatic tire

Abstract

A land ratio of a shoulder portion Sh of a tread portion is 57 to 72%, and a land ratio of a center portion Ce is 40 to 55%. In the center portion Ce, one row block made up of center blocks is formed. Each of the center blocks has its width gradually reduced from a position establishing an axial maximum width BW toward both a leading end and a trailing end relative to the tire rotating direction, each of the center blocks being provided with, at the leading end thereof, a tip portion that sharpens toward the leading end, and being provided with, at the trailing end thereof, a concave portion that smoothly concaves toward the leading end. In each of the center blocks, a ratio (BL/BW) between the axial maximum width BW and a maximum length BL in the circumferential direction is 1.00 to 1.20.

1 . A pneumatic tire, comprising:
 a tread portion having a tread pattern being formed by repetitive arrangement of substantially identically patterned pattern pitches in the circumferential direction of the tire, wherein   the tread portion has a center portion making up 50% of a tread ground-contact width whose center is a tire equator, and shoulder portions respectively situated on opposite sides of the center portion,   in each of the shoulder portions, shoulder main grooves extending inwardly from an outside relative to a tread ground-contact edge in the axial direction of the tire are arranged at certain intervals in the circumferential direction of the tire, whereby a shoulder land portion is established between the shoulder main grooves, a land ratio in each of the shoulder portion between the tread ground-contact edge and an outer edge of the center portion being 57 to 72%,   in the center portion, between the shoulder land portions being arranged on opposite sides in the axial direction of the tire, at least one center block row having center blocks arranged in the circumferential direction at certain intervals is provided, a land ratio of the center portion being 40 to 55%,   when the pattern pitches are each constituted of one of the shoulder main grooves and one of the shoulder land portions being adjacent to the one shoulder main groove, the pattern pitches each have a high land ratio region in which a sum of length in the axial direction of the tire of portions contacting the road surface on a tire axial line passing through the pattern pitch is 78 to 93% of the tread ground-contact width, and   the high land ratio region is continuous in the circumferential direction of the tire by 20 to 35% of a length in the circumferential direction of the tire of each of the pattern pitches.   
     
     
         2 . The pneumatic tire according to  claim 1 , wherein in the tread portion, the high land ratio region is arranged at 30 to 60 mm intervals in the circumferential direction of the tire. 
     
     
         3 . The pneumatic tire according to  claim 1 , wherein a maximum ground contact length in the axial direction of the tire of each of the shoulder land portions is more than 30% of the tread ground-contact width and no more than 40% of the tread ground-contact width. 
     
     
         4 . The pneumatic tire according to  claim 2 , wherein a maximum ground contact length in the axial direction of the tire of each of the shoulder land portions is more than 30% of the tread ground-contact width and no more than 40% of the tread ground-contact width.