Pneumatic tire

Abstract

To enhance uneven wear resistance with achieving higher levels of dry grip performance and wet performance, a tread surface 2 is provided with one circumferential main groove 3 in an outer region 2 o thereof directed outward of a vehicle and with first and second circumferential main grooves 4 and 5 in an inner region 2 i thereof directed inward of the vehicle, a central region Rc between the circumferential main grooves 3 and 4 is formed into a rib 10 extending continuously in the circumferential direction, an outer shoulder region Ro between the circumferential main groove 3 and TEo is formed into a row of outer blocks 12 defined by inclined main grooves 6 , and the outer blocks 12 are provided with inclined sub-grooves 13 having an inclination direction different from that of the inclined main grooves 6 , thereby dividing each of the outer blocks 12 into a first block portion 12 A on a tire equator side and a second block portion 12 B on a ground contact edge side.

What is claimed is: 
     
         1 . A pneumatic tire having three circumferential main grooves disposed asymmetrically with respect to a tire equator, said pneumatic tire having a tread surface divided by the tire equator to an outer region, meaning at the vehicle outer side when the tire is mounted on the vehicle, and an inner region, meaning at the vehicle inner side when the tire is mounted on the vehicle, and having one single outer region circumferential main groove disposed in said outer region and extending in a circumferential direction of the tire, and first and second inner region circumferential main grooves disposed in said inner region, said first inner region circumferential main groove extending in the circumferential direction on a tire equator side and said second inner region circumferential main groove extending in the circumferential direction on a ground contact edge side, wherein:
 a central region between said outer region circumferential main groove and said first inner region circumferential main groove is formed into a rib extending continuously in the circumferential direction,   an outer shoulder region between said outer region circumferential main groove and an outer region ground contact edge is provided with outer inclined main grooves each extending at a slant with respect to the circumferential direction and crossing said outer shoulder region, thereby forming said outer shoulder region as a row of outer blocks disposed at intervals in the circumferential direction,   each of said outer blocks is provided with an inclined sub-groove having an inclination direction different from that of said outer inclined main grooves with respect to the circumferential direction and extending between adjacent said outer inclined main grooves, thereby dividing each of said outer blocks into a first block portion on a tire equator side and a second block portion on a ground contact edge side,   said outer region circumferential main groove comprises
 a groove bottom portion extending in the circumferential direction in the form of a wave, 
 lower groove wall portions rising up from both side edges of said groove bottom, and 
 upper groove wall portions extending from upper edges of said lower groove wall portions to the tread surface, and 
   intersection portions at which said upper groove wall portions intersect with the tread surface, extend straight in the circumferential direction.   
     
     
         2 . The pneumatic tire of  claim 1 , wherein
 inclination angle θi of said upper groove wall portions with respect to a normal line to the tread surface is constant over the full circumferential length, so that the height of the intersection position at which said upper groove wall portions intersect with said lower groove wall portions is changed in the circumferential direction.