Patent ID: 9561688
Date: 2017-02-07
CPC Classifications: B60C

Claim:
1. A pneumatic tire comprising a tread portion provided on each side of the tire equator with a crown main groove and a shoulder main groove extending continuously in the tire circumferential direction, so that the tread portion is axially divided into a center land zone between the crown main grooves, a pair of middle land zones between the crown main grooves and the shoulder main grooves, and a pair of shoulder land zones axially outside the shoulder main grooves, wherein the middle land zones are each provided with a plurality of middle auxiliary grooves extending axially inwardly from the shoulder main groove and terminating within the middle land zone, the shoulder land zones are each provided with a plurality of shoulder axial grooves extending axially outwardly from the shoulder main groove, the width of the shoulder axial groove measured at the axially outer end is larger than the width of the shoulder axial groove measured at the axially inner end, and the axially inner ends of the shoulder axial grooves are respectively overlapped with the axially outer ends of the middle auxiliary grooves at least partially in the tire circumferential direction, wherein each of the shoulder axial grooves comprises a first portion extending axially outwardly from the shoulder main groove and having a constant groove width, a second portion extending axially outwardly from the first portion and having a constant groove width more than the groove width of the first portion, and a third portion extending axially outwardly from the second portion to the tread edge and having a groove width more than the groove width of the second portion, wherein the second portions extend substantially parallel with the tire axial direction, and the first portions extend straight at an inclination angle of not less than 5 degrees and not more than 25 degrees with respect to the tire axial direction, wherein the shoulder land zones each have a constant axial width, the first portions have an axial length of not less than 0.40 times the axial width of the shoulder land zone, the second portions have an axial length of not less than 0.32 times the axial width of the shoulder land zone, the first portions have a depth, and the second portions have a depth more than the depth of the first portions.