Patent ID: 9731555
Date: 2017-08-15
CPC Classifications: B60C

Claim:
1. A pneumatic tire comprising a tread portion having a pair of tread edges, the tread portion being provided with a pair of circumferentially and continuously extending zigzag shoulder main grooves adjacent to each tread edge and a pair of circumferentially and continuously extending zigzag crown main grooves disposed between the shoulder main grooves to define a pair of middle portions each of which is between the adjacent shoulder main groove and crown main groove, the respective middle portions being provided with a plurality of inner middle lug grooves and a plurality of outer middle lug grooves, each outer middle lug groove extending from the shoulder main groove to its axially inner end terminating within the middle portion while decreasing its groove width toward the axially inner end, each outer middle lug groove being inclined in a same direction with respect to an axial direction of the tire, the outer middle lug grooves arranged in the circumferential direction of the tire with alternately arranged first pitches and second pitches, wherein the second pitches are larger than the first pitches, and each inner middle lug groove extending from the crown main groove to its axially outer end terminating within the middle portion while decreasing its groove width toward the axially outer end, the inner middle lug grooves arranged in the circumferential direction of the tire with substantially the same pitches, each inner middle lug groove including a pair of groove edges which are inclined in a same direction with respect to the axial direction of the tire, wherein the inner middle lug grooves comprise a first inner middle lug groove having a first angle with respect to the axial direction of the tire and a second inner middle lug groove having a second angle larger than the first angle with respect to the axial direction of the tire, and wherein the first inner middle lug groove and the second inner middle lug groove are alternately arranged in the circumferential direction of the tire.