Patent ID: 9132702
Filing Date: 2015-09-15
Classification: B60C,Y02T

Abstract:
1. A heavy duty pneumatic tire comprising a tread portion provided with a plurality of circumferentially and continuously extending main grooves that include a pair of shoulder main grooves disposed axially outermost side, and at least one center main groove disposed between the shoulder main grooves, the tread portion including a pair of middle portions each of which is between the shoulder main groove and the center main groove, each middle portion provided with a circumferentially and continuously extending middle sub groove, a plurality of axially outer middle lateral grooves extending from the middle sub groove to the shoulder main groove, and a plurality of axially inner middle lateral grooves extending from the middle sub groove toward the center main groove, the outer middle lateral grooves and the inner middle lateral grooves inclined at angle with respect to an axial direction of the tire with the same direction, the respective number of outer middle lateral grooves and the inner middle lateral grooves being in a range of from 40 to 50 in each middle portion, each of the outer middle lateral grooves and the inner middle lateral grooves including a shallow bottom part having a depth smaller than that of the shoulder main grooves and the center main groove, the shallow bottom part provided with a groove bottom sipe extending along a longitudinal direction of each lateral groove, and the groove bottom sipe including a first portion and a second portion, the first portion having a depth from a top surface of the middle portion to its bottom in a range of from 0.85 to 1.0 times in relation to a depth of the center main groove, the second portion having a depth from a top surface of the shallow bottom part to its bottom in a range of from 0.30 to 0.70 times in relation to a depth from a top surface of the shallow bottom part to a bottom of the first portion.