| CPC B60C 9/08 (2013.01) [B60C 11/1236 (2013.01); B60C 9/2006 (2013.01); B60C 2011/0341 (2013.01); B60C 2200/06 (2013.01)] | 17 Claims |
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1. A pneumatic tire for heavy duty having an aspect ratio of 65% or less comprising:
a tread portion;
a pair of bead portions;
a carcass extending from one of the bead portions to the other one of the bead portions via the tread portion; and
a belt layer arranged inside the tread portion,
wherein
the tread portion includes a plurality of circumferential grooves extending continuously in a tire circumferential direction,
the circumferential grooves include a pair of shoulder circumferential grooves and at least one crown circumferential groove arranged between the shoulder circumferential grooves,
the crown circumferential groove is a narrow groove that closes when contacting the ground under a condition of being loaded with a maximum tire load,
each of the shoulder circumferential grooves is a wide groove that does not close when contacting the ground under the condition of being loaded with the maximum tire load,
the belt layer includes a plurality of belt cords made of metal and arranged obliquely with respect to the tire circumferential direction,
a pair of outer ends in a tire axial direction of the belt layer are each positioned axially outside a respective one of the shoulder circumferential grooves,
a belt half width from a tire equator to one of the outer ends of the belt layer is 55% or more and 85% or less of a carcass half width, the carcass half width being a distance in the tire axial direction from the tire equator to the carcass at a maximum tire width position in an axial half of the tire,
wherein the belt layer incudes a plurality of belt plies overlaid in a tire radial direction,
in each of the belt plies, the belt cords are arranged obliquely to the same side with respect to the tire circumferential direction,
at least one pair of the belt plies adjacent to each other in the tire radial direction are overlaid so that the belt cords of one of the belt plies of the pair intersect with the belt cords of the other one of the belt plies of the pair,
wherein each of the shoulder circumferential grooves and the or each crown circumferential groove extend in a zigzag manner,
a minimum distance (L3) in the tire axial direction between one of the shoulder circumferential grooves and the crown circumferential groove or one of the crown circumferential grooves adjacent thereto is larger than a maximum distance (L4) between adjacent outer ends of the belt plies included in the belt layer,
wherein an amplitude in the tire axial direction of a groove center line of the or each zigzag shaped crown circumferential groove in the tread plan view is smaller than a distance (d1) in the tire radial direction from the bottom of the or each crown circumferential groove to the belt layer,
wherein an amplitude in the tire axial direction of a groove center line of each of the zigzag shaped shoulder circumferential grooves in the tread plan view is larger than a distance (d2) in the tire radial direction from the bottom of each of the shoulder circumferential grooves to the belt layer, and
in a pair of the or each crown circumferential groove and one of the shoulder circumferential grooves adjacent thereto, zigzag phases of the or each crown circumferential groove and the one of the shoulder circumferential grooves are opposite to each other.
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