The Yokohama Rubber Co., Ltd.

Yousuke Sakamoto

Atsushi Tanno

Noboru Kuwahara

Isamu Kishizoe

A pair of main grooves disposed on both sides of a tire equator of a pneumatic tire and extending along a tire circumferential direction is configured so that a series of bent elements formed by connecting at least five linear groove portions via bend points are continuously and repeatedly arranged in the tire circumferential direction, and the at least five linear groove portions included in each of the bent elements have three or more types of inclination angles with respect to the tire circumferential direction and have five or more types of lengths.

Pneumatic tire

To provide a pneumatic tire that provides improved driving performance on unpaved roads and cut resistance. High blocks and low blocks with different raised heights are provided as side blocks provided in a side region. One of the high blocks and one of the low blocks adjacent to each other in a tire circumferential direction are defined as a block pair. The high block and the low block included in the block pair are partially in contact with each other. Thus, a side groove between these blocks is a closed groove. In each block pair, a pair of contour lines (a first linear portion, a second linear portion, and a third linear portion) define edges on both sides, in the tire circumferential direction, of a top surface of each of the high block and the low block.

A pneumatic tire includes a block group including shoulder blocks adjacent to each other with a shoulder lug groove therebetween and side blocks adjacent to each other with a side groove positioned on an extension of a shoulder lug groove between the shoulder blocks. Contour lines of side surfaces of the shoulder blocks on the outer side in the tire width direction and contour lines of the top surfaces of the side blocks extend on identical straight lines. Contour lines of the top surfaces of the side blocks, contour lines on a side away from the side groove between the side blocks, and contour lines of the narrow grooves formed on the side blocks each include straight portions extending along the tire radial direction on the side of the shoulder blocks and inclined portions extending in a converging manner toward the side groove between the side blocks.

A pneumatic tire includes shoulder lands and a center land, defined by main grooves on both sides of an equator in a zigzag pattern along a circumferential direction, are defined in a tread. Shoulder lug grooves extending in a width direction are formed in each of the shoulder lands. First and second center lug grooves, which extend from the shoulder lug grooves across each of the main grooves and are inclined at an angle of 45&#xb0;-70&#xb0; with respect to the width direction, are disposed in the center land. The first center lug groove terminates at the equator, and the second center lug groove terminates without reaching the equator. The first and second center lug grooves are alternately disposed in the circumferential direction. Connecting grooves inclined in an opposite direction to an inclination direction of the center lug grooves to connect the center lug grooves are formed in the center land.

In a pneumatic tire, a tread portion is provided with center blocks and shoulder blocks, and sidewall portions are each provided with side blocks. Surfaces of the blocks are provided with groove elements each including a narrow groove and/or a sipe. The first groove elements provided in the side blocks, the second groove elements provided in the shoulder blocks, and the third groove elements provided in the center blocks form a set of lateral groove group extending continuously from the side block on a first side to the side block on a second side in the tire lateral direction along the blocks across a main groove or an auxiliary groove.

Provided is a pneumatic tire. Center land portions between main grooves extending in a zigzag shape along a circumferential direction on both sides of an equator of a tread portion are defined into repeating units by first shallow grooves that extend along a lateral direction, have both ends communicating with portions other than bent portions of the main grooves, and are disposed at intervals in the circumferential direction. The repeating units are aggregates of four blocks defined by second shallow grooves extending from the main grooves in the lateral direction and converging toward one point on the equator, a third shallow groove extending from one of the first shallow grooves adjacent to the repeating unit to one of the second shallow grooves, and a fourth shallow groove extending from an other of the first shallow grooves adjacent to the repeating units to an other of the second shallow grooves.

A pneumatic tire of the present technology is a pneumatic tire provided with a tread portion, side wall portions and bead portions, a plurality of circumferential grooves extending in the tire circumferential direction being provided in the tread portion, and a belt-shaped sound-absorbing member being bonded via an adhesive layer to the tire inner surface in a region corresponding to the tread portion along the tire circumferential direction, wherein the width W of the sound-absorbing member is from 70% to 95% of the tire ground contact width TCW, and the total width of the circumferential grooves included in the region in the tire width direction in which the sound-absorbing member is disposed is from 25% to 40% of the width W of the sound-absorbing member.

The pneumatic tire of the present technology includes: a tread portion; sidewall portions; and bead portions. A pattern of grooves is formed on the tread portion, and a strip-shaped sound-absorbing member is bonded along the tire circumferential direction to a region of the tire inner surface corresponding to the tread portion via an adhesive layer. A first ground contact region is defined between the tire ground contact edge on one side in the tire width direction and the tire equatorial plane, and a second ground contact region is defined between the tire ground contact edge on the other side in the tire width direction and the tire equatorial plane. The sound-absorbing member is offset with respect to the tire width direction so that the centroid of a cross-section of the sound-absorbing member in a plane that includes a tire axis is located within the first ground contact region.

A pneumatic tire includes a tread portion; sidewall portions; bead portions; a carcass layer disposed extending between the pair of bead portions; a belt layer of a plurality of layers disposed on an outer circumferential side of the carcass layer in the tread portion; and a band-like noise absorbing member adhered to a region corresponding to a tire inner surface of the tread portion along the tire circumferential direction interposed by an adhesive layer. The pneumatic tire further includes a belt cover layer being disposed on an outer circumferential side of the belt layer across an entire width of the belt layer, the belt cover layer including organic fiber cords arranged in the tire circumferential direction; and a rate of change of a dynamic loaded radius when traveling at 270 km/h with respect to a dynamic loaded radius when traveling at 30 km/h being restricted to 2.0% or less.

A circumferential narrow groove of a pneumatic tire is disposed at a position that partitions an outer side second land portion and an outer side shoulder land portion. A center land portion is a rib that is continuous in a tire circumferential direction, and an inner side second land portion and the outer side second land portion are rows of blocks divided in the tire circumferential direction by pluralities of lug grooves. Additionally, a groove area ratio Sof the center land portion, a groove area ratio Sof the inner side second land portion, and a groove area ratio Sof the outer side second land portion have a relationship such that S&#x3c;S&#x3c;S. Moreover, a groove width Wd of the circumferential narrow groove and a maximum groove width Wmax of the other three circumferential main grooves to have a relationship such that 3.1&#x2266;Wmax/Wd&#x2266;5.0.

Growing community of inventors

Hiratsuka, Japan

Yousuke Sakamoto