Bridgestone Corporation

Oki Electric Industry Co., Ltd.

Akiyoshi Shimizu

Akira Nakamizo

Hiroshi Kobayashi

Kohshi Katoh

Hiroshi Mouri

Naohiro Sasaka

Naoto Yamagishi

Tetsunori Haraguchi

Hiroyuki Matsumoto

Kazuo Uchida

Ken Masaoka

Nagakazu Kuwahara

Chishiro Tanabe

Susumu Yamada

Kazuho Kawaguchi

A pneumatic tire includes, on a tread surface, circumferential main grooves extending in the tread circumferential direction, and land portions defined between circumferential main grooves adjacent in a tread width direction among the circumferential main grooves or by the circumferential main grooves and tread edges. The land portions include widthwise sipes (or grooves) extending in the tread width direction, and each widthwise sipe (or groove) includes a tread surface side sipe (or groove) portion extending from the tread surface inward in a tire radial direction, a first branched sipe (or groove) portion branching and extending from the tread surface side sipe (or groove) portion inward in the tire radial direction, and second branched sipe (or groove) portions branching and extending from respective tire radial inner ends of the first branched sipe (or groove) portion inward in the tire radial direction.

Pneumatic tire

A pneumatic tire of the present disclosure includes, on a tread surface, a plurality of circumferential main grooves extending in the tire circumferential direction, and a plurality of land portions defined between circumferential main grooves adjacent in the tire width direction among the plurality of circumferential main grooves or by the circumferential main grooves and tread edges. The land portions include at least one circumferential sipe extending in the tire circumferential direction. The circumferential sipe includes a plurality of widened portions arranged in the tire circumferential direction. In a reference state, each widened portion is formed only from a portion that, from one side towards the other side in the tire circumferential direction, extends from the tread surface inward in the tire radial direction.

A pneumatic tire includes, in a land portion, at least one circumferential sipe extending in the tire circumferential direction. At a first position, from the tread surface towards the sipe bottom, the sipe width gradually decreases from the tread surface to a first changing point and then gradually increases from the first changing point to the sipe bottom. At a second position, from the tread surface towards the sipe bottom, the sipe width gradually increases from the tread surface to a second changing point and then gradually decreases from the second changing point to the sipe bottom. The sipe width at the tread surface and at the sipe bottom gradually decreases in the tire circumferential direction from the first position towards the second position, and the sipe width in a tire radial intermediate portion gradually increases in the tire circumferential direction from the first position towards the second position.

An object of the present invention is to provide a tire possessing improved partial wear resistance by optimizing shapes and dimensions of a block land portion and its position and arrangement. The tire has plural block land portion arraysformed by a large number of block land portionsdefined on a tread portion. Between two block land portion arrayslocated adjacent to each other across the circumferential groove, the block land portionsconstituting the block land portion arraysare arranged on the tread portionso as to be positionally displaced from each other in the circumferential direction of the tire; a groovebetween the block land portions adjacent to each other in the width direction of the tire extends obliquely with respect to the width and circumferential directions of the tire. At this time, the distance dbetween the block land portions adjacent to each other in the width direction of the tire is shorter than the distance dbetween the block land portions adjacent to each other in the circumferential direction of the tire. Further, a length dof the block land portionin the circumferential direction of the tire falls within a range of 1.0 to 2.5% of a circumferential length of the tire.

Tire

An object of the present invention is to provide a tire possessing improved wear resistance by optimizing configurations of block land portions. The tire is configured such that, in at least two adjacent block land portion arrayssandwiching a circumferential groove, adjacent block land portionsconstituting the block land portion arraysare arranged so as to be positionally displaced from each other in the tire circumferential direction; and a distance dbetween the block land portions adjacent in the tire width direction is shorter than a distance dbetween the block land portions adjacent in the tire circumferential direction. A groove portionbetween the block land portions adjacent in the tire width direction extends obliquely with respect to the tire width direction and the tire circumferential direction. Further, plural sets each formed by at least two adjacent block land portion arrayssandwiching the circumferential grooveare arranged; and, among the block land portions arrays, an inclination angle &#x3b8;of an extending direction of the groove portionB between the block land portions adjacent in the tire width direction of block land portion arrayslocated closest to a tire equatorial plane CL side with respect to the tire circumferential direction is larger than an inclination angle &#x3b8;of an extending direction of the groove portionA between the block land portions adjacent in the tire width direction of block land portion arrayslocated at the outermost side in the tire width direction with respect to the tire circumferential direction.

An object the present invention is to provide a tire having a rib-like land portion and sipes provided therein, in which wear resistance has been enhanced by optimizing the shape of the sipes, while good fraction performance on a wet road surface is maintained. The tire has, in a tread portion, at least one row of rib-like land portion and sipes provided in the rib-like land portion. Further, depth of each sipe at least at one end portion thereof on the shoulder side is smaller than depth of the sipe at the remaining portions thereof.

Provided is a tire exhibiting both improved partial wear resistance and improved quietness. The tire has block land portion arraysdefined on a tread portion. Between adjacent two block land portion arrayssandwiching a circumferential groove, block land portionsconstituting the block land portionsare arranged so as to be positionally displaced from each other in the tire circumferential direction, and a groove portionbetween the block land portions adjacent in the tire width direction extends obliquely with respect to the tire width direction and the tire circumferential direction. Further, in the adjacent block land portion arrays, the block land portionis adjacent to at least two block land portions by way of the groove portionbetween the block land portions adjacent in the tire width direction, and two side wallsof the adjacent block land portionhas projected lengths different from each other, the projected lengths being obtained by projecting the side walls to a line parallel to the tire circumferential direction. Yet further, the block land portionsadjacent in the tire width direction are disposed in a point-symmetric manner by way of the groove portionbetween the block land portionsadjacent in the tire width direction.

Provided is a tire exhibiting improved wear resistance, partial wear resistance, and traction performance on the wet road surface. The tire has block land portion arraysdefined on a tread portion. Between two block land portion arrayslocated adjacent to each other while sandwiching a circumferential groove, a block land portionsconstituting the block land portion arrays are arrange so as to be positionally displaced from each other, and a groove portionlocated between the block land portions adjacent in the tire width direction extends obliquely with respect to tire width direction and the tire circumferential direction. At this time, a distance dbetween the block land portions adjacent in the tire width direction is shorter than a distance dbetween the block land portions adjacent in the circumferential direction. In the block land portion arraysadjacent in the tire width direction, an inclined angle &#x3b1; of a side wallof the block land portionlocated on the groove portionside with respect to the tire circumferential direction is larger than an inclined angle &#x3b2; of the other side walllocated on the opposite side to said groove portionwith respect to the tire circumferential direction.

An object the present invention is to provide a tire, in which wear resistance has been enhanced by optimizing the shape and location of block land portions. The tire has plural rowsof block land portionsformed by demarcation by providing plural circumferential groovesextending along tire circumferential direction and plural lateral groovesfor communicating adjacent two circumferential grooveswith each other; in at least two rowsof block land portions adjacent to each other with a circumferential groove therebetween, among the rowsof block land portions, the respective rowsof block land portionsare disposed to be offset with respect to each other in the tire circumferential direction. The extending direction of the groove portionbetween the block land portions adjacent to each other in the tire widthwise direction is inclined with respect to the tire widthwise direction and tire circumferential direction. A distance between the block land portions adjacent to each other in the tire widthwise direction dis shorter than a distance dbetween the block land portions adjacent to each other in the tire circumferential direction.

Tire having rows of block land portions, lateral grooves and at least three circumferential grooves

A component Fin toward an axial inner direction of the tire which is an opposite direction from an axial outer direction of the tire is applied to a force acting on a kicking endB of a land portion. With this, abrasion of the kicking end of the land portion can be moderated, and a biased abrasion resistance can be enhanced. A groove wallof a lug grooveis provided with a step portion, a tread side groove width WA in a tread side of the step portion is widened toward an axial outer side of the tire, and a width WS of the step portionis increased toward the axial outer side of the tire, thereby suppressing the lift from the road surfaceat the tread-in endA of the land portion

Pneumatic tire having lug grooves

Tread portion of an automobile tire

A pneumatic tire maintaining excellent traction performance for the entire life of the tire. The tire () has blocks () each demarcated by both a circumferential groove formed in the tread and lateral grooves crossing the circumferential groove, and also has recessed parts (). Each recessed part () is formed in at least one of those both wall surfaces of each block () that are oriented to the lateral direction of the tire, and the circumferential width (C) of each recessed part () is increased from the tread side of the block () toward the radially inside of the tire. Because the edge effect of the blocks () at the portions between the lateral grooves and the recessed parts () can be maintained in an excellent state even if the wear of the tire () progresses, the edge effect of the entire blocks can be maintained in an excellent state, and excellent traction performance can be maintained for the entire life of the tire.

A pneumatic tire including a carcass, a belt arranged at the outside of the carcass in a radial direction and having at least two belt layers, at least one belt reinforcing layer arranged so as to overlap with the belt and extend over a widthwise outer end thereof, and a tread rubber arranged at the outside of the belt in the radial direction. A pair of split auxiliary belt layers are arranged so as to overlap at least with both widthwise outer end portions of a widest-width belt reinforcing layer. Reinforcing elements having an inclination angle different from that of reinforcing elements in the belt reinforcing layer are embedded in the split auxiliary belt layer for decreasing the wearing rate at the tread end portion of the tire to effectively control irregular wear.

A pneumatic tire comprises a pair of bead portions, a pair of sidewall portion, a tread portion, a radial carcass of at least one ply, and a belt, wherein the tread portion is provided with two or more circumferential main grooves formed in a tread rubber at an inner region sandwiched by both shoulder regions and one or more circumferential ribs defined by two adjoining circumferential main grooves, and at least two circumferential fine grooves are formed in the circumferential rib.

Growing community of inventors

Kodaira, Japan

Akiyoshi Shimizu