The Yokohama Rubber Co., Ltd.

Masaaki Nagayasu

Hiroshi Furusawa

Ryohei Takemori

Yuki Sasaya

Atsushi Tanno

Kenichi Sato

Jun Matsuda

Hiraku Kouda

Yoshimasa Hashimoto

Kenichiro Endo

Kenichirou Endou

Hiraku Koda

In a pneumatic tire, a tread portion including rows of land portions defined by circumferential grooves extending in a tire circumferential direction is formed by sectors divided in the tire circumferential direction, sipes extending in a tire width direction formed in the land portions include a three-dimensional sipe, whose shape tread surface changes along a sipe depth direction, and a two-dimensional sipe, whose shape is constant along the sipe depth direction, and a ratio Rof a number of the three-dimensional sipes with respect to a total number of the sipes in a first boundary region, which is within 15 mm on one side of a sector dividing position in the tire circumferential direction, and a ratio Rt of a number of the three-dimensional sipes with respect to a total number of the sipes in all of the tread portion satisfy relationship R<Rt.

Pneumatic tire

A pneumatic tire includes a tread portion molded by sectors divided in a tire circumferential direction. The pneumatic tire includes circumferential grooves, rows of land portions, and sipes. The circumferential grooves extend in the tire circumferential direction in the tread portion. The rows of land portions are defined by the circumferential grooves. The sipes extend in a tire width direction in at least one row of the rows of land portions. The sipes include at least one shallow bottom sipe and regular sipes. The at least one shallow bottom sipe is disposed in a boundary region including a dividing position of each of the sectors. The regular sipes are disposed at positions more separated from the dividing position of each of the sectors than the at least one shallow bottom sipe. The at least one shallow bottom sipe is shallower than the regular sipes.

A pneumatic tire includes protrusion portions formed on at least one tire side portion of tire side portions located on both sides in a width direction, projecting from a tire side surface that is a surface of the tire side portion, and extending along the tire side surface, the protrusion portions having an angle α within a range of no less than 6% and no more than 50% of an angle of one round in a circumferential direction, the angle α being relative and in the circumferential direction between two protrusion portion end position lines that respectively extend in a radial direction through different end portions of both end portions in an extending direction of the protrusion portions, and the tire side portion having a thickness at a tire maximum width position within a range of no less than 2 mm and no more than 9 mm.

A tire includes a tread, sidewalls, beads, and pairs of first and second grooves formed in the tread. A first land is between the first grooves, and second lands are between one of the first and second grooves and between another of the first and second main grooves. First sipes and lateral grooves are in the first land, at the same angle, the first sipes being connected to the lateral grooves. The first sipe and the lateral groove open to one of the first grooves. Second sipes and auxiliary grooves are in a bent shape in the second land. The first and second sipes are oriented the same. The auxiliary groove includes first and second portions. An intersection angle of the first portion with the second sipe is within 45&#xb0; to 90&#xb0;. A length a of the first portion and a length b of the second portion satisfy 0.05&#xd7;a&#x2264;b&#x2264;0.4&#xd7;a.

A pneumatic tire is provided. In a meridian cross-section, an external contour shape of the bead core is a polygon formed by common tangent lines of a plurality of circumferential portions of a bead wire, the external contour shape includes a single vertex located toward the outside in a tire radial direction, an internal angle formed by two sides sandwiching the vertex is an acute angle, a bottom side of the external contour shape is inclined with respect to the tire lateral direction by from 2&#xb0; to 9&#xb0;, and the carcass layer is bent and folded back along a circumference of the bead core in a bead portion, a folded back portion of the carcass layer from a position of an outer end of the bead core in the tire radial direction extends toward a sidewall portion in contact with a body portion.

Of layers configuring a bead core of a pneumatic tire, the width Wof one of the layers including the greatest number of rows, the width W, Wof other of the layers located respectively innermost and outermost in the radial direction satisfy W&#x3e;Wand W&#x2264;0.5&#xd7;W. The position of width Wis inward in the radial direction of the center of the bead core. A carcass is folded and curved along the bead core and extends toward sidewalls where a folded back portion of the carcass contacts a body of the carcass. A rubber occupancy ratio in a closed region formed by the body and the folded back portion is 0.1% to 15%. The cross-sectional area Sand hardness Hof a filler outward of the carcass in the lateral direction, and the cross-sectional area Sand the hardness Hof the side reinforcing layer satisfy 0.12&#x2264;(S&#xd7;H)/(S&#xd7;H)&#x2264;0.50.

In a cross-section of a pneumatic tire, a contour of the bead core is a polygon formed by tangent lines of circumferential portions of a bead wire, the contour includes a vertex with an acute angle and a bottom side opposite the vertex, the carcass layer is folded back along a circumference of the bead core in a bead portion, a folded back portion of the carcass layer from an outer end of the bead core extends in the radial direction, and a distance in the radial direction between a center of an arc profile of a tire outer surface and a straight line extending in the lateral direction through the vertex is within 20% of a radius r of the arc, and a distance in the lateral direction between the center of the arc and a straight line extending in the radial direction through the vertex is within 2r&#xb1;0.4r.

In a pneumatic tire including a side reinforcing layer, the maximum width Wof a bead core and the widths W, Wof the bead core at innermost and outermost sides in the radial direction, respectively, satisfy W&#x3e;Wand W&#xd7;W. Wis toward the inside of the center of the bead core in the radial direction. A carcass is folded and curved along the bead core, and a folded back portion of the carcass extends toward the sidewalls while contacting a body of the carcass. A rubber occupancy ratio in a region formed by the body and the folded back portion of the carcass is 0.1% to 15%. The cross-sectional area Sof a filler toward the outside of the carcass in the lateral direction, the hardness Hof the filler, the cross-sectional area Sof a side reinforcing layer and the hardness Hof the side reinforcing layer satisfy 0.15&#x2264;(S&#xd7;H)/(S&#xd7;H)&#x2264;0.60.

A pneumatic tire includes blocks arranged in the tread center region that is X % (30&#x2266;X&#x2266;70) of the tread contact width TW with the tire equator C as center are formed elongated in the tire circumferential direction so that the block ratio is not less than 1.5. At least one end in the longitudinal direction of the sipes provided in the blocks connects to a longitudinal groove. A protrusion and a recess that can engage with each other are provided on the sipe wall surfaces that face each other constituting the sipes, at the end portion in the longitudinal direction of the sipes that connect with the longitudinal groove.

In a pneumatic tire, a single block includes a first sipe and a second sipe each extending in a tire width direction and disposed at a predetermined pitch in a tire circumferential direction. The first sipe and the second sipe include a first sipe portion that has a linear form when the block is viewed planarly, and a second sipe portion that has a zigzag shape when the block is viewed planarly and that connects to the first sipe portion. The first sipe portion includes a pair of sipe wall faces that face each other and have a linear form when viewed as a cross-section from a direction perpendicular to a sipe length direction, and includes a protrusion disposed on a first face of the sipe wall faces and a recess disposed on a second face of the sipe wall faces so as to mate with the protrusion.

A pneumatic tire having improved performance on ice and wet road surfaces without degradation of steering stability on dry road surfaces. The pneumatic tire includes a tread portion, side wall portions, bead portions, a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of lateral grooves extending in the tire width direction provided in the tread portion, a plurality of blocks partitioned by the circumferential and lateral grooves, and a plurality of sipes extending in the tire width direction in each block. At least some sipes include a main body part located centrally in the block width direction, and a deep-bottomed communicating portion that communicates with the circumferential groove adjacent to the block and has a depth not less than 50% the depth of the circumferential groove, and mutually mating convex and concave portions are formed locally in opposing surfaces in the deep-bottomed communicating portion.

A plurality of blocks is provided in a tread portion and a plurality of sipes is provided in a tread surface of the blocks. In the sipes, protrusions are formed on a first sipe wall surface of mutually opposing sipe wall surfaces and recesses that engage with the protrusions are formed on a second sipe wall surface. Collapsing of the portions of the blocks sandwiched by the sipes is suppressed due to the engaging of the protrusions and the recesses. A height of the protrusions provided on the sipe wall surfaces of the sipes located at the edges in the tire circumferential direction is greater than a height of the protrusions provided on the sipe wall surfaces of the other sipes. Specifically, a force that works to suppress bending deformation increases and collapsing of the portions of the blocks located at the edges in the tire circumferential direction is suppressed.

A pneumatic tire includes sipes extending in a tire width direction on a road contact surface of blocks, the sipes having at least one end open to a circumferential main groove. The sipes are positioned at an edge portion of the blocks, and have a first sipe portion open to the circumferential main groove and a second sipe portion positioned at a center portion of the blocks. The first sipe portion has a linear form when viewed as a cross-section from a direction perpendicular to a sipe length direction, and has a pair of mutually mating, opposing first sipe wall faces with a protrusion and a recess respectively disposed thereon. The second sipe portion has a form bent in the sipe width direction when viewed as a cross-section from a direction perpendicular to the sipe length direction, and has a pair of mating mutually opposing second sipe wall faces.

A pneumatic tire wherein a sipe includes protrusions on a first sipe wall face of mutually opposing sipe wall faces and recesses that mate with the protrusions in a second sipe wall face. Additionally, in a projection figure of the protrusions with the sipe wall faces in an expanded state, a relationship between a placement density X of the protrusions in a region that extends up to half of a sipe depth H from an opening of the sipe and a placement density Y of the protrusions in a region that extends up to half of the sipe depth H from a bottom of the sipe is X&#x3e;Y.

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Hiratsuka, Japan

Masaaki Nagayasu