Bridgestone Corporation

Keita Yumii

Masashi Yamaguchi

Hiraki Iwasa

A pneumatic tire includes, on a tread surface, circumferential main grooves extending in the tread circumferential direction, rib-like land portions defined between circumferential main grooves adjacent in the tread width direction or by circumferential main grooves and tread edges, and resonators, arrayed circumferentially in the rib-like land portions, each including a narrowed neck and an air chamber. The narrowed neck is a widthwise sipe opening at one end to the circumferential main groove that defines the rib-like land portion, extending therefrom in the tread width direction, and terminating at another end within the rib-like land portion. The air chamber is a circumferential sipe connected to the other end of the widthwise sipe, extending in the tread circumferential direction, terminating at both ends within the rib-like land portion, and including a first widened portion, at the sipe bottom, with a larger sipe width than at the tread surface side.

Pneumatic tire

A pneumatic tire includes circumferential main grooves extending in the tire circumferential direction on the tread surface, and in widthwise outermost land portions, widthwise grooves extending from the tread edges inward in the tire width direction and widthwise sipes extending from the tire widthwise inner edge of the widthwise grooves inward in the tire width direction and connecting to the circumferential main groove. Each widthwise sipe includes a widened portion, by the sipe bottom, with a larger sipe width than at the tread surface. A rectangle ratio is less than 0.8. In a tire radial region containing the widened portion, the widened portion includes a portion extending at a first angle relative to the tire width direction. In plan view of the tread surface, each widthwise sipe extends along the tire width direction or at a second angle smaller than the first angle relative to the tire width direction.

A pneumatic tire includes circumferential main grooves extending in the tire circumferential direction on the tread surface, and in widthwise outermost land portions, widthwise grooves extending from the tread edges inward in the tire width direction and widthwise sipes extending from the tire widthwise inner edge of the widthwise grooves inward in the tire width direction and connecting to the circumferential main groove. Each widthwise sipe includes a widened portion, by the sipe bottom, with a larger sipe width than at the tread surface. A rectangle ratio is 0.8 or more. Each widthwise sipe extends at a first angle relative to the tire width direction in plan view of the tread surface. In a tire radial region containing the widened portion, the widened portion extends at a second angle smaller than the first angle relative to the tire width direction, or partially extends along the tire width direction.

A tire according to the present disclosure is a tire including, in a tread surface, a tread land portion partitioned by a partitioning groove or by the partitioning groove and a tread edge. The tread land portion includes a sipe extending from a surface of the tread land portion inwardly in a tire radial direction. The sipe includes a widened portion with a larger sipe width than a position adjacent in a sipe longitudinal direction. The cross-sectional area of the widened portion in cross section perpendicular to the tire radial direction is larger on inside than on outside in the tire radial direction.

Tire

At a run-flat tire, given that an average radius of curvature of a case line between an intersection point (0.1SHp) and an intersection point (0.2SHp) when viewed in a cross-section along a tire rotation axis is radius R1, and that an average radius of curvature of the case line between an intersection point (0.4SHp) and an intersection point (0.6SHp) when viewed in the cross-section along the tire rotation axis is radius R2, ratio R2/R1 is set to be greater than 0.3.

Run-flat tire

The pneumatic tire includes: a pair of bead portions; a pair of sidewall portions; a tread portion; a carcass; a reinforcing rubber layer, a tire widthwise cross-section of the reinforcing rubber layer having a substantially crescent shape; an inclined belt including at least one inclined belt layer formed by a plurality of cords extending at an inclination to a tire circumferential direction and covered with rubber; and an inner liner provided on an inner peripheral surface of a tire body in at least the tread portion. In a tire widthwise cross-sectional view, an edge of the inner liner is positioned farther outward in the tire radial direction than a tire maximum width position of the pneumatic tire and farther inward in the tire radial direction than a perpendicular from a tire widthwise edge of the inclined belt to the inner peripheral surface of the tire body.

This tire is provided with reinforcing cord layers that reinforce a bead part. The reinforcing cord layers are such that at the bead part at the inner side of vehicle mounting, the number of layers of the reinforcing cord layers with respect to a bead filler is greater at the inner side in the direction of tire width compared to the outer side in the direction of tire width with respect to the bead filler, and at the bead part at the outer side of vehicle mounting, the number of layers of the reinforcing cord layers with respect to the bead filler is greater at the outer side in the direction of tire width compared to the inner side in the direction of tire width with respect to the bead filler.

A pneumatic tire reduces the columnar resonance noise of the tire while controlling the lowering of wet performances, wherein four circumferential grooves continuously extending in the circumferential direction of the tire are disposed in a treading face and a plurality of lateral grooves each having one end opened to the circumferential groove and terminated in a land portion are formed with respect to two circumferential grooves among the four circumferential grooves, and these lateral grooves and the respective circumferential grooves have such a groove width that both groove walls of the groove do not contact with each other in a ground contact face and one or more lateral groove are always completely included in the ground contact face, and an extending length of a portion of each lateral groove in the ground contact face having a groove width of the lateral groove corresponding to not less than 30% of a groove width of the circumferential groove is made not less than 40% of an extending length of the circumferential groove in the ground contact face.

Pneumatic tire and method of designing tread pattern thereof

Pneumatic tire and method of designing tread pattern of the tire

Pneumatic tire with tread having lateral grooves

Provided is a run-flat tire having a substantially-crescent-shaped cross section, which makes it possible to achieve both durability at the time of run-flat travel and ride comfort at the time of travel at a normal inner pressure. A rigidity reducing portion that reduces a tire rigidity in the width direction extends in the circumferential direction on a surface of a tread rubber in an area located on the inner side than an end of a belt in the tire width direction and on the outer side than a road-contacting end in the tire width direction under a 75% load state.

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Kodaira, Japan

Keita Yumii