The Yokohama Rubber Co., Ltd.

Masatoshi Kuriyama

Shinya Harikae

Masatoshi Shimizu

Masaki Sato

Noboru Kuwahara

Automobile tire

A tire has a tire center in the tire width direction. An intersection point of a carcass outer surface with a parallel line extending parallel with a rotation axis and passing through a tire maximum width position is denoted as P. An intersection point of the parallel line LP with a side surface is denoted as P. An intersection point of the parallel line with a protrusion portion outer surface of a protrusion portion is denoted as P. A distance between the tire center and the intersection point Pis denoted as W. A distance between the tire center and the intersection point Pis denoted as W. A distance between the intersection point Pand the intersection point Pis denoted as G. A distance between the intersection point Pand the intersection point Pis denoted as G. 0.80&#x2264;W/W&#x2264;0.95 and 0.1&#x2264;G/G&#x2264;1.

Pneumatic tire

A pneumatic tire includes: a center lug groove extending in a lateral direction in a center land portion, the center lug groove connecting to two main groves at both ends; an outer middle lug groove extending in the lateral direction in an outer middle land portion, the outer middle lug groove connecting to two main groves at both ends; and an inner middle lug groove extending in the lateral direction in an inner middle land portion, the inner middle lug groove including an end connecting to the main groove of the two main grooves located inward in the lateral direction and the other end terminating within the inner middle land portion; and the center lug groove and the outer middle lug groove each including a central region in a length direction including a sipe portion, the sipe portion including a sipe with a chamfered opening portion.

A pneumatic tire comprises a tread surface comprising main grooves extending in a tire circumferential direction, at least two of the main grooves adjacent in the tire circumferential direction having a wave shape with periodic oscillation; adjacent land portions in a tire lateral direction formed by the main grooves; lug grooves disposed in a row in the tire circumferential direction in the land portion formed between the wave-shaped main grooves, the lug grooves intersecting the tire circumferential direction and communicating with the wave-shaped main grooves at both ends; and narrow grooves disposed between pairs of the lug grooves adjacent in the tire circumferential direction in a row in the tire circumferential direction, the narrow grooves intersecting the tire circumferential direction, communicating with one of the main grooves at a first end, terminating within the land portion at a second end, and having a narrower groove width than the lug grooves.

A pneumatic tire comprises a tread portion with a tread surface; four main grooves in the tread surface of the tread portion, extending in a tire circumferential direction; and a center land portion, middle land portions adjacent to the center land portion on either side in a tire lateral direction, and shoulder land portions outwardly adjacent to the middle land portions in the tire lateral direction formed by the main grooves. The main grooves have a wave-like shape with a constant groove width in the tire circumferential direction and with periodic oscillation.

A pneumatic tire comprises a tread portion; four main grooves extending in a tire circumferential direction in a tread surface of the tread portion, each having a wave-like shape with periodic oscillation; a center land portion, middle land portions adjacent to the center land portion on either side in a tire lateral direction, and shoulder land portions outwardly adjacent to the middle land portions in the tire lateral direction formed by the main grooves; a plurality of lug grooves that intersect the tire circumferential direction disposed in a row in the tire circumferential direction in the land portions, the plurality of lug grooves each being disposed on a smooth, continuous curved line that crosses the land portions between the outer ends of the tread portion in the tire lateral direction.

The present technology provides a pneumatic tire that combines rolling resistance and wet grip performance while suppressing the occurrence of uneven wear. The pneumatic tire of the present technology has a cap rubber divided into a center portion that straddles a tire equator line and shoulder portions positioned on both sides thereof, a compound emphasizing wet grip performance and having a tan &#x3b4; at 0&#xb0; C. higher than that of the shoulder portions is disposed in the center portion and a compound emphasizing rolling resistance and having a tan &#x3b4; at 60&#xb0; C. lower than that of the center portion is disposed in both shoulder portions, and circumferential narrow grooves are formed on the respective shoulder sides of outermost main grooves in both the shoulder portions.

A pneumatic tire has two carcass layers including carcass cords are laid between a pair of bead portions, bead cores and bead fillers are disposed in the bead portions, and at least two belt layers are disposed on the outer circumferential side of the carcass layers, the tire being characterized in that both ends of the inner carcass layer are folded back from the tire inner side to the tire outer side around the bead cores, and the ends of the folded back portions of the inner carcass layer are disposed between the innermost belt layer and the outer carcass layer, while both ends of the outer carcass layer are disposed so as to pass between a main portion of the inner carcass layer and the bead fillers, and both ends of the outer carcass layer terminate at the bead portions without being folded back around the bead cores.

Pneumatic Tire

A pneumatic tire with five land parts formed by four circumferential main grooves wherein middle land parts each include a first sub groove and a second sub groove that are formed independently and arranged alternately in the tire circumferential direction on two sides of the middle land part in the tire width direction, the first sub groove being formed by the lug groove having one end thereof opening to one of the circumferential main grooves and the other end terminating in the middle land part, the second sub groove being formed by the lug groove having one end thereof opening to one of the circumferential main grooves and the other end terminating in the middle land part, and the middle land part further includes a concave part on a wall on an outer side of the middle land part in the tire width direction and spaced by each sub groove.

A belt cover layer is provided on an outer circumferential side of a belt layer. The belt cover layer is constituted by a band-like member in which steel cords are embedded in rubber. Adjacent revolution portions of the band-like member are wound spirally in a tire circumferential direction so as not to contact each other in a region of at least 50% of a belt width centered on a tire equator. A load-strain curve of the steel cords has an inflection point in a strain region of 1% to 3.5%. An average elastic modulus when the steel cords are subjected to a load from 50 N to 100 N is from 25 GPa to 100 GPa.

Growing community of inventors

Hiratsuka, Japan

Masatoshi Kuriyama