Sumitomo Rubber Industries Limited

Hirokazu Takano

Keiji Higuchi

Toshio Koyama

A pneumatic tyre includes a tread portion including a shoulder land portion having a tread edge. The shoulder land portion is provided with shoulder lateral grooves extending inwardly in a tyre axial direction from the tread edge so as to define shoulder block elements therebetween, and at least one protrusion protruding from an outer surface in the tyre axial direction of the respective shoulder land portion. The protrusion includes first portions provided on the respective shoulder block elements and extending in a tyre radial direction, and a second portion located inwardly in the tyre radial direction of one of the shoulder lateral grooves and extending in a tyre circumferential direction to connect inner portions of at least two first portions.

Pneumatic tyre

A tire having a tread portion with: zigzag shoulder main grooves having a trapezoidal wave form comprising first and second circumferential segments and first and second oblique segments; and shoulder axial grooves extending from the shoulder main grooves beyond the tread edges. The shoulder axial grooves are respectively smoothly continued to the first oblique segments or the second oblique segments so as to form composite shoulder axial grooves whose groove widths are smoothly increased toward the axially outside of the tire.

Tire

A tire comprises a tread portioncomprising at least a first main grooveand a second main grooveextending continuously in a tire circumferential direction. The first main groovecomprises a first oblique portioninclined with respect to the tire circumferential direction and a second oblique portionconnected with the first oblique portion and inclined in an opposite direction to the first oblique portion. The second main groovecomprises a third oblique portioninclined in a same direction as the first oblique portionwith respect to the tire circumferential direction, a fourth oblique portioninclined in an opposite direction to the third oblique portion, and a longitudinal groove portiondisposed between the third and fourth oblique portionsandso that they are not directly connected and extending along the tire circumferential direction.

Tire for automobile

A pneumatic tire includes a tread portion provided with at least one circumferentially extending main groove, and at least one lateral groove extending from the main groove. The at least one lateral groove comprises a bottom, and at least one stepwise groove wall that includes at least one level part, wherein the number of level part is not more than three. In a cross-sectional view of the lateral groove, a depth Da from a ground contacting surface of the tread portion to a radially innermost level part is in a range of from 50% to 80% a maximum groove depth D4 of the lateral groove, and a width Wa from the radially innermost level part to a groove edge of the stepwise groove wall measured along in a groove width direction is in a range of from 50% to 150% the depth Da.

Pneumatic tire

A pneumatic tire has a tread portion provided with a center land portion defined between two crown main groovesextending continuously in the tire circumferential direction. The widthwise center line of the crown main groove is made up of successively-arranged circular arcs all oriented toward the same axial direction. The center land portion is provided in its both sides with sloping-surface portions each defined by a sloping surface extending from the radially outer surface of the center land portion to the axially inner groove-sidewall surface of one of the crown main grooves. Each of the sloping-surface portions includes, in its circumferential extent, the circumferential position of one of axially outermost points of the widthwise center line of the adjacent crown main groove.

A pneumatic tire comprises a tread portion provided with a circumferential shoulder main groove, shoulder lateral grooves extending from the shoulder main groove toward a tread edge, and middle lateral grooves extending from the shoulder main groove toward a tire equatorial plane, the shoulder main groove extending in a zigzag manner through an axially innermost and outermost points alternately, each middle lateral groove extending from each innermost point of the shoulder main groove with an angle of 50-75 degrees with respect to a tire axial direction, and each shoulder lateral groove extending from the shoulder main groove with the same inclination direction with the middle lateral groove at an angle of 10-25 degrees with respect to the tire axial direction, wherein the number of shoulder lateral grooves is larger than the number of middle lateral grooves.

A pneumatic tire comprises a tread portion provided with a shoulder main groove, shoulder lateral grooves extending from the shoulder main groove toward axially outwardly, the shoulder main groove extending in a zigzag manner comprising linear portions and curved portions which are arranged alternately in a circumferential direction of the tire, each linear portion inclined with respect to the circumferential direction of the tire, each curved portion having a radius of curvature of from 12-80 mm, the curved portion protruding toward axially outwardly of the tire, the shoulder main groove having a pair of groove edges and a circumferential space therebetween which straightly extends along the circumferential direction of the tire without coming into contact with both groove edges and the circumferential space with an axial width of from 0.2 to 0.7 times an axial groove width of the shoulder main groove.

In a pneumatic tire, a center land portionbetween center main grooves, a middle land portionbetween the center main grooveand a shoulder main groove, and a pair of shoulder land portionsextending on outer sides of the shoulder main groovein a tire axial direction are divided from each other. The center main grooveincludes arc groove pieceswhich are continuously provided in a tire circumferential direction. The arc groove pieceincludes an arc portionwhich is curved to swell toward a tire equator C. The middle land portionis provided with a middle inclined groovewhich extends from an intersection portion K of the arc groove piecetoward the shoulder main groove

A pneumatic tire comprises a plurality of protect ribs extending at an angle &#x3b1; of 0 to 20&#xb0; with respect to a tire radial direction line and provided on outer surfaces S of sidewall portions at distances from each other in a circumferential direction of a tire. Each of the protect ribs includes a maximum height portion whose height from the outer surface S is maximum. A vertical cross section shape which passes through the maximum height portion is of substantially triangular shape. This s substantially triangular shape includes an outer end-side inclined portion having the height which is gradually reduced from the maximum height portion to a radial outer end Ra, and an inner end-side inclined portion having the height which is gradually reduced from the maximum height portion to a radial inner end Rb. A distance La between the maximum height portion and the radial outer end Ra in the length direction is in a range of 0.1 to 0.3 times of a distance LR in the length direction between the radial outer end Ra and the inner end Rb of the protect rib, and a tire radial distance Ha between the radial outer end Ra of the protect rib and a bead base line is in a range of 0.6 to 0.8 times of a tire cross section height HT.

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Kobe, Japan

Hirokazu Takano