The Yokohama Rubber Co., Ltd.

Yukihito Yamaguchi

Hideki Hamanaka

Risa Tauchi

Toshiyuki Sato

Shoei Kakuta

Takamasa Motomitsu

Naoshi Miyashita

Satoru Isobe

Kazunori Yamawaki

Mitsuru Manabe

A pneumatic tire comprises a carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and tread rubber disposed on the outer side in the tire radial direction of the belt layer. The belt layer is formed by laminating a pair of cross belts having belt angles with an absolute value from 10&#xb0; to 45&#xb0; both inclusive and mutually opposite signs, and a circumferential reinforcing layer having a belt angle within a range of &#xb1;5&#xb0; relative to the tire circumferential direction. The distance (Gcc) from the tread profile to the tire inner circumferential surface along the tire equatorial plane and the distance (Gsh) from the tread edge to the tire inner circumferential surface have a relationship satisfying 1.10&#x2264;Gsh/Gcc. The groove depth (Dsh) and under-groove gauge (UDsh) of the outermost circumferential main groove have a relationship satisfying 0.20&#x2264;UDsh/Dsh.

Pneumatic tire

A tread pattern of a heavy duty pneumatic tire includes: a linear shaped center lug groove; a pair of circumferential main grooves formed in a wave shape in a tire circumferential direction; a center block; and a central narrow groove that does not have a linear shape, having an opening end that opens in the adjacent center lug grooves in a tire lateral direction position excluding on a tire equator line, and having a groove width that is narrower than the groove width of the shoulder lug groove. The groove width of the center lug groove and the circumferential main groove is narrower than the groove width of the shoulder lug groove. The central narrow groove has a portion that extends outwards in a tire lateral direction from the opening end in the half tread region where the opening end is positioned.

Heavy-duty pneumatic tire

A heavy duty pneumatic tire includes a tread pattern that includes circumferential main grooves, a center wide groove extending in a center region between the circumferential main grooves, and center lug grooves disposed in a first center region and a second center region on either side of the center wide groove in the tire lateral direction, the center lug grooves having a linear shape and opening to the center wide groove. The center lug grooves and the circumferential main grooves have a narrower groove width than shoulder lug grooves disposed in a shoulder region. The center lug grooves of the first center region and the center lug grooves of the second center region extend parallel with one another. The center wide groove has a constant groove depth that is shallower than the maximum groove depth of the circumferential main grooves and the center lug grooves.

Heavy duty pneumatic tire

A pneumatic tire includes a plurality of center lug grooves disposed at intervals in a tire circumferential direction that extend crossing a tire equator line and include a first groove turning portion and a second groove turning portion; a plurality of shoulder lug grooves disposed in the intervals between the plurality of center lug grooves in the tire circumferential direction extending outward in the tire width direction, an inner end in the tire width direction being disposed outward of an end of the center lug groove in the tire width direction; a pair of circumferential main grooves to which the ends of the center lug grooves and the inner ends of the plurality of shoulder lug grooves in the tire width direction alternately connect; and a circumferential secondary groove disposed around the entire circumference of the pneumatic tire with a wave-like shape.

This pneumatic tire () includes: a pair of bead cores (); a carcass layer () extending between the pair of bead cores (); and a belt layer () including a laminate of at least four belt plies (to) having steel belt cords covered with coating rubber, the belt layer being disposed on the outer side in a tire radial direction of the carcass layer (). An inter-cord distance (Ga) between an outermost layer belt ply (fourth belt ()) and an adjacent belt ply (third belt ()) has a relationship such that 0.80&#x2264;Ga/&#x3c6;max&#x2264;1.80 with respect to a maximum value (&#x3c6;max) of outer diameters (&#x3c6;) of belt cords () in the outermost layer belt ply () and the adjacent belt ply ().

A tread pattern is provided with: shoulder lug grooves open at ground contact ends; center lug grooves each having opposite ends; circumferential primary grooves each formed in a wavy shape by connecting ends of the center lug grooves and the inner ends of the shoulder lug grooves in the width direction of the tire; and center blocks defined by the center lug grooves and the pair of circumferential primary grooves. The width of the circumferential primary grooves is smaller than the width of the shoulder lug grooves. The center lug grooves are tilted relative to both the circumferential direction and the width direction of the tire and each have a third groove turning portion and a fourth groove turning portion which protrude in the different directions in the circumferential direction of the tire.

A tread pattern of a pneumatic tire comprises shoulder lug grooves that open to ground contact edges; center lug grooves; a pair of circumferential primary grooves with a narrower groove width than the shoulder lug grooves, wherein a portion that bends outward in the tire width direction connects to the shoulder lug grooves and a portion that bends inward in the tire width direction connects to the center lug grooves; and center blocks defined by the center lug grooves and the circumferential primary grooves. The circumferential primary grooves are on opposite sides in the tire width direction in regions spaced from a center line by a distance of from 30% to 60% of half of a tread width T. The ratio of the groove width P3 of the center lug grooves to the maximum length LB in the tire circumferential direction of the center blocks is from 0.03 to 0.07.

Pneumatic tire for heavy loads

A pneumatic tire includes center lug grooves disposed at intervals in a tire circumferential direction that extend crossing a tire equator line and include a first groove turning portion and a second groove turning portion; shoulder lug grooves disposed in the intervals between the center lug grooves in the tire circumferential direction extending outward in the tire width direction, an inner end in the tire width direction being disposed outward of an end of the center lug groove in the tire width direction; a pair of circumferential main grooves to which the ends of the center lug grooves and the inner ends of the shoulder lug grooves in the tire width direction alternately connect; and a circumferential secondary groove disposed around the entire circumference of the pneumatic tire that intersects the center lug grooves between the first groove turning portion and the second groove turning portion.

Provided is a heavy duty pneumatic tire that includes a tread portion including, in a tread pattern: shoulder lug grooves extending outward in the tire width direction and opening at ground contact edges; a pair of circumferential primary grooves; center lug grooves; center blocks defined by the center lug grooves and the pair of circumferential primary grooves and aligned in the tire circumferential direction; and circumferential secondary grooves extending in the tire circumferential direction in the center block regions and opening to the center lug grooves adjoining the center blocks. The circumferential secondary grooves extend in the tire circumferential direction while changing positions in the tire width direction and each include third groove turning portions formed into a bent shape or a curved shape. The ratio P4/P1 of the width P4 of the circumferential secondary grooves to the width P1 of the circumferential primary grooves is from 0.70 to 1.10.

A tread pattern is provided with: shoulder lug grooves open at ground contact edges; center lug grooves having two ends; circumferential primary grooves formed in a wave-like shape by alternately connecting ends of the center lug grooves and the inner ends in the tire width direction of the shoulder lug grooves; and center blocks defined by the center lug grooves and the pair of circumferential primary grooves. The belt portion of the tire includes first cross belt layers and second cross belt layers. The ratio of the width WB of the center blocks in the tire width direction to the belt width Wof the belt layer having the shortest width in the tire width direction among the first cross belt layers is in the range from 0.6 to 0.9.

The present technology provides a heavy duty pneumatic tire with a tread portion having a tread pattern including: a pair of circumferential primary grooves defined in a wave-like shape and extending in the tire circumferential direction; center lug grooves; center blocks; and circumferential secondary grooves extending in regions of the center blocks and open to the center lug grooves. The center lug grooves have two groove turning portions turned in a bend shape or a curved shape. The circumferential secondary grooves extend in an inclined manner relative to the tire circumferential direction. An inclination angle (&#x3b8;) of the circumferential secondary grooves relative to the tire circumferential direction is different from an inclination angle (&#x3b8;) of portions of the circumferential primary grooves relative to the tire circumferential direction, the portions extending toward the same side as a side in the tire width direction, toward which the circumferential secondary grooves are inclined.

A heavy-duty pneumatic tire includes a tread pattern including center lug grooves, shoulder lug grooves, a pair of circumferential primary grooves formed in wave-like shapes by alternately connecting ends of the center lug grooves and ends of the shoulder lug grooves and having a smaller width than the width of the shoulder lug grooves, center blocks defined by the center lug groove and the circumferential primary grooves, and a circumferential secondary groove extending in the tire circumferential direction so as to divide regions of the center blocks. The belt portion includes two or greater pairs of belts. The ratio of the width Wof a belt having a smaller width in each of the belt pairs to the width Wof a belt having a greater width is 0.75 or greater and 0.90 or less.

A pneumatic tire with improved heat build-up resistance in a land portion in a tread center region. The pneumatic tire is provided with a tread pattern that includes a plurality of center lug grooves () disposed at intervals in a tire circumferential direction that cross a tire equator line; a plurality of shoulder lug grooves (A,B) disposed in intervals between the plurality of center lug grooves in the tire circumferential direction extending outward in the tire width direction, an inner end in the tire width direction being disposed outward of an end of the center lug groove in the tire width direction; a pair of circumferential primary grooves (A,B) extending around an entire circumference of the pneumatic tire in a wave-like shape with the ends of the center lug grooves and the inner ends of the plurality of shoulder lug grooves in the tire width direction alternately connecting to the pair of circumferential primary grooves (A,B); and A straight line that joins an intersection portion between the center lug groove and the circumferential secondary groove and the end of the center lug groove has an inclination angle with respect to the tire circumferential direction ranging from 55&#xb0; to 75&#xb0;.

A pneumatic tire having a tread pattern includes: shoulder lug grooves opening at ground contact edges; center lug grooves having both ends; circumferential primary grooves being formed to wave-like shape and alternately connecting the ends of the center lug grooves and inward ends of the shoulder lug grooves in the tire width direction; center blocks formed in a row defined by the center lug grooves and the pair of circumferential primary grooves; and circumferential secondary grooves being formed in regions of the center blocks and interconnecting center lug grooves adjacent in the tire circumferential direction. The circumferential secondary grooves have secondary groove turning portions, and the center lug grooves have lug groove turning portions and connect to the circumferential secondary grooves at the lug groove turning portions.

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Hiratsuka, Japan

Yukihito Yamaguchi