The Yokohama Rubber Co., Ltd.

Risa Tauchi

Hideki Hamanaka

Yukihito Yamaguchi

Toshiyuki Sato

Shoei Kakuta

Takamasa Motomitsu

Mitsuru Manabe

A pneumatic tire is mounted on a 5&#xb0; rim. A bead core includes a bottom inclined 0&#xb0;-5&#xb0; in a direction in which the bottom diverges outward in the radial direction as the bottom extends from an inner side toward an outer side in the width direction. A bead includes a base, a toe, a heel, and a back surface. The heel connects to the back surface by an arc. The base includes a region between a core lower inner end position on an inner circumferential surface of the bead and being identical to a position of a bead core inner end and a core lower outer end position on an inner circumferential surface of the bead and being identical to a position of a bead core outer end in the width direction. The base has a curved line projecting toward the inner side in the radial direction in a cross-section.

Pneumatic tire

A pneumatic tire includes: a carcass layer wrapping a bead core and a bead filler and being turned back; a steel chafer formed by steel cords and disposed between the carcass layer and a rim fitting surface; and sub-chafers between the steel chafer and the rim fitting surface and made of organic fiber. The steel chafer includes an outer end portion outward of the bead filler in a tire lateral direction. The outer end portion has a height from 0.5 times to 0.7 times a height of a rim flange. The sub-chafers each include an outer end portion outward of the bead filler in the tire lateral direction. The outer end portion has a height from 0.7 times to 0.9 times a height of a rim flange. The carcass layer has a turned up height from 2.5 times to 4.5 times a height of a rim flange.

A pneumatic tire includes a tread portion with shoulder lug grooves spaced apart in a circumferential direction, each extending outward in a tire lateral direction, opening to a ground contact end, and including a closed end inward in the tire lateral direction. In a region of each of the shoulder lug grooves from an end of a belt having a greatest width in a belt portion of the pneumatic tire to an inner side in the tire lateral direction, the shoulder lug groove has a groove width that decreases inward in the tire lateral direction, and includes a portion where a groove cross-sectional area is kept constant by a change in at least one of a groove wall angle or a groove depth of the shoulder lug groove, the portion being provided in the tire lateral direction across a length of at least 20% of half a tire development width.

Pneumatic tire and pneumatic tire manufacturing method

In a pneumatic tire on a rim with 5&#xb0; taper, a bead core includes a bead core bottom inclined 0&#xb0; to 5&#xb0; with respect to a rotation axis in a direction in which the bead core bottom extends outward in a radial direction from an inner side toward an outer side in the lateral direction, a bead portion includes a bead base portion inclined 8&#xb0; to 12&#xb0; with respect to the rotation axis in a direction in which the bead base portion extends outward in the radial direction from the inner side toward the outer side in the lateral direction. A bead width BW is a distance between tire inner and outer surfaces on a straight line through a bead core center in the meridian cross-section and parallel to the bead base portion. The bead core has a maximum width CW within a range of (BW&#xd7;0.54)&#x2264;CW&#x2264;(BW&#xd7;0.58).

A pneumatic tire includes cross belts and one or more protective belts provided in the tire radial direction. A width of a widest protective belt is greater than a width of any of the cross belts. In the tire profile, a maximum projection position of the widest protective belt is A, an end position of the widest protective belt is B, a position at which a straight line a passing through position A extending in the direction normal to a tread surface intersects with the tread surface is A', and a position at which a straight line b passing through position B extending in the direction normal to the tread surface intersects with the tread surface is B&#x2032;. An angle formed between a first straight line that links position A and position B and a second straight line that links position A&#x2032; and position B&#x2032; is from 0&#xb0; to 15&#xb0;.

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.

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.

Heavy duty pneumatic 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.

Heavy-duty pneumatic tire

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.

Growing community of inventors

Hiratsuka, Japan

Risa Tauchi