Sumitomo Rubber Industries Limited

Satoshi Tsuda

Minoru Nishi

Shingo Takahashi

Takahiro Kimishima

Kiyoto Maruoka

Atsushi Yamahira

Mitsuharu Koya

Shinichi Matsuura

Masakazu Washizuka

Takeshi Kuroki

Jyunji Ohira

It aims to provide a heavy duty pneumatic tire with block patterns and capable of improving deflected wear resisting performances without sacrificing wet grip performances or on-snow performances and that can particularly be favorably used for all seasons. The present invention comprises block patterns employing at least three types of blockscomprised of central blocksC delimited by the central longitudinal grooveM, the intermediate longitudinal groovesM, and the central lateral groovesC, intermediate blocksM delimited by the intermediate longitudinal groovesM, the outer longitudinal groovesS and the intermediate lateral groovesM, and outer blocksS that are delimited by outer longitudinal groovesS, outer lateral groovesS that extend from this outer longitudinal groovesS to the tread ends E, and wherein longitudinal length ratios (L/W) of blocks, groove width ratios of longitudinal grooves and lateral grooves (w/w), maximum widths of blocks, minimum widths of blocks and ratios thereof (Wmax/Wmin), and circumferential edge components and tire axial edge components and ratios thereof (EC/EL) at respective stages of wear are defined to be within specified ranges.

Heavy duty pneumatic tire

It aims to provide a heavy duty pneumatic tire with block patterns and capable of improving deflected wear resisting performances without sacrificing wet grip performances or on-snow performances and that can particularly be favorably used for all seasons. The present invention comprises block patterns employing at least three types of blockscomprised of central blocksC delimited by the central longitudinal grooveM, the intermediate longitudinal groovesM, and the central lateral groovesC, intermediate blocksM delimited by the intermediate longitudinal groovesM, the outer longitudinal groovesS and the intermediate lateral groovesM, and outer blocksS that are delimited by outer longitudinal groovesS, outer lateral groovesS that extend from this outer longitudinal groovesS to the tread ends E, and wherein longitudinal length ratios (L/W) of blocks, groove width ratios of longitudinal grooves and lateral grooves (w/w), maximum widths of blocks, minimum widths of blocks and ratios thereof (W4max/W4min), and circumferential edge components and tire axial edge components and ratios thereof (EC/EL) at respective stages of wear are defined to be within specified ranges.

A heavy duty tire has a tread portionwhich is divided into five inner, intermediate and outer rib-like land portions R, R, R, Rand R. The inner rib-like land portion Ris virtudally divided into half regions Rand Ron each side of a tire equator. The intermediate rib-like land portions Rand Rare virtually divided into tire equator-side half regions Rand R, and into ground-contact edge-side half regions Rand R. In a regular ground-contact state in which a normal load is applied, when total sums of ground-contact load applied to the half regions R, R, R, Rand Rare defined as P, P, P, Pand P

Heavy duty tire with tread portion having three longitudinal main grooves

In a ground-contact surface shape of a tire, when a tangent angle formed between an axial direction of the tire and a tangent X at each point P on a profile line of the tire is defined as &#x3b8;, a tangent angle &#x3b8;in a ground-contact end point Pd is 25&#xb0; or smaller. When a minimum value of the tangent angle &#x3b8; in a region Y which is separated away from a tire equator C by a distance in a range of not less than 0.4 times but not more than 0.7 times a half of the ground-contact width of the tread is defined as &#x3b8;, and a tangent angle at a 0.9 times point Pq which is separated away from the tire equator C by a distance of 0.9 times the half of the ground-contact width of the tread is defined as &#x3b8;, a difference (&#x3b8;) is set in a range of not less than &#x2212;10&#xb0; but not more than +10&#xb0;.

Heavy-duty tire having ground-contact surface shape

A pneumatic tire which comprises a tread portion with a pair of tread edges, and a tire shoulder extending radially inwardly from one of the tread edges, provided with a curved surface comprising a convex curve, wherein, on a cylindrical surface centered on the tire axis and intersecting the curved surface, the convex curve swells axially outwards and has a curvature, and the curvature gradually diminishes towards the radially inside from the tread edge. It is possible that the tread portion is provided along the tread edges with a circumferentially extending rib and/or a circumferential row of blocks. In case of circumferential rib, the rib is provided with the curved surface comprising a plurality of the convex curves and a plurality of convex curves alternating therewith so that the curved surface is waved in the tire circumferential direction. In case of blocks in a circumferential row, it is preferable that each block is provided with the curved surface comprising at last one convex curve.

Pneumatic tire having shoulder blocks with V-shaped axially inner edge and convexly curved axially outer surface

A heavy duty radial tire which is provided with traverse grooves extending between the tread edges and longitudinal grooves extending between the traverse grooves so as to form shoulder blocks arranged along each of the tread edges and inner blocks each disposed on the axially inside of one of the shoulder blocks. The longitudinal grooves between the shoulder blocks and the inner blocks have a depth Dga of 0.7 to 1.0 times the depth Dy of the traverse grooves, and the longitudinal grooves are each inclined at an acute angle with respect to the circumferential direction to have an axial extent range Y whose axial width W1 is in a range of from 1.0 to 10.0 times the width Wga. In a cross section of the tire under a normally inflated unloaded condition, the tread profile is made up of a center profile Si and a shoulder profile So. The shoulder profile So extends continuously from each of the axial ends of the center profile Si through an inflection point P to one of the tread edges. The center profile Si is a circular arc of a radius Rc having the center on the tire equatorial plane, and the shoulder profile So is a substantially straight line or alternatively an arc having less curvature than the center profile Si. The inflection point P is located within the axial extent range Y of the longitudinal grooves.

Heavy duty radial tire

A standard grounding surface shape Fbecomes a maximum grounding length Lc at a tire equator C and becomes a shortest grounding length Lm between the tire equator C and a grounding edge TE. The shortest grounding length Lm is located in a region away from the tire equator C by a distance of 0.5 to 0.9 times of a tread half width TW. A rubber thickness tbetween the carcass cord and the belt cord is gradually increased outward in the axial direction of the tire from the tire equator, and the rubber thickness tin a half width position Q which is away from the tire equator by a distance of 0.55 times of the tread half width TW is set to 0.5 to 3.0 mm. A ratio t/tbetween a tread entire thickness tin the half width position Q and a tread entire thickness tin the tire equator is set to 1.01&#xb1;0.05.

Pneumatic tire

Pneumatic tire having tire shoulder provided with curved surface

A pneumatic tire comprises a tread portion provided with a longitudinal main groove extending continuously in the tire circumferential direction and axial grooves each having at least one opening into the longitudinal main groove, and at least one of two groove walls of each of the axial grooves swells gradually towards the opening. The axial grooves include a groove having two openings and/or a groove having one opening and one closed end. The swelling part of the groove wall can be formed by a convexly curved surface extending from the tread surface towards the groove bottom, and having a single radius of curvature gradually decreasing towards the opening.

Pneumatic tire including axial grooves

A heavy duty tire comprises a pair of axially outermost circumferential rows of shoulder blocks, each of the shoulder blocks provided with a circumferentially extending narrow groove, the narrow groove subdividing the shoulder block into an axially inner wide main part and an axially outer narrow lateral part, and the narrow groove is curved convexly so that the narrow lateral part is narrower in a middle region than both the circumferential end regions, whereby the heel and toe wear and shoulder wear and resistance to tear-off can be improved.

Heavy duty tire including narrow groove

A pneumatic tire including a tread portion provided along each tread edge with a circumferential row of shoulder blocks, and each of the shoulder blocks has an axially outer side face which is convexly curved in a plane parallel to the tread surface, whereby the wandering performance of the tire can be improved without causing uneven wear, rubber tear-off, deterioration in running performance and the like.

Pneumatic tire including shoulder blocks

A pneumatic tire comprises a tread portion which is provided with a plurality of circumferential grooves extending continuously in the tire circumferential direction to axially divide the tread portion into a plurality of land portions, at least one of the land portions is provided with sipes each extending across the full width of the land portion to have a pair of open ends, each of the sipes is provided therein with at least three tie-bars to provide the bottom of the sip with at least three shallow parts in the open ends and therebetween and at least two deep parts between the shallower parts, and the depth (h2) at the shallow parts is set in the range of from 0.2 to 0.8 times the depth (h1) at the deep parts.

Growing community of inventors

Kobe, Japan

Satoshi Tsuda