Sumitomo Rubber Industries Limited

Kazuki Numata

Kiyoshi Ueyoko

Tsuneyuki Nakagawa

Yukio Endo

Ikuji Ikeda

Yoshio Ohara

Kiyoshi Ochiai

Shinichi Miyazaki

Masaki Shiraishi

Minoru Nishi

Shuichi Sakamoto

Kenji Asano

A heavy duty tire includes, in a tread portion, circumferentially extending zigzag center main grooves, circumferentially extending linear shoulder main grooves, a center land portion, middle land portions, and shoulder land portions. The middle land portions have middle inclined grooves connecting an axially outer top portion of one of the center main grooves and its adjacent shoulder main groove. The shoulder land portions have shoulder inclined grooves connecting one of the shoulder main grooves and its adjacent tread grounding end. The center land portion has first center inclined sipes connecting an axially inner top portion of one of the center main grooves and its adjacent axially inner top portion of the other center main groove and second center inclined sipes connecting an axially outer top portion of one of the center main grooves and its adjacent axially outer top portion of the other center main groove.

Heavy duty tire

A pneumatic tire has an asymmetrical tread pattern. An outboard central main circumferential groove extends zigzag and is made up of alternate minor and major groove segments. The major groove segments incline at an angle of from 5 to 30 degrees with respect to the tire circumferential direction. An inboard central main circumferential groove is widest in main circumferential grooves. Outboard middle axial grooves are widest in axial grooves. The distance Li of the widthwise center line of the straight inboard central main circumferential groove from the tire equator is less than the distance Lo of the amplitude center line of the zigzag outboard central main circumferential groove from the tire equator.

Pneumatic tire

A pneumatic tire provided with a tread pattern, wherein a tread half which is one half of the tread pattern on each side of the tire equator is made up of repeat design units arranged circumferentially of the tire. The repeat design units have at least two different circumferential pitch lengths, and the repeat design units are each provided with at least one stud hole.

A pneumatic tire () provided in the tread portion () with a row (R) of crown blocks () divided by crown axial grooves (), two rows (R) of middle blocks () divided by middle axial grooves (), and two rows (R) of shoulder blocks () divided by shoulder axial grooves (), Each of the crown axial grooves () is circumferentially aligned with one of the middle axial grooves () such that the crown axial groove () is positioned within a middle-axial-groove range (Mc) defined between 1st and 2nd axial straight lines (Za and Zb) which are drawn passing through 1st and 2nd extreme circumferential end points (and) of the middle axial groove (), respectively. The circumferential length of the middle-axial-groove range (Mc) is not less than 25% but not more than 50% of a pitch length (P) defined between the two 1st extreme circumferential end points (and). The middle-axial-groove range (Mc) does not overlap with any of the shoulder axial grooves ().

A heavy duty tire having both an excellent wear resistance and a low rolling resistance and comprising a tread rubber having a two layer structure composed of a cap rubber layerGb and a base rubber layerGa underlying the cap layer, wherein the tread rubber extends axially outward from the tire equator and is bent at its edges to extend radially downward so that the cap layer is located axially outward of the base layer, and a pair of sidewall rubbers are disposed so that the radially outer end portion of each sidewall rubber covers the surface of the axially outer end of the tread rubber.

Heavy duty tire having cap and base rubber layers, belt cushion rubber and sidewall rubber

A heavy duty tire with decreased rolling resistance without impairing durability, comprising carcass, belt layerdisposed radially outward of the carcass in tread portion, and sidewall rubberdisposed axially outward of the carcass in sidewall portionand extending in the radial direction of the tire, wherein the sidewall rubber includes an axially inner rubber portiondisposed axially outward of the carcass and an axially outer rubber portiondisposed axially outward of the inner rubber portion to form the tire outer surface, the inner rubber portionhas a lower loss tangent 'tan &#x3b4;' than the outer rubber portionby a difference of 0.010 to 0.035, and the inner rubber portionhas a lower complex elastic modulus than the outer rubber portionby a difference of 0.5 to 1.4 MPa.

A pneumatic tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions, a bead core disposed in each bead portion, a carcass comprising a ply of carcass cords extending between the bead portions through the tread portion and sidewall portions and turned up around the bead core in each bead portion, and an inner liner made of air-impermeable rubber extending on the tire cavity side of the carcass from one of the bead portions to the other. The radially inner end of the inner liner is located radially inside the radially innermost end of the carcass. In a radial region between the radially innermost end of the carcass and the radially outermost end of the bead core, the thickness of the inner liner is not less than 0.15 time but not more than 4.0 times the cross section diameter of the carcass cord.

Pneumatic tire with specified inner liner

A pneumatic tire comprises a pair of bead portions each provided therein with a bead core made of windings of at least one wire, a carcass ply of cords extending between the bead portions and turned up around the bead core from the axially inside to the outside of the tire to form a pair of turnup portions and a main portion therebetween, a rubber bead apex disposed radially outside the bead core and between each said turnup portion and the main portion, and a fiber reinforced rubber spacer interposed between the bead core and the carcass ply to provide a positive distance between the carcass ply cords and bead core wire. The fiber reinforced rubber spacer has a securing portion which extends radially outwardly and axially outwardly from the axially inside of the bead core while separating from the bead core but contacting with the rubber bead apex. A distance (L , L ) between an outermost point of the securing portion and the bead core is in a range of from to times a height of the bead core.

A pneumatic tire comprises a carcass ply extending between bead portions and is turned up around a bead core in each bead portion to form two turnup portions and a main portion therebetween; each of the turnup portion extends radially outwardly and adjoins the main portion from a certain height above the bead core; a space is surrounded by the carcass ply main portion, and each turnup portion and the bead core is filled with a small size bead apex rubber or a gas; and the bead portion is provided between the carcass ply and the bead core with a bead core cover for preventing the carcass cords from direct contacting with the bead core.

Pneumatic tire with specified bead portion

A heavy duty radial tire has a carcass including a carcass ply made of cords arranged at an inclination angle of 70 to 90 degrees with respect to the tire equator, the carcass ply including a main portion extending from a tread portion to a bead core in a bead portion and integrally provided with a turnup portion turned up from the axially inside to the outside at the bead core, a bead apex disposed between the main portion and turnup portion of the carcass ply, wherein the turnup portion extends radially outwardly along the axially outer surface of the bead apex and has a portion extending substantially parallel with and adjacent to the carcass ply main portion from the radially outer end of the bead apex, and the length L of the parallel portion is 1.0 to 8.0 times the maximum section width CW of the bead core.

Heavy load radial tire with specified carcass turnup

A pneumatic tire comprises a carcass ply extending between bead portions and is turned up around a bead core in each bead portion to form two turnup portions and a main portion therebetween; each of the turnup portions extends radially outwardly and adjoins the main portion from a certain height above the bead core; a space is surrounded by the carcass ply main portion, and each turnup portion and the bead core is filled with a small size bead apex rubber or a gas; and the bead portion is provided between the carcass ply and the bead core with a bead core cover for preventing the carcass cords from direct contacting with the bead core.

A pneumatic tire comprises a breaker disposed radially outside a carcass and having a cord angle of not less than 10 degrees, and a band disposed between the carcass and the breaker and having a cord angle of less than 10 degrees, the breaker having a double-layered cord structure comprising a radially outer layer and a radially inner layer between which the cord inclination is reversed, the band being made of spiral windings of at least one cord; and the breaker is preferably formed by continuously winding at least one cord zigzag around the radially outside of the band plural times, in each turn the tape being bent at the axial edges of the breaker.

Pneumatic tire with band between carcass and breaker

A heavy duty radial tire is to be mounted on a 15 degree drop center rim. In a mounted state that the tire is mounted on the rim and inflated to 0.5 ksc but not loaded, the inside diameter BC of the bead cores at the radially innermost point thereof is set to being not more than the diameter BT at the heel point of the bead portions. In a demounted state that the tire is demounted from a rim, the bead bottom is tapered towards the axial inside of the tire at an angle .theta. of from 1.0 to 1.9 times the angle .alpha. of the tapered bead seat of the rim. In the mounted state, the bead core has a radially inner surface tapered at the substantially same angle as the bead seat, and the axial distance BP of the axially inner end of this tapered inner surface from the bead heel point is set in the range of from 1.3 to 2.1 times the maximum width BW of the bead core measured in the direction parallel to the bead seat. A straight line drawn between a point P2 at which the carcass main portion starts to contact the bead core and a point P3 at which the carcass main portion and a radially extending straight line passing the axially inner end of the radially inner surface of the bead core intersect each other, is inclined at angle .beta. of from 45 to 60 degrees with respect to the tire axial direction.

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Kobe, Japan

Kazuki Numata