Abstract: A heavy-duty pneumatic tire comprises: a carcass ply turned up around a bead core in each bead portion from the inside to the outside of the tire so as to have a pair of turnup portions and a main portion therebetween; and a bead apex and an L-shaped reinforcing cord layer which are disposed in each of the bead portions. The bead apex includes: an L-shaped high-modulus inner bead apex; and a delta-shaped low-modulus outer bead apex. The L-shaped inner bead apex comprises: a base part along a radially outer surface of the bead core; and a radial part along the carcass ply main portion. The delta-shaped outer bead apex is disposed on the radially outside of the base part of the L-shaped inner bead apex and on the axially outside of the radial part of the L-shaped inner bead apex. The L-shaped reinforcing cord layer is made up of an radially inner part extending on the radially inner side of the bead core, and an radially outer part extending along the axially outer surface of the carcass ply turnup portion.

Abstract: A heavy duty tire having an improved durability in bead portions and comprising a carcass ply of steel cords, the end portions of which are turned up around bead cores from the axially inside to the axially outside of the tire, and a core protecting rubber having a complex elastic modulus of 50 to 80 Mpa, at least a part of which is located in a core inside region which is located axially inward of the bead core and is sandwiched between the axially inner surface of the bead core and the steel cords of the turnup portion of the carcass ply.

Abstract: A heavy duty tire has a tread portion 2 which is divided into five inner, intermediate and outer rib-like land portions R1, R2, R2, R3 and R3. The inner rib-like land portion R1 is virtudally divided into half regions R1a and R1a on each side of a tire equator. The intermediate rib-like land portions R2 and R3 are virtually divided into tire equator-side half regions R2c and R3c, and into ground-contact edge-side half regions R2e and R3e. 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 R1a, R2c, R2e, R3c and R3e are defined as P1a, P2c, P2e, P3c and P3e, P2c/P1a is set to 0.9 to 1.05, P2e/P2c is set to 0.75 to 1.0, P3c/P2e is set to 0.9 to 1.2, and P3e/P3c is set to 0.8 to 1.1.

Abstract: The present invention relates to a heavy duty tire being capable of preventing positional shift of carcass cords in the blowout direction while restricting rupture of the carcass cords for improving bead durability. A ply turnup portions 6b of a carcass 6 includes a sub-portion 11 that extends proximate of an upper surface SU of a bead core 5 in a tire radial direction upon inclining towards a ply main body portion 6a and further includes an auxiliary cord layer 20 for pressing the sub-portion outside thereof in the radial direction. A bead portion 4 is further provided with a U-shaped bead reinforcing layer 15. A periphery of the bead core 5 is coated by a reinforcing rubber layer 15 made of high elastic rubber having a complex elastic modulus E*a of 20 to 70 MPa, and a rubber thickness T0 of a clearance portion G at which bead wires 5w and carcass cords 20 are adjacent is defined to be not less than 0.

Abstract: A heavy duty tire comprises: a bead filler disposed radially outside a bead core and axially outside a carcass main portion; a bead-reinforcing layer made of steel cords; and a chafer made of a rubber extending along the bead bottom surface. The chafer rubber has a complex elastic modulus in a range of 8 to 12 MPa and a 100% modulus in a range of 4.0 to 5.5 MPa. In the bead-reinforcing layer, the steel cord count is 25 to 40/5 cm, the steel cord diameter is 0.8 to 1.2 mm, and the cord angle is 30 to 60 degrees with respect to the tire radial direction. The bead filler comprises a main filler made of a low modulus rubber and a fastening filler made of a high modulus rubber. The fastening filler has an L-shaped cross sectional shape and comprises an axially-extending base portion and a radially-extending axially inner portion. The main filler has a part wedged between the base portion and axially inner portion of the fastening filler.

Abstract: A heavy duty tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions each with a bead core therein, the bead core with an aspect ratio (HC1/WC) of from 0.43 to 0.58, and a carcass comprising a carcass ply of cords extending between the bead portions and turned up around a bead core in each bead portion from the inside to outside of the tire so as to form a pair of turnup portions and a main portion therebetween, the turnup portion comprising a turnup main-part extending along an axially inner surface, a radially inner surface and an axially outer surface of the bead core smoothly, and a turnup sub-part extending from the turnup main-part toward the main portion near the radially outer surface of the bead core.

Abstract: A heavy duty tire having a bead wind structure and comprising a bead reinforcing layer 15 having a U-shaped cross section disposed in each bead portion 4, wherein the axially outer portion 15o of the bead reinforcing layer 15 and its radially outer end Pe are protected by an axially inner rubber 20 disposed between the carcass main portion 6a and the outer portion 15o and an axially outer rubber 30 disposed between the outer portion 15o and the axially outer surface TS of the tire, in which the inner rubber 20 includes a first low modulus rubber portion 21 having a complex elastic modulus of 3.0 to 6.0 MPa, the thickness Ti of the inner rubber 20 measured on a first base line X1 drawn from the radially outer end Pe at right angles to the carcass main portion 6a is from 7.0 to 13.0 mm and the ti/Ti ratio of a thickness ti of the first low modulus rubber portion 21 on the first base line X1 to the thickness Ti is at least 0.

Abstract: A heavy-load tire has a wind bead structure in which a turned-up portion of a carcass ply is wound around a bead core, in which a bead portion is equipped with a bead reinforcing layer having a U-shaped cross section and a bead apex rubber having a triangular-shaped cross section. The turned-up portion has an auxiliary turned-up portion passing through the vicinity of a radially outer side of the bead core. The bead apex rubber includes a high elasticity inner apex portion disposed at a radially inner side and a low elasticity outer apex portion disposed at a radially outer side. The inner apex portion has an L-shaped cross section including a bottom piece portion along the radially outer side of the auxiliary turned-up portion, and a raised piece portion which rises at an axially inner end side of the bottom piece portion and extends radially outwardly in a tapering manner along the body portion of the carcass ply.

Abstract: A heavy duty tire comprises: a carcass ply of cords extending between bead portions; and a bead reinforcing layer disposed in each of the bead portion. The carcass ply has edges winded around the bead cores so that the winded portion has a base part extending along the bead core from the axially inside to the axially outside thereof, and a radially outer part extending axially inwards on the radially outside of the bead core. The bead reinforcing layer comprises: a curved portion extending along the base part; an axially outer portion extending radially outwardly, separation from the base part; and an axially inner portion extending radially outwardly along a main portion of the carcass ply. The bead reinforcing layer is composed of a ply of cords laid side by side, and the spacing Da of the cords in an axially outer part beneath the bead core, of the curved portion is not less than 1.5 times and not more than 3.0 times the spacing Db of the cords in the axially outer portion.

Abstract: A heavy duty tire comprises a bead filler disposed in each bead portion (4). The bead filler (8) comprises: a main layer (13) having a complex elastic modulus E*2 of from 2.0 to 6.0 Mpa; and a fastening layer (12) having a complex elastic modulus E*1 of from 20 to 70 Mpa. The fastening layer comprises a base portion (12B) and an axially inner portion (12A) to have a L-shaped cross section. The height Ha of the axially inner portion (12A) is 35 to 100 mm and not more than the height Hb of the main layer (13), and the radial height Hb is 40 to 100 mm, each from the bead base line.

Abstract: A pneumatic tire 1 having improved uniformity and durability and including a toroidal carcass 6 extending from a tread portion 2 to each of bead cores 5 in bead portions 4 through sidewall portions 3, a belt layer 7 disposed radially outward of the carcass 6 in the tread portion 2, and a cushion rubber 9 having an approximately triangular cross section disposed between the carcass 6 and each of axial edge portions 7E of the belt layer 7, and a method for producing the same, wherein the cushion rubber 9 is made from a strip laminated body formed by circumferentially and spirally winding a first ribbon-like unvulcanized rubber strip and a second ribbon-like unvulcanized rubber strip having a different composition from that of the first rubber strip.

Abstract: A heavy duty tire having a bead wind structure and comprising a bead reinforcing layer 15 having a U-shaped cross section disposed in each bead portion 4, wherein the axially outer portion 15o of the bead reinforcing layer 15 and its radially outer end Pe are protected by an axially inner rubber 20 disposed between the carcass main portion 6aand the outer portion 15o and an axially outer rubber 30 disposed between the outer portion 15o and the axially outer surface TS of the tire, in which the inner rubber 20 includes a first low modulus rubber portion 21 having a complex elastic modulus of 3.0 to 6.0 MPa, the thickness Ti of the inner rubber 20 measured on a first base line X1 drawn from the radially outer end Pe at right angles to the carcass main portion 6a is from 7.0 to 13.0 mm and the ti/Ti ratio of a thickness ti of the first low modulus rubber portion 21 on the first base line X1 to the thickness Ti is at least 0.

Abstract: A pneumatic tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions with a bead core therein, and a carcass ply extending between the bead portions through the tread portion and sidewall portions and wound around the bead core in each of the bead portions from the axially inside to the axially outside of the tire so as to form a pair of wound portions and a main portion therebetween, wherein the bead core has a cross sectional shape elongated in a direction substantially parallel to the bottom of the bead portion so that the width (WC) thereof measured in this direction is in a range of from 1.5 to 2.5 times the height (HC) thereof measured perpendicularly thereto, and the bead core is covered with a high modulus rubber layer having a complex elastic modulus E*1 of from 20 to 100 Mpa and a thickness t1 of from 0.5 to 3.0 mm.

Abstract: The present invention relates to a heavy duty tire comprising a carcass comprising a carcass ply of cords extending between bead portions and turned up around a bead core in each bead portion from the inside to outside of the tire so as to form a pair of turnup portions and a main portion therebetween, and a bead reinforcing layer comprising at least one reinforcing ply of cords disposed of each said bead portion, wherein the turnup portion comprises a turnup main part extending an inner region inside a extension line obtained by extending a radially outer surface of the bead core, and a turnup sub part extending an outer region outside said extension line through a portion near the radially outer surface of said bead core, and wherein the reinforcing cord ply comprises a center portion extending along the radially inside the turnup main part, an axially outside portion extending from the center portion to the radially outside of the tire apart from said turnup portion, and an axially inside portion extend

Abstract: A heavy duty tire comprises bead portions (4) each with a bead core (5), and a carcass ply (6A) comprising a main portion (6a) extending between bead portions and a pair of edge portions (6b) winded around the bead cores (5), the winded edge portion (6b) comprises a turnback part (11) extending axially inwardly from a position (P0) on the axially outside of the bead core (5), an auxiliary cord layer (8) is disposed on the radially outside of the turnback part (11), whereby the end (11e) of the turnback part (11) is positioned at a distance (u1) of from 2.0 to 8.0 mm from the radially outer surface (su) of the bead core. In a normally inflated unloaded state of the tire, the turnback part (11) is curved such that the diameter of the turnback part (11) decreases continuously from the end (11e) to the position (P0).

Abstract: A heavy duty tire having an improved durability in bead portions and comprising a carcass ply of steel cords, the end portions of which are turned up around bead cores from the axially inside to the axially outside of the tire, and a core protecting rubber having a complex elastic modulus of 50 to 80 Mpa, at least a part of which is located in a core inside region which is located axially inward of the bead core and is sandwiched between the axially inner surface of the bead core and the steel cords of the turnup portion of the carcass ply.

Abstract: A heavy duty tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions each with a bead core therein, the bead core with an aspect ratio (HC1/WC) of from 0.43 to 0.58, and a carcass comprising a carcass ply of cords extending between the bead portions and turned up around a bead core in each bead portion from the inside to outside of the tire so as to form a pair of turnup portions and a main portion therebetween, the turnup portion comprising a turnup main-part extending along an axially inner surface, a radially inner surface and an axially outer surface of the bead core smoothly, and a turnup sub-part extending from the turnup main-part toward the main portion near the radially outer surface of the bead core.

Abstract: The present invention relates to a heavy duty tire being capable of preventing positional shift of carcass cords in the blowout direction while restricting rupture of the carcass cords for improving bead durability. A ply turnup portions 6b of a carcass 6 includes a sub-portion 11 that extends proximate of an upper surface SU of a bead core 5 in a tire radial direction upon inclining towards a ply main body portion 6a and further includes an auxiliary cord layer 20 for pressing the sub-portion outside thereof in the radial direction. A bead portion 4 is further provided with a U-shaped bead reinforcing layer 15. A periphery of the bead core 5 is coated by a reinforcing rubber layer 15 made of high elastic rubber having a complex elastic modulus E*a of 20 to 70 MPa, and a rubber thickness T0 of a clearance portion G at which bead wires 5w and carcass cords 20 are adjacent is defined to be not less than 0.

Abstract: A standard grounding surface shape F0 becomes 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 t1 between 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 t1 in 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 t2q/t2c between a tread entire thickness t2c in the half width position Q and a tread entire thickness t2c in the tire equator is set to 1.01±0.05.

Abstract: A viscoelastic characteristic value-measuring apparatus, using a split Hopkinson's bar, having an impact bar, input bar, and an output bar. The input bar has a first strain gauge and a second strain gauge. The output bar has a third strain gauge and a fourth strain gauge. The input bar and the output bar are made of a viscoelastic material, and a specimen is in between the input bar and the output bar. The length of said output bar is set to a range from 500 mm to 2500 mm both inclusive. The length of said input bar is set to a range from 1500 mm to 2500 mm both inclusive.