A pneumatic tire includes a pair of bead portion, a pair of bead cores, a carcass extending between the pair of bead cores, and a pair of bead apex rubbers. Each bead core includes a core inner surface on an inner side in the tire radial direction of the bead core. In a pre-assemble state, each core inner surface has an angle of 20 degrees plus/minus 2 degrees to the tire axial direction, and is inclined outwardly in the tire radial direction toward an outer side in the tire axial direction. The bead apex rubber includes a first rubber portion arranged so as to cover a circumference of the bead core and having a circular or substantially elliptical outline, and a second rubber portion tapering outwardly in the tire radial direction from the first rubber portion. The first rubber portion is greater in hardness than the second rubber portion.

Provided is a heavy-duty pneumatic tire in which not only occurrence of a damage of CBU but also occurrence of pulling-out of a carcass ply can be inhibited, and which has excellent durability. In the tire, beads each include a cover enclosing at least a part of a core. The cover is located, between the core and the carcass ply, in a portion at which the carcass ply encloses the core. The cover is composed of one cover ply including a large number of aligned cover cords and a cover topping rubber covering the cover cords. A ratio of a distance between the cover cords to an outer diameter of a carcass cord is not lower than 0.35 and not higher than 0.85. A difference between a hardness of the cover topping rubber and a hardness of a carcass topping rubber is not less than −5 and not greater than 5.

A heavy truck tire is provided with a bead design that has a bead core and a reinforcement ply that wraps around a section of the bead core and has a return casing ply. Bead filler is present that has a portion radially outward from the bead core and axially inboard from the return casing ply. A stiffener layer is present that has a portion located outboard from the return casing ply. The bead has a first bead layer with a portion between the return casing ply and the stiffener layer, and a second bead layer that has a portion outboard from the stiffener layer. The stiffness of the first and second bead layers is 8 MPa to 14 MPa. The stiffness of the bead filler is less than the stiffness of the first and second bead layers.

A tire includes a carcass ply extending from one bead structure to another bead structure. Each bead structure includes a plurality of circumferentially wound sheath layers surrounding a bead core with a triangular cross-section. The cross-section has two radially inner vertices and a radially outer vertex. The radially outer vertex and one of the radially inner vertices are an angular amount radially offset from a directly radial direction of the tire.

A pneumatic tire includes a pair of bead portion, a pair of bead cores, a carcass extending between the pair of bead cores, and a pair of bead apex rubbers. Each bead core includes a core inner surface on an inner side in the tire radial direction of the bead core. In a pre-assemble state, each core inner surface has an angle of 20 degrees plus/minus 2 degrees to the tire axial direction, and is inclined outwardly in the tire radial direction toward an outer side in the tire axial direction. The bead apex rubber includes a first rubber portion arranged so as to cover a circumference of the bead core and having a circular or substantially elliptical outline, and a second rubber portion tapering outwardly in the tire radial direction from the first rubber portion. The first rubber portion is greater in hardness than the second rubber portion.

A pneumatic tire includes a pair of bead portion, a pair of bead cores, a carcass extending between the pair of bead cores, and a pair of bead apex rubbers. Each bead core includes a core inner surface on an inner side in the tire radial direction of the bead core. In a pre-assemble state, each core inner surface has an angle of 20 degrees plus/minus 2 degrees to the tire axial direction, and is inclined outwardly in the tire radial direction toward an outer side in the tire axial direction. The bead apex rubber includes a first rubber portion arranged so as to cover a circumference of the bead core and having a circular or substantially elliptical outline, and a second rubber portion tapering outwardly in the tire radial direction from the first rubber portion. The first rubber portion is greater in hardness than the second rubber portion.

A monofilament made of glass-resin composite has improved properties in compression, in particular at high temperature, and comprises glass filaments embedded in a crosslinked resin. The glass transition temperature of the resin is equal to or greater than 190° C. The elongation at break of the monofilament, measured at 23° C., is equal to or greater than 4.0%. The initial tensile modulus of the monofilament, measured at 23° C., is greater than 35 GPa. The real part of the complex modulus of the monofilament, measured at 190° C. by the DMTA method, is greater than 30 GPa. Pneumatic or non-pneumatic tires are reinforced with such a composite monofilament.

A monofilament made of glass-resin composite has improved properties in compression, in particular at high temperature, and comprises glass filaments embedded in a crosslinked resin. The glass transition temperature of the resin is equal to or greater than 190° C. The elongation at break of the monofilament, measured at 23° C., is equal to or greater than 4.0%. The initial tensile modulus of the monofilament, measured at 23° C., is greater than 35 GPa. The real part of the complex modulus of the monofilament, measured at 190° C. by the DMTA method, is greater than 30 GPa. Pneumatic or non-pneumatic tires are reinforced with such a composite monofilament.

Provided is a pneumatic tire. A carcass line when 10% of a regular internal pressure is applied is composed of a curved line (S) connecting arcs having different radii of curvature and curved to project outward in a tire width direction and a curved line (T) curved to project inward in the tire width direction. A radius of curvature (R.sub.i) at a point on the curved line (S) and a radius of curvature (R.sub.i+1) at an adjacent point satisfy |R.sub.i+1−R.sub.i|/|(R.sub.i+1+R.sub.i)/2|≤0.25. An inclination (θ.sub.S) and an inclination (θ.sub.T) at a connection point (Q) of the curved line (S) and the curved line (T) satisfy |θ.sub.S−θ.sub.T|8°. A ratio (Hβ/Hα) between a radial height (Hα) at a maximum outer diameter position of a carcass layer and a radial height (Hβ) at a tire maximum width position satisfies Hβ/Hα ≥0.58.

Provided is a pneumatic tire. A carcass line when 10% of a regular internal pressure is applied is composed of a curved line (S) connecting arcs having different radii of curvature and curved to project outward in a tire width direction and a curved line (T) curved to project inward in the tire width direction. A radius of curvature (R.sub.i) at a point on the curved line (S) and a radius of curvature (R.sub.i+1) at an adjacent point satisfy |R.sub.i+1−R.sub.i|/|(R.sub.i+1+R.sub.i)/2|≤0.25. An inclination (θ.sub.S) and an inclination (θ.sub.T) at a connection point (Q) of the curved line (S) and the curved line (T) satisfy |θ.sub.S−θ.sub.T|8°. A ratio (Hβ/Hα) between a radial height (Hα) at a maximum outer diameter position of a carcass layer and a radial height (Hβ) at a tire maximum width position satisfies Hβ/Hα ≥0.58.