A pneumatic tire containing a polyester (e.g., polyethylene terephthalate or polyethylene naphthalate) derived from a non-fossil raw material. In a preferred embodiment, a polyester (e.g., polyethylene terephthalate or polyethylene naphthalate) in which a linear or cyclic moiety is produced using a raw material derived from a non-fossil raw material is used in the pneumatic tire. A pneumatic tire in which polyethylene terephthalate or polyethylene naphthalate produced using a raw material derived from a non-fossil raw material is used as a carcass material or a belt reinforcing material.

In a pneumatic tire, a carcass layer mounted between bead portions includes composite cords made of polyethylene terephthalate fiber yarn having a fineness from 420-1200 dtex and an aromatic polyamide fiber yarn having a fineness from 520-1200 dtex, and a total fineness from 940-2400 dtex, and a twist coefficient from 1600 to 2400, the composite cords having an intermediate elongation from 2.0% to 4.5% with a load of 2.0 cN, having a dimensional stability index from 2.5% to 6.0% which is a sum of a dry heat shrinkage rate at 150 C. and the intermediate elongation with the load of 2.0 cN, and having a ratio of an initial elastic modulus at 100 C. within a load range from 0 N to 44 N with respect to an initial elastic modulus at 25 C. within a load range from 0 N to 44 N, the ratio being from 76% to 94%.

Provided are a pneumatic tire with improved dimensional stability, low loss property, and durability and a method of producing the same. In a pneumatic tire, a rubber-fiber composite is used in at least any of a carcass ply and a cap ply, the rubber-fiber composite containing: a fiber cord made of polyamide multifilament fibers having a glass transition temperature in a range of 150 C. to 200 C.; and a rubber, a layer made of a resorcin-formalin-latex adhesive is formed at an interface between the fiber cord and the rubber, and a thermal contraction stress at 177 C. of the fiber cord with the layer formed thereon is 0.01 cN/dtex to 0.2 cN/dtex.

In a pneumatic tire including a carcass layer mounted between a pair of bead portions and a belt reinforcing layer disposed on an outer circumferential side of the carcass layer, the carcass layer is formed of a carcass cord made of an organic fiber cord, an elongation at break of the carcass cord is set to 20% or more, an elongation under a load of 1.5 cN/dtex of the carcass cord on the inner circumferential side of the belt layers is set to from 5.5% to 8.5%, the belt reinforcing layer is formed of a cover cord made of an organic fiber cord, and a tensile strength of the cover cord per width of 50 mm at a 3.0% elongation is set to from 2.8 kN to 4.0 kN.

A pneumatic tire to reduce separation of a carcass ply from inner and outer core pieces (5i, 5o) and improve steering stability. A radially inner end portion of the carcass ply is held between the inner and outer core pieces (5i, 5o) without turning-up around a bead core. The inner and outer core pieces (5i, 5o) are made of helical body of bead cord (10i, 10o) helically winding around a tire axis. In the inner core piece (5i), the final twisting direction of the bead cord (10i) is the same as the winding direction around the tire axis of the bead cord (10i) in side view from axial outward of the tire. In the outer core piece (5o), the final twisting direction of the bead cord (10o) is opposite to the winding direction of the bead cord (10o).

A run flat tire 1 comprises a carcass 6 formed of a carcass ply 6A extending between a pair of bead portions 4 in a toroidal manner and a side reinforcing rubber layer 9 having a substantially crescent cross-sectional shape disposed on an inner side of the carcass at each of sidewall portions. steel cords 60 each including 1 to 4 filaments 61 having a strand diameter in a range of from 0.25 to 0.30 mm are arranged in the carcass ply 6A, and an outer diameter D of each of the steel cords 60 is not less than 0.62 mm.

In a tire having a cross-sectional height from 50-150 mm, in an unloaded state mounted on a specified rim and inflated to a specified internal pressure, a distance (A) between the tire and a rim flange on a perpendicular line drawn from a rim flange outermost point in a radial direction to a tire outer surface with respect to the cross-sectional height (SH) satisfies 0.01?A/SH?0.16, and a point (S) where the rim flange separates from the tire is defined, a point (T) where the perpendicular line drawn from the rim flange outermost point in the radial direction to the tire outer surface intersects the tire outer surface is defined, two perpendicular lines are drawn from (S) and (T) to a carcass layer turned-up portion, and a cross-sectional area (Sr) of a rubber portion in a region surrounded by the two perpendicular lines and the carcass layer turned-up portion satisfies 12 mm.sup.2?Sr?101 mm.sup.2.

The reinforcing structure for a tire is in the form of a stratified assembly formed of two layers of reinforcing strips of completely connected cross section, and flattened in shape. According to the method, the strips of each layer are laid side by side in a main direction of laying. The strips of the first layer are spaced apart by a distance that is less than the width of the strips of the second layer and in such a way that the edges of the strips of the first layer overlap the edges of the strips of the second layer. The two layers of strips are separated by a layer of uncoupling rubber.

A tire having a radial carcass reinforcement, composed of at least one layer of metal reinforcing elements, the said tire comprising a crown reinforcement, itself topped radially by a tread, the said tread being joined to two beads via two sidewalls. The metal reinforcing elements of at least one layer of the carcass reinforcement are cords exhibiting, in the permeability test, a flow rate of less than 20 cm.sup.3/min and at least one layer of the carcass reinforcement is provided, on at least one face, with textile threads exhibiting, in the permeability test, a flow rate of between 1 and 3 cm.sup.3/min.

The present invention provides a tire improved in the run flat durability, having at least one member selected from the group consisting of a side reinforcing rubber layer and a bead filler using a rubber composition comprising a rubber component containing 20% by mass or more of a modified conjugated diene based polymer, satisfying Expression (1) in terms of the elongation X under a stress of 6.5 MPa at 180 C. and the elongation Y under a stress of 6.5 MPa at 25 C. after vulcanization.

1.00X/Y1.15 (1)