Abstract: A heavy-duty radial tire having a belt layer comprising at least four metallic cord layers of first, second, third, and fourth belts in that order from the carcass layer towards the tread. The first belt has a cord angle of 40.degree. to 75.degree. relative to the circumferential direction of the tire and is split into left and right portions provided on left and right shoulder portions, respectively, so as to provide a space in the central region of a crown portion provided with either at least one organic fiber cord layer having a total tensile strength per unit width of at least 240 kgf/cm and a cord angle of 0.degree. to 10.degree. or an inextensible fiber cord layer having a two-layer structure wherein the sum of the tensile moduli per unit width in the initial tension of all the cords is at least 1.3.times.10.sup.3 kgf/cm, the cord angle is larger than 0.degree. and two layers in the two-layer structure cross each other at an absolute angle smaller than the cord angle of the second and third belts.

Abstract: An improvement in the structure of the belt portion of a heavy duty radial tire for use in trucks, large-size buses, small-sized trucks, etc., and more particularly, a heavy duty pneumatic radial tire improved with respect to the driving stability under heavy duty conditions while ensuring the durability of the tire (belt portion) during high speed running through the provision of at least three belt layers between the tread surface and the carcass layer of the tire and the specification of the relationships between the angles of the cords constituting these plurality of belt layers.

Abstract: An pneumatic radial tire for a passenger car having an improved durability, which tire has a carcass layer formed of aromatic plyamide cords in which an end portion of the carcass layer is turned up around an annular bead wire and a lower bead filler from the inside to the outside of the tire to form a turnup portion which is extended along the main body of the carcass layer, wherein an upper bead filler having a JIS hardness of from 75 to 95 is disposed axially outside the turnup portion, and wherein the height b (mm) of the lower bead filler relative to the height a (mm) of a rim flange upon which the tire is mounted satisfies the formula:(a-5)<b<(a+10)wherein a is the G dimension specified by JIS-D-4218-1981.

Abstract: A pneumatic tire is improved by use of carcass cords being made from aromatic polyamide fiber and having a twisting angle of 31.3 to 39.3 degree. Durability is much improved.

Abstract: A heavy load radial tire is disclosed, wherein a sub-carcass layer having a cord angle substantially equal to that of a carcass layer is disposed on the carcass layer, and at least one belt layer whose cords cross at right angles the cords of the sub-carcass layer is disposed on the sub-carcass layer.

Abstract: A pneumatic radial passenger-car tire comprising a carbon fiber cord layer disposed between a carcass layer on the side of an inner liner and a bead filler all along the circumference of the tire, and having a height thereof between a bead heel and the top end thereof equal to or larger than the height of the bead filler between the bead heel and the top end thereof.

Abstract: A heavy duty pneumatic radial tire,wherein a main area of contact with the road provided on a tread surface is formed with a circular arc, having a large radius of curvature, which crosses another circular arc having a small radius of curvature, Ra, to form an edge-shaped boundary, said radius of curvature, Ra, being larger than the depth of main grooves provided in said main area of contact with the road and smaller than the value five times as much as the depth of said main grooves,wherein narrow grooves provided on the shoulder portions are linearly provided in the circumferential direction of the tire and at a distance of 1.5 to 5 mm away towards the center of the tread surface from said edge-shaped boundary and have a groove width in the range of 1.5 to 5 mm, the direction of said narrow groove being inclined at an angle in the range of 1.degree. to 5.degree.

Abstract: In a pneumatic tire of a structure in which a belt-reinforcing layer is overlaid and interposed between a tread and a carcass cord layer, the belt-reinforcing layer consisting of a transient-reinforcing layer positioned in contact with the carcass cord layer with its reinforcing cords disposed at an angle of between 40.degree. to 75.degree. with respect to the circumferential direction of the tire, and at least two belt-resistant layers, the lower one thereof being laid over the transient-reinforcing layer with its reinforcing cords disposed at an angle of between 15.degree. to 30.degree. with respect to the circumferential direction of the tire, and the upper one with its reinforcing cords disposed at an angle of between 150.degree. to 165.degree. thereto, the tire is improved in that the carcass cord layer is formed of a single layer and the reinforcing cords in the carcass cord layer are arranged so that their angle with respect to the circumferential direction of the tire is between 75.degree. to 85.

Abstract: In a pneumatic tire of the type which consists of a pair of right and left beads; a pair of right and left side walls continuing the beads, respectively, and a tread interposed between the side walls, and in which a carcass cord layer is spread between the beads, and at least two layers consisting of a belt reinforcing layer whose reinforcing cords have a cord angle of from 15.degree. to 30.degree. with respect to the circumferential direction of the tire and a belt reinforcing layer whose reinforcing cords have a cord angle of from 150.degree. to 165.degree.

Abstract: Disclosed herein is a pneumatic radial tire for a passenger car wherein, among a plurality of belt layers, a belt layer or layers consisting of aromatic polyamide fiber cords are disposed on the side of a carcass layer, a belt layer or layers consisting of carbon fiber cords are disposed on the side of a tread portion in the proximity of the belt layer on the carcass layer side, the end portions of at least one of the belt layers on the carcass layer side, consisting of the aromatic polyamide fiber cords, are bent towards the tread portion so that the bent portions cover the end portions of the belt layer on the tread portion side, consisting of the carbon fiber cords.

Abstract: A pneumatic radial tire comprises (1) a pair of left and right bead portions, (2) a pair of left and right side-wall portions continuing from the respective bead portions, (3) a tread portion positioned between the side-wall portions, (4) a carcass layer provided between the left and right bead portions a cord angle of which is substantially 90 degree in relation to the circumferential direction of the tire, (5) an auxiliary carcass layer a cord angle of which is substantially 0 degree in relation to the circumferential direction of the tire, being placed on the tread side of the carcass layer substantially to correspond to the tread portion, so that the carcass layer and the auxiliary carcass layer may be crossed substantially at a right angle to form a net structure, and (6) a belt reinforcement layer having a tensile ridigity, at the circumferential of the tire, of not less than 10 kg/mm2, being placed on the auxiliary carcass layer substantially to correspond to the tread portion.

Abstract: A pneumatic tire of which the durability of the turnup portions of a carcass layer is greatly improved. The tire consists of left and right bead portions, left and right side wall portions continuing from the bead portions, a tread positioned between the side wall portions, a carcass layer provided between the left and right bead portions so that a cord angle with respect to the circumferential direction the tire is 70.degree.-90.degree., and a belt reinforcement layer provided between the tread and carcass layer, characterized in that the carcass layer is formed by burying 20-60 aromatic polyamide fiber cords of 0.55-0.65 mm in diameter per 5 cm of the carcass layer in an equatorial plane in the tire in rubber coats of which a 100% modulus is 30-70 kg/cm.sup.2.

Abstract: A pneumatic tire having on its tread surface a tread pattern formed by grooves and having a tread rubber of a two-layer structure comprising a cap rubber layer and a base rubber layer of which the latter comprises a rubber having a lower heat generating characteristic in comparison to a rubber forming the former, the tire being characterized by having a value within the range of from 0.15 to 0.35 for (Gc/G).times.(Eb/Ec), in which G is the total thickness of the tread rubber at the bottom of grooves in the tread pattern, Gc being the thickness of the cap rubber at the bottom of the tread pattern groove, Eb being the modulus at 25% elongation of the base rubber layer, Ec being the comparable modulus of the rubber of the cap rubber layer.

Abstract: A pneumatic radial tire for passenger vehicles, having a belt reinforcement layer consisting of a steel cord layer and a layer of aromatic polyamide fiber cords having its side ends bent over toward each other, wherein the layer of aromatic polyamide fiber cords is formed by embedding in covering rubber of a 100% modulus of 30 to 70 kg/cm.sup.2, 40 to 70 parallel aromatic polyamide fiber cords of 0.55 to 0.65 mm in diameter per 5 cm distance in the direction at right angle to the lengthwise direction of these cords.

Abstract: In a pneumatic tire of the type which consists of a pair of right and left beads, a pair of right and left side walls continuing the beads, respectively, and a tread interposed between the side walls, and in which a carcass cord layer is spread between the beads, and at least two layers consisting of a belt reinforcing layer whose reinforcing cords have a cord angle of from 15.degree. to 30.degree. with respect to the circumferential direction of the tire and a belt reinforcing layer whose reinforcing cords have a cord angle of from 150.degree. to 165.degree.

Abstract: This pneumatic tire is of the type in which two belt-reinforcing layers crossing each other and at an angle of 15.degree. to 30.degree. with respect to the circumferential direction of the tire are laid over each other and over a carcass cord layer of a tread portion. The improvement lies in that the carcass cord layer consists of upper and lower layers; the lower carcass cord layer continues in its widthways direction so that each of its edges is turned up around one of a pair of right and left bead wires, respectively; the upper carcass cord layer has a split structure so that it is separated to the right and left at the tread portion; the edge portions of the upper carcass cord layer nearer the tread portion overlaps the belt-reinforcing layer to a width of at least 10 mm while the edge portions thereof nearer the bead portions are at a height of not more than 0.

Abstract: A pneumatic tire is disclosed which comprises a tread, a carcass cord layer and at least two belt reinforcing layers disposed between the tread and the carcass cord layer, wherein the reinforcing cord of one of the belt reinforcing layers has an angle of 15.degree. to 30.degree. with respect to the circumferential direction of the tire and the reinforcing cord of the other makes an angle of 150.degree. to 165.degree. to the circumferential direction. The carcass cord layer consists of only one layer and the reinforcing cord thereof makes an angle of 66.degree. to 82.degree. with respect to the circumferential direction of the tire.

Abstract: A pneumatic radial tire is disclosed which comprises a tread, a carcass cord layer and at least two belt reinforcing layers disposed between the tread and the carcass cord layer, the reinforcing cord of one of the belt reinforcing layers having an angle of 15 to 30 degrees with respect to the tire circumferential direction and the reinforcing cord of the other of the belt reinforcing layers having an angle of 150 to 165 degrees with respect to the tire circumferential direction. The carcass cord layer consists of upper and lower two layers, and the angle .alpha..sub.2 of the reinforcing cord of the upper carcass cord layer with respect to the tire circumferential direction and the angle .alpha..sub.1 of the reinforcing cord of the lower carcass cord layer with respect to the tire circumferential direction satisfy the following relations:1/2(.alpha..sub.1 +.alpha..sub.2)=96.degree. to 108.degree.(.alpha..sub.2 -.alpha..sub.1)=10.degree. to 40.degree..

Abstract: A pneumatic tire having a tread reinforcement layer constituted by a steel cord strip layer adjacent the carcass and an aromatic polyamide cord strip layer superposed to the steel cord strip layer in a parallel side-by-side relationship. The aromatic polyamide cord strip layer is folded at its both edges toward the center, in such a manner that the folded portions contact the main portion in a parallel side-by-side relationship. The main portion has a width ranging between 100 and 110% of the width of the tread surface, while the width of each folded portion ranges between 27.5 and 35% of the width of main portion. Furthermore, the free edge of each folded portion is located at a distance from the center of the outermost circumferential groove in the tread surface, which distance being between 25 and 75% of the distance between the outermost groove and the adjacent groove.