Abstract: A pneumatic tire has two belt layers, each having a plurality of strip pieces formed by pulling together and rubberizing a plurality of steel cords. Strip piece width, strip piece thickness, belt layer cord angle with respect to a tire circumferential direction, numbers of the strip pieces of inner and outer belt layers, and circumferential lengths of the inner and outer belt layers are respectively denoted by A, G, ?, N1, N2, L1 and L2. N2 is equal to N1, and N1 is an integer satisfying L1=N1×A/sin ?. The inner belt layer is formed by joining the N1 strip pieces so each side of each strip piece is butted with one side of another strip piece. The outer belt layer is formed by aligning the N2 strip pieces on the inner belt layer in the tire circumferential direction with spaces of width 2?G/N2 disposed between adjacent strip pieces.

Abstract: Disclosed is a pneumatic tire in which formation of a belt layer is realized by using an integer number of strip pieces and without causing any overlap between the strip pieces, and a method of manufacturing the same. The method is a method of manufacturing a pneumatic tire provided with a belt layer composed of a plurality of strip pieces each of which is formed by pulling together and rubberizing a plurality of steel cords. In the method, when a width of the respective strip pieces, an applicable number of the strip pieces, a cord angle of the belt layer with respect to a circumferential direction of the tire, and a circumferential length of the belt layer are respectively denoted by A, N, ?, and L, an integer satisfying (N+1)×A/sin ?>L>N×A/sin ? is selected as the applicable number N, and the belt layer is formed by aligning the N strip pieces on a molding drum in the circumferential direction of the tire with equal spaces disposed between adjacent ones thereof.

Abstract: Disclosed is a method of designing rubber composite executed as follows. A shape of the rubber composite, a shape of the each part (i) constituting the rubber composite and physical properties of a rubber material used for each part (i) are tentatively selected respectively. Thereafter, the rubber composite is divided into many finite elements, and strain in each element is calculated by the finite element method to obtain maximum principal strain (?i)max of the elements in each part (i). Then, the tentative selections of the shape of the rubber composite, the shape of each part (i) and the physical properties of the rubber material, and the calculations by the finite element method are repeated until an allowance ratio Sia calculated as a ratio of strain (?i)b at break to the maximum strain (?i)max becomes equal to a specified reference allowance ratio S0 or higher in all of the parts (i).

Abstract: Disclosed is a method of designing rubber composite executed as follows. A shape of the rubber composite, a shape of the each part (i) constituting the rubber composite and physical properties of a rubber material used for each part (i) are tentatively selected respectively. Thereafter, the rubber composite is divided into many finite elements, and strain in each element is calculated by the finite element method to obtain maximum principal strain (&egr;i)max of the elements in each part (i). Then, the tentative selections of the shape of the rubber composite, the shape of each part (i) and the physical properties of the rubber material, and the calculations by the finite element method are repeated until an allowance ratio Sia calculated as a ratio of strain (&egr;i)b at break to the maximum strain (&egr;i)max becomes equal to a specified reference allowance ratio S0 or higher in all of the parts (i).

Abstract: A pneumatic radial tire has at least two belt layers disposed at a tread portion thereof, wherein the two belt layers are constituted by inclining a strip formed by aligning a plurality of reinforcing cords to a tire circumferential direction and extending it zigzag in the tire circumferential direction so that the strip is turned back from the lower belt layer to the upper belt layer at both end portions of the two belt layers, and zone portions in which the reinforcing cords incline to the right in the tire circumferential direction and the zone portions in which the reinforcing cords incline to the left in the tire circumferential direction are alternately arranged.

Abstract: A pneumatic tire for automobiles which has a carcass reinforced with polymeric monofilaments of the same or different diameter which are interconnected by radially inwardly curved peripheral extensions thereof to form a cord having a substantially flat transverse cross-sectional configuration as a whole.

Abstract: A pneumatic radial tire including a belt covering reinforcing layer comprising fiber cords each of which comprises a plurality of filaments of a core-sheath composite fiber which comprises a core component of a polyester polymer and a sheath component of a polyamide polymer.

Abstract: A pneumatic tire wherein a plurality of main grooves are provided in a tread of the tire in the circumferential direction thereof with a plurality of sub-grooves connecting these main grooves with each other being provided in the width-wise direction of the tire, wherein each of these sub-grooves is bent in a convex shape facing in the same direction relative to the circumferential direction of the tire, and wherein bending points of the sub-grooves are distributed within those areas in the tread of the tire which extend, respectively, from a tire equator line toward opposite sides of the tire in the width-wise direction thereof over a distance equal to 5 to 25% of the tread ground-contacting width in such a manner that the number of the bending points become substantially equal on either side of the equator line.

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: 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 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.