A method is provided for manufacturing a multistrand cable having a 1×N structure and including a single layer of N strands wound in a helix. Each strand includes an internal layer of M internal threads and an external layer of P external threads. The method includes a step of individually assembling each of the N strands, during which, in chronological order, the M internal threads are wound, the P external threads are wound, and the M internal threads and the P external threads are elongated such that a structural elongation associated with the P external threads of each strand is greater than or equal to 0.05%. The method further includes a step of collectively assembling the N strands, during which the N strands are wound to form the cable.

A multi-strand cord (50) comprises an internal layer (CI) made up of K=1 internal strand (TI) having two layers (C1, C3), with the internal layer (C1) being made up of Q internal metallic threads (F1) and the external layer (C3) being made up of N external metallic threads (F3), and an external layer (CE) made up of L>1 external strands (TE) having two layers (C1′, C3′) wound around the internal layer (CI), with the internal layer (C1′) being made up of Q′ internal metallic threads (F1′) and the external layer (C3′) being made up of N′ external metallic threads (F3′). The cord (50) has an energy-to-break per unit area ES≥145 N.Math.mm.sup.−1 with ES=Σ.sub.i=1.sup.NcF.sub.mi×Σ.sub.i=1.sup.NcA.sub.ti/Nc×Cfrag/D where Σ.sub.i=1.sup.NcF.sub.mi is the sum of the forces at break, Σ.sub.i=1.sup.NcA.sub.ti is the sum of the total elongation, Cfrag is the coefficient of weakening, and D is the diameter.

A pneumatic radial tire includes belt layers disposed on an outer circumferential side of a carcass layer in a tread portion. The belt layers are formed of steel cords in a N+M structure in which the number of wire strands N of an inner layer is 2 to 4 and the number of wire strands M of an outer layer is 2 to 7. A twist direction of the inner layer is different from a twist direction of the outer layer. The steel cords are inclined with respect to a tire circumferential direction to intersect each other in layers of the belt layers. A belt cover layer disposed on an outer circumferential side of the belt layers is formed of organic fiber cords having elongation of 2.0% to 4.0% under 2.0 cN/dtex load. The organic fiber cords are wound spirally along the tire circumferential direction.

Rubber article-reinforcing steel cord in which corrosion resistance is improved without an increase in weight. In a rubber article-reinforcing steel cord (1), plural sheath strands (3) each formed by twisting together plural steel filaments are twisted together around at least one core strand (2) formed by twisting together plural steel filaments. Core strand (2) and sheath strands (3) are each formed by twisting together one or two core filaments (2c) and (3c) and plural sheath filaments (2s) and (3s), respectively, and a relationship represented by the following Formula (1) is satisfied when a wire diameter of core filament(s) (2c) of core strand (2), a wire diameter of sheath filaments (2s), a wire diameter of core filaments (3c) of sheath strands (3), and a wire diameter of sheath filaments (3s) are defined as dcc, dcs, dsc and dss, respectively: dcc>dcs≥dsc>dss (1).

A steel cord containing a core layer and an sheath layer, the core layer containing a plurality of core wires with a number of n and the sheath layer comprises a plurality of sheath wires with a number of m, and the steel cord has a flat cross-section with a major axis and a minor axis, the flat cross-section has a flat ratio being the ratio of the length of the major axis and the length of the minor axis, the flat ratio is more than 1.2, the steel cord has a breaking load being BL.sub.cord, the core wires and the sheath wires have a sum breaking load being Sum BL.sub.wires when the core wires and the sheath wires are un-twisted from the steel cord, BL.sub.cord and Sum BL.sub.wires satisfies the following formula: BL.sub.cord/Sum BL.sub.wires>96%. The steel cord has higher breaking load.

A steel cord containing a core layer and an sheath layer, the core layer containing a plurality of core wires with a number of n and the sheath layer comprises a plurality of sheath wires with a number of m, and the steel cord has a flat cross-section with a major axis and a minor axis, the flat cross-section has a flat ratio being the ratio of the length of the major axis and the length of the minor axis, the flat ratio is more than 1.2, the steel cord has a breaking load being BL.sub.cord, the core wires and the sheath wires have a sum breaking load being Sum BL.sub.wires when the core wires and the sheath wires are un-twisted from the steel cord, BL.sub.cord and Sum BL.sub.wires satisfies the following formula: BL.sub.cord/Sum BL.sub.wires >96%. The steel cord has higher breaking load.

A method is provided for manufacturing a multistrand cable having a 1N structure and including a single layer of N strands wound in a helix. Each strand includes an internal layer of M internal threads and an external layer of P external threads. The method includes a step of individually assembling each of the N strands, during which, in chronological order, the M internal threads are wound, the P external threads are wound, and the M internal threads and the P external threads are elongated such that a structural elongation associated with the P external threads of each strand is greater than or equal to 0.05%. The method further includes a step of collectively assembling the N strands, during which the N strands are wound to form the cable.

Rubber article-reinforcing steel cord in which corrosion resistance is improved without an increase in weight. In a rubber article-reinforcing steel cord (1), plural sheath strands (3) each formed by twisting together plural steel filaments are twisted together around at least one core strand (2) formed by twisting together plural steel filaments. Core strand (2) and sheath strands (3) are each formed by twisting together one or two core filaments (2c) and (3c) and plural sheath filaments (2s) and (3s), respectively, and a relationship represented by the following Formula (1) is satisfied when a wire diameter of core filament(s) (2c) of core strand (2), a wire diameter of sheath filaments (2s), a wire diameter of core filaments (3c) of sheath strands (3), and a wire diameter of sheath filaments (3s) are defined as dcc, dcs, dsc and dss, respectively: dcc>dcsdsc>dss (1).

A multi-strand cord (50) comprises an internal layer (CI) made up of K=1 internal strand (TI) having two layers (C1, C3), with the internal layer (C1) being made up of Q internal metallic threads (F1) and the external layer (C3) being made up of N external metallic threads (F3), and an external layer (CE) made up of L>1 external strands (TE) having two layers (C1, C3) wound around the internal layer (CI), with the internal layer (C1) being made up of Q internal metallic threads (F1) and the external layer (C3) being made up of N external metallic threads (F3). The cord (50) has an energy-to-break per unit area ES145 N.Math.mm.sup.1 with $ES={.Math.}_{i=1}^{Nc}{F}_{mi}{.Math.}_{i=1}^{Nc}{A}_{ti}/\mathrm{Nc}\mathrm{Cfrag}/D$
where ${.Math.}_{i=1}^{Nc}{F}_{mi}$
is the sum of the forces at break, ${.Math.}_{i=1}^{Nc}{A}_{ti}$
is the sum of the total elongation, Cfrag is the coefficient of weakening, and D is the diameter.

A method of manufacturing a metal cord with two concentric layers of wires is provided. The cord includes an internal layer of M wires, M having a value from 1 to 4, and an external layer of N wires. The cord is rubberized from within in situ. That is, during manufacture of the cord, the cord is rubberized from inside. According to the method, the internal layer is sheathed with rubber or a rubber compound by passing the internal layer through an extrusion head, and the N wires of the external layer are assembled around the sheathed internal layer to form a two-layer cord rubberized from the inside. The rubber is an unsaturated thermoplastic elastomer that is extruded in a molten state, and preferably is a thermoplastic styrene (TPS) type of thermoplastic elastomer, such as an SBS or an SIS block copolymer, for example.