A steel cord for rubber reinforcement comprises a first group of core filaments (105) having a number of m and a second group of sheath filaments (110) having a number of n, m is three or four, the core filaments (105) are forming a helix, the core filaments (105) are not twisted together and being substantially parallel or the core filaments (105) have a twist pitch being more than 300 mm; the second group and the first group are twisted with each other, and the sheath filaments (110) are forming a flattened helix in the same direction of the helix of the core filaments (105), and the sheath filaments (110) have a cord twist pitch, at any cross-section of the steel cord, at least one interstice between two adjacent core filaments (105) is present. The steel cord has improved abrasion resistance and can contribute to the reduction of the weight of the tire.

A tire includes a tread and a crown reinforcement arranged radially internal to the tread. The crown reinforcement includes a protective reinforcement and a working reinforcement. The protective reinforcement includes a protective ply that exhibits a force at break greater than or equal to 1300 daN.Math.cm.sup.1. The protective ply includes protective reinforcing elements, each of which exhibits a force at break greater than or equal to 3000 N. The working reinforcement is arranged radially internal to the protective reinforcement and includes a working ply. The working ply includes working reinforcing elements, each of which includes a working cord formed of at least a strand that includes an external layer of unsaturated threads.

A two-layer multi-strand cord (60) has a modulus EC such that 50 GPaEC160 GPa. The cord comprises: (a) an internal layer (CI) of the cord made up of J>1 internal strands (TI) wound in a helix having a modulus EI, each internal strand (TI) comprising: an internal layer (C1) made up of Q1 internal threads (F1), and an external layer (C2) made up of N>1 external threads (F2) wound around the internal layer (C1), and (b) an external layer (CE) of the cord made up of L>1 external strands (TE) wound around the internal layer (CI) of the cord, each external strand (TE) comprising: an internal layer (C1) made up of Q1 internal threads (F1), and an external layer (C2) made up of N>1 external threads (F2) wound around the internal layer (C1).

A two-layer multi-strand cord (60) comprises an internal layer (CI) of the cord made up of J>1 internal strands (TI) and an external layer (CE) of the cord made up of L>1 external strands (TE). The cord satisfies the relationship 95MC175, where MC=(JMI+LME)/(J+L); MI=200cos.sup.4()[Q(D1/2).sup.2cos.sup.4()+P(D2/2).sup.2cos.sup.4()+N(D3/2).sup.2cos.sup.4()]/[Q(D1/2).sup.2+P(D2/2).sup.2+N(D3/2).sup.2]; and ME=200cos.sup.4()[Q(D1/2).sup.2cos.sup.4()+N(D2/2).sup.2cos.sup.4()]/[Q(D1/2).sup.2+N(D2/2).sup.2], where D1, D1, D2, D2, and D3 are in mm, and are the helix angle of each internal and external strand (TI), and are the helix angle of each internal thread (F1, F1), is the helix angle of each intermediate thread (F2) and and are the helix angle of each external thread (F3, F2).

A two-layer multi-strand cord (60) comprises an internal layer (CI) of the cord made up of J>1 internal strands (TI) and an external layer (CE) of the cord made up of L>1 external strands (TE). The cord satisfies the relationship 95MC175, where MC=(JMI+LME)/(J+L); MI=200cos.sup.4()[Q(D1/2).sup.2cos.sup.4()+N(D2/2).sup.2cos.sup.4()]/[Q(D1/2).sup.2+N(D2/2).sup.2]; and ME=200cos.sup.4()[Q(D1/2).sup.2cos.sup.4()+P(D2/2).sup.2cos.sup.4(6)+N(D3/2).sup.2cos.sup.4()]/[Q(D1/2).sup.2+P(D2/2).sup.2+N(D3/2).sup.2], where D1, D1, D2, D2, and D3 are in mm, and are the helix angle of each internal and external strand (TI), and are the helix angle of each internal thread (F1, F1), is the helix angle of each intermediate thread (F2) and and are the helix angle of each external thread (F2, F3).

The invention provides a steel cord for rubber reinforcement. The steel cord comprises a core strand and at least three outer strands twisted around the core strand, the core strand comprises at least one first core filament and multiple first outer filaments twisted around the first core filament, each outer strand comprises a number of second filaments, at least one of multiple first outer filaments is preformed prior to being twisted into the core strand, and at least one of second steel filaments is straight prior to being twisted to form each outer strand. The steel cord has improved performance on core filament migration.

The invention provides a steel cord for rubber reinforcement. The steel cord comprises a core strand and at least three outer strands twisted around the core strand, the core strand comprises at least one first core filament and multiple first outer filaments twisted around the first core filament, each outer strand comprises a number of second filaments, at least one of multiple first outer filaments is preformed prior to being twisted into the core strand, and at least one of second steel filaments is straight prior to being twisted to form each outer strand. The steel cord has improved performance on core filament migration.

A cable as may be used in a tire, including a pneumatic tire. The cable is constructed in a manner that can provide a desired stiffness to a tire as well as a certain amount of structural elongation. The cable can be provided in a manner that does not necessarily result in an increase in the overall weight of the tire as would occur by e.g., increasing the diameter of a conventional cable construction.

Provided is a steel cord for rubber article reinforcement, which has both the tensile strength in the cord axial direction and the strength in the shear direction at higher levels. A steel cord (10) for rubber article reinforcement includes: a single core strand (11) having a layer-twisted structure; and plural sheath strands (12) each having a layer-twisted structure, and the sheath strands (12) are twisted around the core strand (11). In the sheath strands (12), a ratio between the diameter of a core filament (12a) and the diameter of a sheath filament (12b) is 0.75 to 0.85, and a ratio between the strength of the core filament (12a) and the strength of the sheath filament (12b) is 0.55 to 0.7.

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.