A cord (50) comprises: an internal strand (TI) comprising internal layer (C1) of Q=1 internal wire (F1), an intermediate layer (C2) of M intermediate wires (F2) wound around the internal layer (C1) with a pitch p2, an external layer (C3) of N external wires (F3) wound around the intermediate layer (C2) with a pitch p3; and L>1 external strands (TE) comprising an internal layer (C1′), an external layer (C3′). The external layer (CE) of the cord is wound around the internal layer (CI) of the cord in a direction of winding of the cord (50). Each external layer (C3, C3′) of each internal and external strand (TI, TE) is wound in the same direction of winding that is the opposite to the direction of winding of the cord (50). The external layer (CE) of the cord (50) is desaturated, and 0.36≤(p3−p2)/p3≤0.57.

A cord (50) comprises: an internal strand (TI) comprising internal layer (C1) of Q=1 internal wire (F1), an intermediate layer (C2) of M intermediate wires (F2) wound around the internal layer (C1) with a pitch p2, an external layer (C3) of N external wires (F3) wound around the intermediate layer (C2) with a pitch p3; and L>1 external strands (TE) comprising an internal layer (C1′), an external layer (C3′). The external layer (CE) of the cord is wound around the internal layer (CI) of the cord in a direction of winding of the cord (50). Each external layer (C3, C3′) of each internal and external strand (TI, TE) is wound in the same direction of winding that is the opposite to the direction of winding of the cord (50). The external layer (CE) of the cord (50) is desaturated, and 0.36≤(p3−p2)/p3≤0.57.

Provided is a rubber article-reinforcing steel cord having improved shear fatigue resistance while reducing the weight of the steel cord by using a wire of high tensile strength. The rubber article-reinforcing steel cord 10 is a steel cord 10 having a two-layer twisted structure comprising a core filament 11 composed of a plurality of filaments and a sheath filament 12 composed of a plurality of filaments twisted around the core filament 11, wherein the tensile strength of the core filament 11 is higher than the tensile strength of the sheath filament 12, and the core filament 11 and the sheath filament 12 are twisted together in the same direction and the same pitch.

Provided is a rubber article-reinforcing steel cord having improved shear fatigue resistance while reducing the weight of the steel cord by using a wire of high tensile strength. The rubber article-reinforcing steel cord 10 is a steel cord 10 having a two-layer twisted structure comprising a core filament 11 composed of a plurality of filaments and a sheath filament 12 composed of a plurality of filaments twisted around the core filament 11, wherein the tensile strength of the core filament 11 is higher than the tensile strength of the sheath filament 12, and the core filament 11 and the sheath filament 12 are twisted together in the same direction and the same pitch.

A cord (50) comprises: an internal strand (TI) comprising an internal layer (C1), and an external layer (C3); and L>1 external strands (TE) comprising an internal layer (C1′) of Q′=1 internal wire (F1′), an intermediate layer (C2′) of M′ intermediate wires (F2′) wound around the internal layer (C1′) with a pitch p2′, and an external layer (C3′) of N′ external wires (F3′) wound around the intermediate layer (C2′) with a pitch p3′. The external layer (CE) of the cord is wound around the internal layer (CI) of the cord in a direction of winding of the cord (50). Each external layer (C3, C3′) of each internal and external strand (TI, TE) is wound in the same direction of winding that is the opposite to the direction of winding of the cord (50). The external layer (CE) of the cord (50) is desaturated, and 0.36≤(p3′−p2′)/p3′≤0.57.

A cord (50) comprises: an internal strand (TI) comprising an internal layer (C1), and an external layer (C3); and L>1 external strands (TE) comprising an internal layer (C1′) of Q′=1 internal wire (F1′), an intermediate layer (C2′) of M′ intermediate wires (F2′) wound around the internal layer (C1′) with a pitch p2′, and an external layer (C3′) of N′ external wires (F3′) wound around the intermediate layer (C2′) with a pitch p3′. The external layer (CE) of the cord is wound around the internal layer (CI) of the cord in a direction of winding of the cord (50). Each external layer (C3, C3′) of each internal and external strand (TI, TE) is wound in the same direction of winding that is the opposite to the direction of winding of the cord (50). The external layer (CE) of the cord (50) is desaturated, and 0.36≤(p3′−p2′)/p3′≤0.57.

Provided are: a tire steel cord having not only excellent cutting resistance and corrosion resistance but also excellent processability in plant; and a pneumatic tire including the same. The tire steel cord has a layer-twisted structure including: a core 11 composed of two core filaments 1; and a sheath 12 composed of eight sheath filaments 2 that are twisted together around the core 11, in which tire steel cord the two core filaments 1 constituting the core 11 are twisted together, the twisting direction of the core filaments 1 and that of the sheath filaments 2 are different, and a diameter (Dc) of the core filaments 1 and a diameter (Ds) of the sheath filaments 2 satisfy a relationship represented by the following Equation (1):
0.90≤Ds/Dc≤1.10  (1).

Provided are: a tire steel cord having not only excellent cutting resistance and corrosion resistance but also excellent processability in plant; and a pneumatic tire including the same. The tire steel cord has a layer-twisted structure including: a core 11 composed of two core filaments 1; and a sheath 12 composed of eight sheath filaments 2 that are twisted together around the core 11, in which tire steel cord the two core filaments 1 constituting the core 11 are twisted together, the twisting direction of the core filaments 1 and that of the sheath filaments 2 are different, and a diameter (Dc) of the core filaments 1 and a diameter (Ds) of the sheath filaments 2 satisfy a relationship represented by the following Equation (1):
0.90≤Ds/Dc≤1.10  (1).

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.

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.