Steel cord for tire belt ply reinforcement

A steel cord for tire belt ply reinforcement of a vehicle, the steel cord comprising:

• a cord formed by periodically twisting n wires,
• wherein the n wires are compressed by rolling, and at least one of the n wires is compressed into a non-circular shape,
• when n is an odd number, a cross-section of one wire from among the n wires is circular due to the rolling, and cross-sections of n−1 wires from among the n wires are non-circular, and
• when n is an even number, cross-sections of two wires from among the n wires are circular due to the rolling, and cross-sections of n−2 wires from among the n wires are non-circular due to the rolling,
• wherein, when a wire of which a cross-section is circular due to the rolling is referred to as a first wire, a wire of which a cross-section is non-circular due to the rolling is referred to as a second wire,
• a ratio of a minor axis of the second wire to a diameter of the first wire is about 0.70 to about 0.98,
• wherein, when a diameter of the wires before the rolling is referred to as d (mm),
• a first strength (normal tensile, NT) is defined as 3,200-2,000×d (mm)+200 (MPa),
• a second strength (high tensile, HT) is defined as 3,500-2,000×d (mm)+200 (MPa),
• a third strength (super tensile, ST) is defined as 3,850-2,000×d (mm)+200 (MPa),
• a fourth strength (ultra tensile, UT) is defined as 4,200-2,000×d (mm)+200 (MPa),
• a fifth strength (mega tensile, MT) is defined as 4,600-2,000×d (mm)+200 (MPa), and
• a tensile strength of the second wires before the rolling is one of the second strength, the third strength, the fourth strength, and the fifth strength, and
• wherein, the second wires having a tensile strength of an n-th strength before the rolling are rolled to have a tensile strength of an n−1-th strength.