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.

Provided is a steel cord for reinforcing rubber articles which, when applied to a belt of a tire, can attain lightweight without reducing the durability of the tire, and in particular, to a steel cord for reinforcing rubber articles in which the properties of a treat after rubberizing are excellent and a pneumatic radial tire using the same. Also provided is a steel cord for reinforcing rubber articles comprising a core formed by arranging two core filaments 1 in parallel without being twisted together, and N (2N4) sheath filaments 2 which are twisted together around the core. Letting the diameter of the core filament 1 be d1, and the diameter of the sheath filament 2 be d2, d1>d2.

A steel cord for reinforcing a breaker or belt ply in a rubber tire having a core group and a sheath group. The core group consists of two to four core steel filaments with a first diameter dc and the sheath group consists of one to six sheath steel filaments with a second diameter ds. The ratio dc/ds of the first diameter dc to the second diameter ds ranges from 1.10 to 1.70. The two core steel filaments are untwisted or have a twisting step greater than 300 mm. The sheath group is twisted around the core group with a cord twisting step in a cord twisting direction. The ratio of the difference in residual torsions of the core group and the sheath group to the difference in saturation level between the core group and the sheath group ranges from 0.10 to 0.65, preferably from 0.10 to 0.60.

A steel cord and a manufacturing process are disclosed. The steel cord includes a steel core wire located in the center and having a diameter of d; and M sheath-layer steel wires arranged around the steel core wire in the center, tangent to the steel core wire, and having a diameter of d1, at least two gaps L existing between the M sheath-layer steel wires, where M is 4; d, d1, and L satisfy the following relationship: 0.420<(d/d1)<0.800, d1 is between 0.20 mm and 0.44 mm, and L0.0008 mm. The steel cord of the present invention may allow rubber to be fully penetrated into the gaps, thereby reducing air content in the steel cord, avoiding point contact friction between the layers of steel wires due to insufficient rubber penetration, and further solving the problem of failure of the bearing capacity of the steel cord due to abrasion.

A steel cord with a construction of m+n having a first group of core filaments having a number of m and a second group of sheath filaments having a number of n, the second group and the first group are twisted around each other with the same twist pitch and same twist direction, wherein the core filaments are not twisted with each other, the core filaments are parallel or have a twist pitch being more than 300 mm, and the sheath filaments have a twist pitch being less than or equal to 30 mm, the core filaments have an average tensile strength Tc in MPa when being un-ravelled from said steel cord, the sheath filaments have an average tensile strength Ts in MPa when being un-ravelled from said steel cord, Tc and Ts satisfy: 5<(TcTs)<200. The steel cord has high breaking load and high production efficiency without cost increase.

The invention relates to a metallic reinforcing cord (10) for tyres for vehicle wheels, comprising a plurality of metallic wires (11) twisted to one another with a single twisting pitch (P), or a single metallic wire twisted with at least one second metallic wire with a single twisting pitch, or a plurality of first metallic wires twisted to one another with a first twisting pitch to define a first strand of metallic wires and at least one second metallic wire twisted with said first strand of metallic wires with a second twisting pitch equal to or different from the first twisting pitch. The metallic reinforcing cord (10) has a part load elongation greater than or equal to 1%.

The invention provides a steel cord with a construction of n1, n is the number of the steel filaments of the steel cord, the steel cord has an elongation at 2.5N-50N of less than 1.2% and a twist pitch of greater than 16 mm, each of the steel filaments has a form of helical wave with a wave length L expressed in mm and a wave height H expressed in mm when being unravelled from said steel cord, L is greater than 16 mm, each of the steel filaments has a space volume Vs satisfying that, Vs=LH.sup.2/4, and Vs>20 mm.sup.3. The invention steel cord is beneficial for the stress distribution.

The invention relates to a metallic reinforcing cord (10) for tyres for vehicle wheels, comprising from two to ten metallic wires (11) twisted together with a twisting pitch (P) and each having a predetermined diameter. In at least some cross sections of the metallic reinforcing cord (10), at least two of said metallic wires (11) are arranged to a minimum mutual distance greater than, or equal to, 2.5 times the predetermined diameter.

A multi-strand cord (50) comprises an internal layer (CI) of the cord made up of K=1 three-layer (C1, C2, C3) internal strand (TI), with the internal layer (C1) being made up of Q internal metallic threads (F1), the intermediate layer (C2) being made up of M intermediate metallic threads (F2) and the external layer (C3) being made up of N external metallic threads (F3), and an external layer (CE) of the cord made up of L>1 three-layer (C1, C2, C3) external strands (TE) wound around the internal layer (CI) of the cord, with the internal layer (C1) being made up of Q internal metallic threads (F1), the intermediate layer (C2) being made up of M intermediate metallic threads (F2) and the external layer (C3) being made up of N external metallic threads (F3). The cord (50) has an endurance criterion SL40 000 MPa.Math.mm with $SL=\max \left(\frac{{}_{\mathrm{bending}\_\mathrm{CI}}}{\mathrm{Cp}};\frac{{}_{\mathrm{bending}\_\mathrm{CE}}}{C_r\mathrm{Cp}}\right);$
and a size criterion Ec0.46 with Ec=Sc/Se.