Hybrid cords for tire reinforcement

1. A hybrid cord for reinforcing tires, the cord comprising:

a core of at least one p-aramid filament and

a sheath of steel strands helically wound around the p-aramid filament;

wherein the p-aramid filament has a modulus greater than about 6.5 N/dTex.

2. The hybrid cord of claim 1 , wherein the steel strands each consist of a single steel wire.

3. The hybrid cord of claim 1 , wherein the steel strands each consist of cables made by twisting together multiple steel wires.

4. The hybrid cord of claim 1 , wherein greater than 90% of the outside surface of the core is covered by the sheath.

5. The hybrid cord of claim 1 , wherein the helical angle is between about 8 and 21°.

6. The hybrid cord of claim 1 , wherein the sheath is made of fine steel wire having a diameter of between about 0.04 mm and 0.125 mm.

7. A support structure for a tire, comprising one or more hybrid cords according to claim 1 and a supporting matrix.

8. The support structure of claim 7 , which is a belt.

9. The support structure of claim 7 , which is a carcass.

10. The support structure of claim 7 , which is a bead reinforcement chafer.

11. A tire comprising one or more hybrid cords according to claim 1 .

12. A method for manufacturing a hybrid cord comprising the steps:

providing a core of at least one p-aramid filament having a modulus greater than about 6.5 N/dTex and

wrapping the core with a plurality of steel strands, so as to form a sheath of steel strands.

13. A method for manufacturing a support structure for a tire, comprising the step of embedding the hybrid cord of claim 1 in a support matrix.

14. A method for manufacturing a tire, comprising the step of incorporating a support structure according to claim 7 into a tire.