A hybrid tire cord has more uniform physical properties, and improved strength and fatigue resistance. The hybrid tire cord can easily be manufactured. The hybrid tire cord includes a nylon primarily twisted yarn and an aramid primarily twisted yarn, wherein the nylon primarily twisted yarn and the aramid primarily twisted yarn are secondarily twisted together, and after untwisting of the secondary twisting of the hybrid tire cord having a predetermined length, a length of the aramid primarily twisted yarn is 1.005 to 1.025 times a length of the nylon primarily twisted yarn.

An object of the present invention is to provide: a rubber-fiber composite obtained by coating a core-sheath fiber with a rubber, in which adhesion between the rubber and the fiber is improved and which is thereby allowed to exhibit an improved durability as compared to conventional rubber-fiber composites when used as a reinforcing material; a rubber-resin composite; and a pneumatic tire using the same. The rubber-fiber composite is obtained by coating a reinforcing material with a rubber, which reinforcing material is composed of a core-sheath type composite fiber whose core portion is constituted by a high-melting-point resin having a melting point of 150 C. or higher and sheath portion is constituted by an olefin-based polymer having a melting point lower than that of the high-melting point resin.

Technique to increase the endurance of tires comprising two crossed working layers (41, 42), comprising mutually parallel reinforcing elements that form, with the circumferential direction (XX) of the tire, an angle which is at least equal to 20 and at most equal to 50. The reinforcing elements are made up of individual metal threads or monofilaments having a cross section which is at least equal to 0.20 mm and at most equal to 0.5 mm. The tire also comprises axially exterior sipes (24) having a mean width W at most equal to 1 mm, of a depth D at least equal to 5 mm and spaced apart, in the circumferential direction (XX), by a circumferential spacing P at least equal to 4 mm, and axially exterior grooves (25) having a mean width W at least equal to 1 mm, of a depth D at most equal to 5 mm.

A dipped and heat-set high modulus nylon 6.6 cords having a tensile stress value between 1.2 and 2.0 cN/dtex at 4% elongation. The high modulus nylon 6.6 cords are used as reinforcement in shaped rubber composites. The minimum heat shrinkage of the cords is 4% and the maximum heat shrinkage thereof is 7%.

Technique to increase the endurance of tires comprising two crossed working layers (41, 42), comprising mutually parallel reinforcing elements forming, with the circumferential direction (XX) of the tire, an angle which is at least equal to 20 and at most equal to 50. The reinforcing elements are made up of individual metal threads or monofilaments having a cross section which is at least equal to 0.20 mm and at most equal to 0.5 mm. The tire also comprises grooves comprising a radially inferior zone Z1 having a radial height h1 equal to D/3, and a radially superior zone Z2 having a radial height h2 equal to 2D/3. These grooves have a mean width W at least equal to 1 mm and a depth D at least equal to 5 mm, and a maximum width W1 of zone 1, at least equal to 2 mm and a width of zone 2 at most equal to 1 mm.

A pneumatic tire is provided with carcass layers and belt layers, which constitute tire components that extend in a tire circumferential direction, and at least one thread having a strength at break of 100 N or less that extends in the tire circumferential direction and is disposed at a step portion formed at width-directional end portions of the carcass layers and the belt layers.

The present disclosure relates to a method for manufacturing a hybrid tire cord that utilizes a difference in fineness using a general-purpose industrial filament such as nylon and polyester having high fineness of 200 denier or more relative to a fineness of an aramid filament.

The tire has a radial carcass reinforcement, the seat diameter of which is strictly greater than 19.5 inches. The metal reinforcing elements of the at least one layer of the carcass reinforcement are layered cords which include several steel threads that have a weight content of carbon C such that 0.01%C<0.4%. The at least one carcass reinforcement layer has a breaking force per unit width of between 35 daN/mm and 75 daN/mm, and the diameter of the cords is greater than 0.7 mm.

The tire has a radial carcass reinforcement which includes at least one layer of metal reinforcing elements and a crown reinforcement, which is capped radially with a tread. The metal reinforcing elements of at least one layer of the carcass reinforcement are cords with several steel threads that have a weight content of carbon C such that 0.01%C<0.4%. The cords exhibit, in the permeability test, a flow rate of less than or equal to 20 cm.sup.3/min. The thickness of the rubber compound between the inner surface of the tire cavity and the point of a metal reinforcing element of the carcass reinforcement that is closest to the inner surface of the cavity is less than 3.2 mm, and the steel threads have a maximum tensile strength R, expressed in MPa, such that R175+930.0-600.ln(d) and R1500 MPa.

The tire has a radial carcass reinforcement which includes at least one layer of metal reinforcing elements. The tire also has a crown reinforcement, itself capped radially with a tread. The tread is joined to two beads via two sidewalls. The metal reinforcing elements of at least one layer of the carcass reinforcement are cords include several steel threads having a weight content of carbon C such that 0.01%C<0.4%. The cords exhibit, in the permeability test, a flow rate which is strictly greater than 20 cm.sup.3/min, and the thickness of the rubber compound between the inner surface of the tire cavity and the point of a metal reinforcing element of the carcass reinforcement that is closest to the inner surface of the cavity is less than 3.2 mm.