Pirelli Coordinamento Pneumatici S.p.a.

Societa' Pneumatici Pirelli

Industrie Pirelli S.p.a.

Romano Guermandi

Maurizio Boiocchi

Renato Caretta

Gianfranco Colombo

Gian Carlo Cucco

Fikret Semin

A tire (,) for motor-vehicle wheels comprises a tread band (,) and a belt structure (,), the tread band being molded with a raised pattern having a circumferential groove (,). In the absence of load and inflating pressure, the tire is characterized in that the belt structure in a cross-section of the tire has an axial profile comprising three distinct portions, first (,) and second (,) side portions and one central portion (,) interposed between the side portions. The side portions are concave at a radially internal position, in which the concavity is defined for each portion by a respective center and a respective radius of curvature. The central portion is concave at a radially external position where the concavity center of the central portion lies in the center line plane of the circumferential groove, in which the depth of the radially external concavity is canceled under the effect of the normal inflating pressure of the tire.

Tire with specified belt profile in the absence of load and inflating pressure

Tire

Vehicle tire

Tire for a vehicle wheel

The invention concerns a tread pattern of the directional type for automobile tires that are intended for highpowered vehicles and for exacting conditions of usage caused by the great acceleration used and the very high speeds reached during such driving, even when cornering. The tread pattern comprises a plurality of small blocks having a substantially rhomboidal form disposed in at least six axially spaced and circumferentially extending rows, which are separated from each other by straight circumferentially extending grooves and by oblique transversal grooves. The grooves of the two axially centered rows are disposed astride the equatorial plane of the tire and are inclined in the contrary sense in each row, both with respect to the next row and with respect to the oblique grooves of the other remaining rows disposed in the same midplane as the tread band.

Directional tires for automobiles

A process is provided for the manufacture of radial tires for vehicle wheels, having an annular reinforcement structure inserted between the tread and the casing. The reinforcement structure has two layers of metal cord and in a radially outer position a third layer of cords arranged in a longitudinal direction. The third layer is made of a textile material which shrinks when heated. The process comprises the steps of first shaping the vulcanized casing to form a toroid, then applying to the shaped casing the two layers of metal cords together with a portion of the layer of textile cords at each side zone of the reinforcement structure. The width of the side zone is between 1/3 and 1/10 of the total width of the structure. The casing is shaped a second time to increase the external equatorial development thereof to a value greater than that reached during the first shaping step. The remaining central portion of the layer of textile cord is then applied on top of the layers of metal cords. A band of elastomeric material, forming the tread of the carcass is disposed on top of the layer of textile cords. The structure is then expanded and vulcanized in a pressurized mold.

Process for manufacturing tires

Growing community of inventors

Milan, Italy

Romano Guermandi