Pirelli Pneumatici S.p.a.

Pirelli Tyre S.p.a.

Mario Isola

Gianfranco Colombo

Antonio Serra

Angela Amaddeo

Giovanni Tamanza

Sidewall of a tire

A tire for a vehicle wheel includes a carcass structure, a belt structure associated coaxially with the carcass structure, and a tread band extending coaxially around the belt structure. The tread band includes a relief pattern including at least one row of blocks separated by transverse grooves intersecting two circumferential grooves. Each block of the at least one row is essentially delimited by two longitudinal sides in a circumferential direction of the tire and two transverse sides with respect to a predetermined rolling direction of the tire. Each block of the at least one row is formed by two axially-adjacent block portions. The transverse sides of each block portion include at least two successive curvilinear portions shaped differently from each other. The transverse grooves include two branches, each branch including a widened cross-section of substantially-curvilinear shape disposed in an area substantially equidistant from ends of a respective branch.

Tyre for a vehicle wheel including specific tread patterns

Winter tire for vehicle wheels, provided with a tread comprising three circumferential grooves and a plurality of transverse grooves which jointly delimit four circumferential rows of blocks, namely two axially outer shoulder rows and two center rows at the sides of the equatorial plane. The transverse grooves converge on the equatorial plane in the direction of rolling specified for the tire. In the tread, each transverse groove of the center rows is made to comprise a widening of the cross section with an essentially circular profile, formed at a distance from the ends, for trapping snow. To obtain quieter running on dry roads, the front transverse edge profiles of the adjacent blocks of the center rows are made to comprise at least two successive curvilinear portions. These curvilinear portions are shaped in different ways and with opposite curvatures to each other, to form means of attenuating the noise arising from the impact of the tread pattern on dry roads when the tire is rolling.

A low rolling resistance tire ( ) for vehicles is described which comprises at least one belt layer ( ) coaxially extending around at least one carcass ply ( ), a composite tread ( ) coaxially extending around the belt layer ( ) and comprising a radially outer layer ( ) and a radially inner layer ( ), wherein the ratio between the modulus of elasticity E' at 70&deg; C. of the radially inner layer ( ) and the modulus of elasticity E' at 70&deg; C. of the radially outer layer ( ) is comprised between 1.1 and 3, and the ratio between the value of tang&dgr; at 70&deg; C of the radially inner layer ( ) and the value of tang&dgr; at 70&deg; C. of the radially outer layer ( ) is lower than 0.8. Advantageously, the tire ( ) achieves a better compromise between the characteristics of rolling resistance, handling and comfort with respect to what is obtainable from known tires for the same type of use.

Growing community of inventors

Milan, Italy

Mario Isola