A motorcycle tyre has a tread band including a central portion and two shoulder portions arranged at axially opposite sides of the central portion. The central portion includes a first plurality of grooves extended according to a substantially longitudinal direction and alternatively arranged at opposite sides of the equatorial plane of the tyre. Each groove of the first plurality of grooves has a substantially curvilinear course such as to form a concavity. The central portion further includes a sub-portion substantially free of grooves placed astride the equatorial plane of the tyre. Each of the shoulder portions includes a second plurality of grooves arranged obliquely relative to the equatorial plane of the tyre.

An object of the invention is to provide a tire having little change in riding comfort performance and wet performance before and after wear of the tread part and in which riding comfort performance and wet performance as when the tire is newly used are maintained. The fire comprises a tread being composed of a rubber layer in which there is little change in hardness after thermal deterioration and having a groove shape such that a sea ratio after wear with respect to a sea ratio as when the tire is newly used is within a predetermined range.

An object of the invention is to provide a tire having good steering stability performance after wear and in which a decrease in wet performance after wear is suppressed. The tire comprises a tread being composed of a rubber layer in which change in hardness after thermal deterioration is within a predetermined range and having a groove shape such that a sea ratio after wear with respect to a sea ratio as when the tire is newly used.

The tread has a contact face that is provided with at least one circumferential groove and a transverse grooves opening to the contact face and delimiting contact elements. The tread has a center region and shoulder regions and is provided with at least one compressive contact element among the contact elements. A volumetric void ratio of the compressive contact element in a unit region surrounded by a center of the at least one circumferential groove and a center of the transverse grooves delimiting the compressive contact element is at least equal to 25%. An aspect ratio, which is defined as a ratio of a surface of the compressive contact element supposed to contact with ground divided by a sum of a surface area of the compressive contact element touching with air other than the surface of the compressive contact element supposed to contact with ground, is at most 70%.

A tire includes a first circumferential main groove 11 and a second circumferential main groove 12 in a tread surface 1. A resonator 21 is formed in an intermediate land portion 20 partitioned between the first circumferential main groove and the second circumferential main groove. The resonator has an auxiliary groove 211 whose both ends terminate within the intermediate land portion. The groove depths D1 of the first and second circumferential main grooves are 50% or less of the groove widths W2 of the first and second circumferential main grooves, respectively. The groove width W3 of the auxiliary groove of the resonator is 80% or less of the groove depth D1 of the first circumferential main groove.

Tire (1) for a heavy-duty vehicle of civil engineering type, and more particularly to the tread (2) thereof, and seeks to improve the grip thereof, while at the same time ensuring a satisfactory compromise with wearing and thermal endurance. The tread (2) comprises cuts (3, 4, 5) distributed, in a circumferential direction (XX′) of the tire, among circumferential grooves (3) and, in an axial direction (YY′) of the tire, transverse sipes (4) and transverse grooves (5), the cuts (3, 4, 5) delimiting elements in relief (6), each cut (3, 4, 5) being delimited by two faces facing one another and each face intersecting the tread surface (21) along an edge corner (311, 321; 411, 421; 511, 521). The tread (2) having a longitudinal edge corners ratio TA.sub.X equal to the ratio L.sub.X/S between the sum L.sub.X of the projections, on to the circumferential direction (XX′), of the effective edge corner lengths, contained in an elementary tread surface portion of surface area S, and the surface area S, and a transverse edge corners ratio TA.sub.Y equal to the ratio L.sub.Y/S between the sum L.sub.Y of the projections, onto the axial direction (YY′), of the effective edge corner lengths, contained in an elementary tread surface portion of surface area S, and the surface area S, the longitudinal edge corners ratio TA.sub.X is at least equal to 4 m.sup.−1 and the transverse edge corners ratio TA.sub.Y is at least equal to 6 m.sup.−1.

Heavy goods vehicle tire, having a crown portion covered radially on the outside by a tread, this tread having at least two cut-outs, the central portion of the tread having a width Lc of between 35% and 70%, the crown portion comprising a reinforcement having at least two working layers having reinforcing elements, these reinforcing elements consisting of UHT-grade threads, having a mechanical breaking strength R satisfying the following relation: R≥(4180−2130×D), where D is the diameter of the thread expressed in millimetres, this tread being formed of at least two layers of superimposed material, the material forming the first layer with a breaking elongation of more than 600% at a temperature of 60° C., this tread being such that, in the central portion, the cavity ratio per unit volume is not more than 10% and the surface cavity ratio as new is not more than 10%.

A tire includes, in a tread portion, a pair of shoulder main grooves, a crown region between the shoulder main grooves, and shoulder regions disposed outside of the shoulder main grooves in a tire axial direction. Land ratios of the crown region and the shoulder regions are respectively 40%-60%. In the crown region, a plurality of middle blocks are arranged on both sides of a tire equator, and each middle block has a longitudinal shape in which a length in the tire circumferential direction is larger than a length in the tire axial direction.

A motorcycle tyre (1) is described comprising an equatorial plane (X-X) and a tread band (8) comprising a radially inner portion (13) and a radially outer portion (11) respectively comprising a first and a second vulcanized elastomeric material obtained by vulcanizing respective elastomeric materials comprising 100 phr of at least one elastomeric diene polymer, from 30 to 130 phr of at least one reinforcing filler comprising an amount greater than 75% or, respectively, equal to or greater than 80% of a white filler. In the tyre (1) the ratio R1 between the dynamic elastic modulus (E′) and the tandelta measured at a frequency of 10 Hz and at 70° C. of the first vulcanized elastomeric material is comprised between 27 and 35, whereas the ratio R2 between the dynamic elastic modulus (E′) and the tandelta measured at a frequency of 10 Hz and at 70° C. of the second vulcanized elastomeric material is comprised between 15 and 30, the ratio R1/R2 being greater than or equal to 1.1.

A tyre comprises a tread portion comprising a shoulder main groove and a shoulder land region. The shoulder land region includes an outer region, a middle region, and an inner region. The shoulder land region is provided with a plurality of shoulder sipes having components in a tyre axial direction. A sipe ratio of the middle region is smaller than the sipe ratio of the outer region and the sipe ratio of the inner region.