Car tyre
AssigneePirelli Tyre S.p.A.
InventorsGianfranco Colombo, Roberto Bolzoni, Stefano Bizzi, Daniele Lorenzetti
Life of this patent
Estimating the term…
Abstract
A tyre having a tread is described. The tyre has a central portion located across an equatorial plane, a first shoulder portion located towards an outer side of the tyre and a second shoulder portion located towards an inner side of the tyre. The central portion is separated from the first shoulder portion by two first circumferential grooves. The first shoulder portion and the second shoulder portion have a plurality of first transverse grooves having a first end located substantially at the respective edge of the tread, having a width greater than or equal to about 4 mm and an axial extension equal to at least 50% of the width of the shoulder portion in which they are located.
Claims18
A car tyre having a tread comprising a central portion located across an equatorial plane, a first shoulder portion located towards an outer side of the tyre and a second shoulder portion located towards an inner side of the tyre, the central portion being separated from said shoulder portions by two first circumferential grooves having a respective minimum width of about 5 mm, wherein:
- said first shoulder portion and said second shoulder portion comprise a plurality of first transverse grooves having a first end located substantially at a respective edge of the tread, having a width greater than or equal to about 4 mm and an axial extension equal to at least 50% of the width of the shoulder portion in which they are located;
- said two first circumferential grooves are a first circumferential groove facing towards the outer side of the tyre and a first circumferential groove facing towards the inner side of the tyre;
- the number of said first transverse grooves of the first shoulder portion is lower than the number of said first transverse grooves of the second shoulder portion;
- said central portion has two circumferential ribs, a first and a second circumferential rib respectively, comprising a plurality of second transverse grooves;
- said central portion comprises one second circumferential groove so as to define said first and second circumferential ribs;
- said first circumferential rib being axially delimited by the first circumferential groove facing towards the outer side of the tyre and the second circumferential groove, said second circumferential rib being axially delimited by the first circumferential groove facing towards the inner side of the tyre and the second circumferential groove;
- said second transverse grooves have a maximum width smaller than or equal to about 3 mm, define in at least one of said circumferential rib a void-to-rubber ratio smaller than 0.06, and extend at most over 80% of a width of the circumferential rib in which they are located;
- each circumferential rib of the central portion has its own void-to-rubber ratio;
- said void-to-rubber ratio is greater in the circumferential rib closest to the second shoulder portion;
- and
- said second transverse grooves of the first circumferential rib extend from the second circumferential groove towards the equatorial plane.
Dependencies are inferred from the claim text.