In order to obtain satisfactory performance during travel in particular on a wet road, it is known to provide a tread of a tire with a tread pattern formed by tread pattern elements which are separated from each other by cutouts (grooves of average width greater than or equal to 2.5 mm and incisions of average width less than 2.5 mm), these cutouts being obtained for example by molding. The tread pattern elements thus formed comprise a contact face intended to come into contact with the roadway during travel and lateral faces also defining the cutouts; the intersection of each lateral face with the contact face forms a ridge which facilitates the contact of the tire with the roadway, and in particular when the latter is wet. More generally, a ridge is defined as the geometric limit of contact of a tread pattern element with the ground during travel.
Among tread pattern elements, a distinction is made between elements which do not run right around the tire (blocks) and elements which do run right around it (ribs). Furthermore, the tread pattern elements may comprise one or more incisions to form additional ridges, when each incision may or may not open on to at least one lateral face of the tread pattern element. By definition, an incision is the space defined by two main opposing faces distant from each other by a width of less than 2.5 mm.
In improving the grip of the tire on a damp road, it is known that the very nature of the rubber mix (alternatively referred to as “rubber composition”) forming the tread has a significant effect. Thus, a tread of a tire made of rubber mix having a better grip on wet ground makes it possible to obtain improved performance during travel in wet ground conditions. However, in parallel to this improvement in grip performance on wet ground, a loss of wear performance on a dry road occurs, which results in a reduced wear life and necessitates more frequent changing of the tires on a vehicle.
Consequently, there is a need for a tire the tread of which retains good wear life performance while substantially improving the grip performance on wet ground.
USPTO Backgrounds
USPTO Backgrounds