Tire tread comprising cutouts of different depths

A tread of a tire adapted to be fitted to an off-road vehicle, this tread having;

• a tread surface which is adapted to come into contact with the ground when the tire is running,
• a total width and a total thickness of wearable material at least equal to 60 mm,
• this tread being delimited axially by shoulder regions, each shoulder region having a width comprised between 15% and 35% of the total width of the tread and comprising a plurality of transverse or oblique grooves of depth (P),
• said shoulder-region grooves being arranged in the circumferential direction with a mean spacing,
• the tread further comprising a central region centered on the equatorial mid-plane and having a narrow groove that occupies the entire width of said central region,
• said narrow groove comprising an alternation of first narrow-groove parts and of second narrow-groove parts, said first and second narrow-groove parts being connected to each other by joining regions, a circumferential distance between two circumferentially adjacent joining regions within which a said first narrow groove part and a said second narrow groove part are received is equal to the mean spacing of the shoulder-region grooves,
• said tread comprising, between each said shoulder region and the central region, an intermediate region in which there are formed a plurality of oblique or transverse narrow grooves the mean orientation of which makes an angle at most equal to 60 degrees with the axial direction, each of said narrow grooves beginning in a joining region of the narrow groove of the central part and connecting into a transverse or oblique groove formed in one of the shoulders,
• wherein the narrow groove of the central part is comprised of first narrow-groove parts of depth (P1) and of second narrow-groove parts of depth (P2), the depth (P1) being greater than the depth (P2), said depths (P1, P2) being less than the depth (P) of the grooves in the shoulder regions, and
• wherein the narrow grooves of one same intermediate region comprise, in the circumferential direction, an alternation of said narrow grooves of a first depth (P11) and of narrow grooves of a second depth (P22), said depths (P11, P22) being less than the depth P of the grooves in the shoulder regions.