Medium/heavy duty motor-vehicle tires provided with a tread of the universal type

A tire for medium/heavy duty motor vehicles for rotation in either a first driven rotation direction or in a second traction rotation direction, comprising:

• a tread having side edges;
• at least one pair of circumferential shoulder ribs positioned between respective side edges of said tread and respective circumferential shoulder grooves axially spaced apart from the side edges;
• at least one pair of intermediate circumferential ribs respectively positioned between said shoulder grooves and corresponding intermediate circumferential grooves axially spaced apart from said shoulder grooves;
• two circumferentially extending center ribs positioned between said intermediate grooves, said center ribs being disposed symmetrically to an equatorial plane of the tread and mutually separated by at least one auxiliary circumferential groove, each of said intermediate and center ribs being divided into a plurality of respective intermediate and center blocks, circumferentially respectively defined by intermediate and central transverse cuts in which the central transverse cuts define, in the axial width of the tread, at least one directional circumferential area positioned between the intermediate grooves, in which each center block has a cusp-shaped end portion facing in said first rotation direction, and a hollow-shaped end portion, at a circumferentially opposite position, the shape of which matches the cusp-shaped end portion of an adjacent center block, wherein said center blocks are linked up one after the other by effect of elastic deformations induced therein by the reactions transmitted from the ground when the tread rotates in said first direction, said intermediate cuts defining, at laterally opposite positions relative to said directional circumferential area, at least two tractive circumferential areas in which each of the intermediate blocks has a substantially rhomboidal configuration imparted by said cuts, obliquely directed to the circumferential direction of the tire, wherein when the tire rotates in said second traction rotation direction at least the intermediate blocks mutually diverge by effect of the elastic deformations induced by the reactions transmitted from the ground.