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

A medium/heavy duty vehicle comprising:

• driven and tractive axles;
• tires mounted respectively to the axles,
• the driven axle being an axle for respectively submitting each tire mounted to the driven axle to a driven rotation direction by effect of contact of the respective tire with the ground, the tractive axle being an axle for respectively submitting each tire mounted to the tractive axle to a traction rotation direction by effect of a tractive torque, each tire mounted to the driven axle and each tire mounted to the tractive axle being of identical construction, each tire 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;
• at least one circumferentially extending center rib positioned between said intermediate grooves, 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,
• the central transverse cuts defining, 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 a circumferential direction, and a hollow shaped end portion, at a circumferentially opposite position, the shape of the hollow-shaped end portion 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 driven rotation direction,
• said intermediate cuts defining, at lateral 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 intermediate cuts, obliquely directed to the circumferential direction of the tire, wherein when the tire rotates in said traction rotation direction at least the intermediate blocks mutually diverge by effect of the elastic deformations induced by the reactions transmitted from the ground, wherein said cusp-shaped portions of said tires, mounted on the driven axle face the rotation direction and said cusp-shaped portions of said tires, mounted on the tractive axle, face opposite the rotation direction.

A tire for use on a driven or tractive axle of a medium/heavy duty vehicle 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 orooves axially spaced apart from said shoulder grooves;
• at least one circumferentially extending center rib positioned between said intermediate grooves, 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,
• the central transverse cuts defining, 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, and a hollow-shaped end portion, at a circumferentially opposite position, the shape of the hollow-shaped end portion 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 a driven rotation direction,
• said intermediate cuts defining, at lateral 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, in which each of the intermediate cuts is positioned as an imaginary rectilinear extension of an adjacent stretch of one of the center cuts,
• wherein when the tire rotates in a tractive rotation direction at least the intermediate blocks mutually diverge by effect of the elastic deformations induced by the reactions transmitted from the ground,
• said tire being suitable for mounting on a driven axle with said cusp-shaped portion facing the traction rotation direction or on a tractive axle wherein the tire is circumferentially reversed with respect to the mounting on the driven axle,
• wherein the shoulder ribs have surface sipes, respectively in alignment with an imaginary extension of one of every two intermediate cuts defining a respective intermediate block, at the rate of one sipe for every two intermediate cuts, said surface sipes having a depth of not greater than 5 mm.

A tire for use on a driven or tractive axle of a medium/heavy duty vehicle 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;
• at least one circumferentially extending center rib positioned between said intermediate grooves, 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,
• the central transverse cuts defining, 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, and a hollow-shaped end portion, at a circumferentially opposite position, the shape of the hollow-shaped end portion 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 a driven rotation direction,
• said intermediate cuts defining, at lateral 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, in which each of the intermediate cuts is positioned as an imaginary rectilinear extension of an adjacent stretch of one of the center cuts,
• wherein when the tire rotates in a tractive rotation direction at least the intermediate blocks mutually diverge by effect of the elastic deformations induced by the reactions transmitted from the ground,
• said tire being suitable for mounting on a driven axle with said cusp-shaped portion facing the traction rotation direction or on a tractive axle wherein the tire is circumferentially reversed with respect to the mounting on the driven axle
• wherein said central cuts have first and second consecutive stretches to form said cusp-shaped end portion and said hollow-shaped end portion of each center block, wherein said first stretch has a different length than said second stretch and said first stretch forms a different angle with a phantom line which passes through a point of intersection of the two consecutive stretches in a direction transverse to a circumference of the tire.