Tire tread for large motor vehicles

A tire tread comprises an elastomeric substance extending circumferentially about the axis of rotation of the tire:

• a pair of shoulders which flank the lateral edges of a ground engageable surface;
• at least three circumferentially extending grooves dividing the tread into continuous ribs of elastomeric material, the edges of the grooves, which separate the different ribs from each other being constituted by zig-zag shaped repetitive design units, said repetitive design units on either side of the grooves extending in circumferentially opposite directions and each said repetitive design unit having four legs, a first and third short leg alternating with a second and forth long leg, said edges of the grooves forming boundaries for a repetitive series of two axially adjacent blocks;
• a first and second alternating series of deep sipes in all the ribs with the exception of the shoulder ribs, the series each having three portions, the first and third portions being respectively in the continuation of the axially closest first legs and third legs of the design units which delimit opposing rib sides, the second or intermediate portions forming with the equatorial plane of the tire angles ranging between 50.degree. to 90.degree. while those of the first and third portions range between 30.degree. to 70.degree., said first and second alternating series of sipes forming with the edges of the grooves the boundaries of the two axially adjacent blocks;
• a third and fourth series of shallow sipes in all the ribs with the exception of the shoulder ribs, having each three portions, the second or intermediate portions forming with the equatorial plane an angle below 20.degree., the first and third portions being respectively situated in the continuation of said first and third portion of the deep sipes to form the parting line between the two axially adjacent blocks.