A tire having a tread comprising two shoulder ribs and at least one main rib, wherein the two shoulder ribs and the at least one main rib form at least two shoulder grooves. The two shoulder grooves each have a plurality of inboard walls and a plurality of outboard walls, each disposed at a substantially constant angle from a base of the shoulder groove to a shoulder rib surface. Further, the plurality of inboard walls includes a first set of walls disposed at a first angle from the base of the shoulder groove to a main rib surface and a second set of walls disposed at a second angle from the base of the shoulder groove to the main rib surface.