The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing my our new design, it being understood that the opposite side view is identical thereto;
FIG. 2 is a full front elevation view of the tire tread of FIG. 1; and,
FIG. 3 is a side view of the tire tread of FIG. 1.
In the drawings, the broken lines defining the unclaimed sidewall, and inner bead depict environmental subject matter that forms no part of the claimed design.