The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing our new design, it being undestood that the tread pattern is repeated throughout the circumference of the tire, and that the broken line illustrates the location of a sidewall and bead, but forms no part of the claimed design; and,
FIG. 2 is an enlarged fragmentary plan view of the tire tread illustrated in FIG. 1.
In the drawings, the dark stippled surface shading represents the recessed portion of the tread grooves, having the depth shown along the right edge of FIG. 1.