The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread.
FIG. 2 is a front view of the tire tread of FIG. 1. The top and bottom plan views and the rear view are identical to the front view.
FIG. 3 is a left side view of the tire tread of FIG. 1. The right side view is identical to the left side view; and,
FIG. 4 is a detailed view of the section of FIG. 2 defined by the lines 4-4 shown in FIG. 2.
The broken lines illustrate environmental subject matter only and form no part of the claimed design. The surface shading lines and stippling in the drawings depict the character or contour of the surfaces represented and form no part of the claimed design.