The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing my design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a fragmentary enlarged front view;
FIG. 7 is a section view taken along line 7-7 in FIG. 6;
FIG. 8 is a section view taken along line 8-8 in FIG. 6; and,
FIG. 9 is a section view taken along line 9-9 in FIG. 6.
Broken lines show environmental portions of a tire that are not being claimed, and form no part of the claimed design. The light stippled surface shading represents the surface of the tire tread, and the dark stippled surface shading represents the recessed portion of the tread grooves, having the depth as shown in FIGS. 7, 8, and 9.