The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of the tire tread showing the design;
FIG. 2 is a front elevational view thereof, a rear elevational view is identical to the front elevational view, a top plan view is identical to the front elevational view, and a bottom plan view is identical to the front elevational view;
FIG. 3 is a left side view thereof, and a right side view thereof is identical to the left side view; and,
FIG. 4 is an enlarged, partial view of the tread in FIG. 1.
In the drawings, the broken lines showing portions of the sidewall and inner bead depict portions of the tire that form no part of the claimed design.