The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing my new design, it being understood that the pattern is repeated uniformly throughout the circumference of the tread;
FIG. 2 is a front elevational view thereof; a top plan view thereof is identical to the front elevational view; a rear elevational view thereof is identical to the front elevational view; and a bottom plan view thereof is identical to the front elevational view;
FIG. 3 is a right side view thereof; a left side view thereof is a mirror image of the right side view; and,
FIG. 4 is an enlarged fragmentary view from upper 4-4 to lower 4-4 in FIG. 2.
The broken lines illustrate environmental subject matter only and form no part of the claimed design. The stippling in the drawings depicts recessed portions of the claimed design.