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 repeats uniformly throughout the circumference of the tread;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a right side elevational view thereof; the other side being identical thereto; and,
FIG. 4 is an enlarged fragmentary front elevational view thereof.
In the drawings, the broken lines defining the sidewall, inner bead and the peripheral boundary between the tire tread and the sidewall are for illustrative purposes only and form no part of the claimed design.