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 tread pattern repeats uniformly around the outer circumference and shoulder of the tire, the opposite side perspective view being identical thereto;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a side elevational view of the right side thereof; and,
FIG. 4 is a side elevational view of the left side thereof.
In the drawings, the dark stippled surface shading represents the recessed groove portions of the tire tread having a depth as best illustrated along the top and bottom edges of FIG. 2. In the drawings, the broken line disclosure of the tire sidewall and inner bead depicts environmental structure and forms no part of the claimed design.