The ornamental design for a tire tread, as shown and described.
FIG. 1 is a side perspective view of a tire tread showing our new design, it being understood that the tread pattern is repeated throughout the circumference of the tire tread;
FIG. 2 is a front view thereof, the opposite side being identical thereto; and,
FIG. 3 is a side elevation view of the left side thereof, the right side elevation being identical thereto.
In the drawings, the broken lines showing portions of the sidewall and inner bead depict portion of the tire that form no part of the claimed design.