The ornamental design for a tire tread, as shown and described.
FIG. 1 is a side perspective view of a tire tread showing the 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 show a portion of the sidewall and the inner beads depict a portion of the tire that form no part of the claimed design.