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 tire tread;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a right side elevational view thereof, the opposite side being a mirror image thereof; and,
FIG. 4 is a fragmentary front view, showing the tread pattern in greater detail.
The innermost left and right broken lines immediately adjacent the tire tread, best seen in FIG. 4, form the peripheral boundary of the claimed design; the broken lines in the drawing form no part of the claim.