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 elevation 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 broken lines defining the side wall and inner bead are for illustrative purposes only and form no part of the claimed design.