The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire, showing my new design, it being understood that the pattern shown repeats uniformly throughout the circumference of the tread;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a right side elevational view thereof; the opposing side being a mirror image thereof; and,
FIG. 4 is a fragmentary frontal view thereof showing the tread pattern in greater detail.
In the drawings, the broken lines defining the tire depict environmental subject matter that forms no part of the claimed design.