The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a left side elevation view thereof; and,
FIG. 5 is an enlarged fragmentary perspective view thereof.
The broken lines depict environmental subject matter that forms no part of the claimed design. The dot-dot-dash lines represent the peripheral boundary between the tire tread and the unclaimed sidewall. The tread pattern is understood to repeat uniformly throughout the circumference of the tire.