The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of the tire tread of our design;
FIG. 2 is a front elevation view of the tire tread of our design;
FIG. 3 is a side elevation view of the tire tread of our design; and,
FIG. 4 is a side elevation view of the tire tread of our design, taken from the opposite side of that shown in FIG. 3.
In the drawings, the broken lines depict environmental subject matter that forms no part of the claimed design. The dash-dot lines represent the peripheral boundary of the claimed design. The tread pattern is understood to repeat uniformly throughout the circumference of the tire.