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;
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; and,
FIG. 5 is an enlarged, partial view of FIG. 1.
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.