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, it being understood that the tread pattern repeats circumferentially throughout the outer circumference and shoulder of the wheel, the opposite side perspective being identical thereto;
FIG. 2 is a front elevation view thereof; and,
FIG. 3 is a side elevation view of the right side thereof, the left side elevation being identical thereto.
In the drawings, the recessed groove portions of the tire tread have a depth that is best illustrated along the top and bottom edges of FIG. 2. In the drawings, the broken line disclosure of the wheel along the sides depicts environmental structure and forms no part of the claimed design.