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 tire, the opposite side perspective being identical thereto;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a side elevation view of the right side thereof; and,
FIG. 4 is a side elevation view of the left side thereof.
In the drawings, the broken line disclosure of the tire sidewall and inner bead depicts environmental structure and forms no part of the claimed design.