The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing my new design; it being understood that the pattern repeats uniformly throughout the circumference of the tread;
FIG. 2 is a partial side view thereof; the opposite side being identical thereto;
FIG. 3 is a front view thereof;
FIG. 4 is an enlarged partial front view thereof; and,
FIG. 5 is an enlarged partial perspective view thereof.
The tire tread is symmetrical. The broken line in the figure drawings represents unclaimed portion of the design only and forms no part of the claim.