The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of the tire tread showing our new design, it being understood that the pattern repeats uniformly throughout the circumference of the tread;
FIG. 2 is a partial front elevational view thereof;
FIG. 3 is a side view thereof, the opposite side being identical thereto; and,
FIG. 4 is an enlarged front perspective view thereof.
The broken lines shown are included for the purposes of illustrating the unclaimed portions of the article and form no part of the claimed design.