The ornamental design for tire tread, as shown and described.
FIG. 1 is a side elevation view of the tire tread design, the other side being substantially identical thereto;
FIG. 2 is a front elevation view thereof, the rear elevation being substantially identical thereto;
FIG. 3 is a top, front perspective view thereof; and,
FIG. 4 is a front elevation view showing a portion of the tire tread design.
The broken line depiction of lettering and numbers that appear, and the inner bead and sidewall of the tire, including the peripheral boundary adjacent to the shoulder blocks of the tire, are unclaimed environmental subject matter.