The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire, showing my new design, it being understood that the pattern shown repeats uniformly throughout the circumference of the tread;
FIG. 2 is a front elevational view thereof, the back elevational view being a mirror image thereof; and,
FIG. 3 is a right side elevational view thereof, the opposing side being a mirror image thereof.
The broken line showing of the tire sidewall is included for the purpose of illustrating environment and forms no part of the claimed design.