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;
FIG. 2 is a partial side view thereof (and the other side view is the same); and,
FIG. 3 is an enlarged partial front view thereof.
The broken line showings of the sidewall, inner bead, and the peripheral boundary between the tire tread and the sidewall, are included for the purpose of illustrating environment and form no part of the claimed tire tread. The tread pattern is understood to repeat throughout the circumference of the tire.