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 side view thereof;
FIG. 3 is a side view, showing the opposite side from FIG. 2;
FIG. 4 is a front view thereof; and,
FIG. 5 is an enlarged fragmentary front view thereof.
The broken line showings of the sidewall, inner bead, and the peripheral boundary between the tire tread and the sidewall is included for the purpose of illustrating environment and forms no part of the claim.