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 front view thereof; and,
FIG. 3 is a side view thereof.
The other side of the tire is identical to FIG. 3. The broken line showings of the sidewall, inner bead, shoulder tread, 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 claim.