The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of the tire tread of the present application;
FIG. 2 is a side view (inside) thereof;
FIG. 3 is a side view (outside) thereof;
FIG. 4 is a front view thereof; and,
FIG. 5 is an enlarged partial front view thereof.
The remaining three-fourths of the side view is a repetition of the illustrated one-fourth portion. 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 forms no part of the claim.