The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a full tire including the tire tread of the present application;
FIG. 2 is a partial side view thereof (and the remaining approximately three-quarters of the side of the tire is similar, and the other side is identical);
FIG. 3 is a front view thereof; and,
FIG. 4 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 is included for the purpose of illustrating environment and forms no part of the claim.