The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tread showing our new design;
FIG. 2 is a front view of the tread;
FIG. 3 is a right view of the tread;
FIG. 4 is a left view of the tread;
FIG. 5 is an enlarged view of the tread with section lines corresponding to the views in FIGS. 6, 7, and 8;
FIG. 6 is a first transversal section view of the tread;
FIG. 7 is a second transversal section view of the tread; and,
FIG. 8 is a third transversal section view of the tread.
In the drawings, the broken lines defining the sidewall, inner bead and the peripheral boundary between the claimed tire tread and the unclaimed sidewall depict environmental subject matter that forms no part of the claimed design.