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;
FIG. 3 is a top view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a fragmentary enlarged front view;
FIG. 7 is a sectional view taken along line 7-7 in FIG. 6; and,
FIG. 8 is a sectional view taken along line 8-8 in FIG. 6.
The dot dash dot lines represent boundaries between claimed and unclaimed subject matter, and the regularly spaced dash lines show portions of the tire not being claimed.