The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing my design;
FIG. 2 is a front view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a is a fragmentary enlarged front view surrounded by lines 5-5 and 5-5 in FIG. 2, showing the details of the tire tread; and,
FIG. 6 is a section view taken along line 6-6 in FIG. 5.
The regular broken lines are used to show unclaimed environment, and thus form no part of the claimed design. The alternating short and long broken lines represent a border between claimed and unclaimed subject matter. The dark stippled surface shading represents recessed portions of the tread grooves having a depth.