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, it being understood that the pattern is repeated uniformly throughout the circumference of the tread;
FIG. 2 is a front elevational view thereof; a top plan view thereof is identical to the front elevational view; a rear elevational view thereof is a mirror image of the front elevational view; and a bottom plan view thereof is identical the front elevational view;
FIG. 3 is a right side view thereof; and a left side view thereof is a mirror image of the right side view; and,
FIG. 4 is an enlarged cross-sectional view taken along line 4-4 to line 4-4 of FIG. 2.
The broken lines illustrate environmental subject matter only and form no part of the claimed design. The dash-dot-dash broken lines define the boundary of the tire tread and form no part of the claimed design. Surface shading lines and stippling form no part of the claimed design.