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, and a rear elevational view is an upside-down image of the front elevational view; FIG. 2 is also a bottom plan view, and a top plan view is an upside-down image of the bottom plan view;
FIG. 3 is a left side view thereof, and a right side view is a mirror image of the left side view; and,
FIG. 4 is an enlarged fragmentary view from upper 4-4 to lower 4-4 in FIG. 2.
The broken lines defining the side wall 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 stippling form no part of the claimed design.