The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread.
FIG. 2 is a front view thereof. Top and bottom plan views thereof are identical to the front view.
FIG. 3 is a rear view thereof.
FIG. 4 is a left side view thereof.
FIG. 5 is a right side view thereof; and,
FIG. 6 is a view of the section thereof between the lines 6-6 provided in FIG. 2.
The broken lines illustrate environmental subject matter only and form no part of the claimed design. The dash-dot-dash lines indicate a boundary of the tire tread and are not themselves an element of the claimed design. The stippling and surface shading lines in the drawings depicts the character or contour of the surfaces represented and form no part of the claimed design.