The ornamental design for a tire tread, as shown and described.
FIG. 1 is a side perspective view of a tire tread showing my new design, it being understood that the tread pattern is repeated throughout the circumference of the tire tread, the opposite side being the same as that shown;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a reduced scale side elevational view of the right side thereof, the opposite side being identical thereto; and,
FIG. 4 is an enlarged fragmentary perspective view thereof.
The broken lines defining the tire sidewall and inner bead are for illustrative purposes only and form no part of the claimed design.