The ornamental design for a tire tread, as shown and described.
FIG. 1 is a partial perspective view of a tire;
FIG. 2 is a partial view of a first side thereof;
FIG. 3 is a partial view of a second side thereof; and,
FIG. 4 is a front view of the full tire.
The broken lines and the regions therebetween defining the inner bead and the sidewall depict subject matter that forms no part of the claimed tire tread design, and are included for the purpose of illustrating the full tire. The tread pattern is understood to repeat throughout the circumference of the tire.