The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing our new design, it being understood that the tread is repeated throughout the circumference of the tire, the opposite side perspective being substantially identical thereto, it being understood that the dashed lines form no part of the claimed design;
FIG. 2 is a front elevation view thereof, the rear elevation being identical thereto, it being understood that the dashed lines form no part of the claimed design;
FIG. 3 is a side elevation view thereof, the opposite side elevation being identical thereto, it being understood that the dashed lines form no part of the claimed design;
FIG. 4 is a section view taken on line 4-4 of FIG. 2 of a tire incorporating the tire tread of FIG. 1, it being understood that the dashed lines form no part of the claimed design; and,
FIG. 5 is an enlarged view of a portion of the tire tread of FIG. 2, it being understood that the dashed lines form no part of the claimed design.