The ornamental design for a tire tread, as shown and described.
FIG. 1 is a side perspective view of my new tire tread;
FIG. 2 is a front elevational view of my new tire tread of FIG. 1;
FIG. 3 is a side elevational view of my new tire tread of FIG. 1;
FIG. 4 is another side elevational view of my new tire tread of FIG. 1 from the side opposite that of FIG. 3; and,
FIG. 5 is an enlarged fragmentary view thereof.
The broken line showing of portions of the tire in the figures is included for the purpose of illustrating environmental structure and forms no part of the claimed design.