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; and,
FIG. 4 is an enlarged fragmentary view thereof, taken from a section of FIG. 2.
The broken line showing of portions of the tire tread in the figures is included for the purpose of illustrating environmental structure and forms no part of the claimed design.