The ornamental design for a tire tread, as shown and described.
FIG. 1 is a perspective view of a tire tread showing my new design, it being understood that the pattern is repeated uniformly throughout the circumference of the tread;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side perspective view thereof;
FIG. 5 is a right side perspective view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is a sectional view of line 8-8; and,
FIG. 9 is an enlarged fragmentary view from upper 9 to lower 9.
The broken line environmental showing is for illustrative purposes only and forms no part of the claimed design.