The ornamental design for a tire tread, as shown and described.
1. Tire tread
1.1 is a right side elevation view of the tire tread showing my new design;
1.2 is a perspective view thereof;
1.3 is a front elevation view thereof;
1.4 is an enlarged partial front elevation view thereof, in which the area of enlargement is indicated by the reference markings 1.4-1.4 in view 1.3; and
1.5 is a left side elevation view thereof.
The even broken lines showing the sidewalls of the tires are provided for the purposes of illustrating environmental structure and forms no part of the claimed design. The dashed-dot broken line in view 1.3 are provided to illustrate the area of enlargement shown in view 1.4 and also forms no part of the claimed design.