The ornamental design for a tread of a tire, as shown and described.
FIG. 1 is a perspective view of a tread of a tire of the present invention, it being understood that the pattern is repeated uniformly throughout the circumference of the tread; and,
FIG. 2 is an elevational view of the tread of the tire tread shown in FIG. 1.
The broken line showing of a tire sidewall and inner bead and the peripheral boundary between the tire tread and sidewall is for illustrative purposes only and forms no part of the claimed design.