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