The ornamental design for a tread of an automobiletire, as shown and described.
FIG. 1 is a perspective view of a tread of an automobile tire showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a fragmentary enlarged front view showing the details of the tread portion surrounded by line 4-4 in FIG. 2; and,
FIG. 5 is a section view taken along line 5-5 in FIG. 4.
Broken lines in the drawing figures are intended to show portions of the tire that are not being claimed, and thus form no part of the claimed invention.