The ornamental design for a tread portion of an automobile tire, as shown and described.
FIG. 1 is a perspective view of an automobile tire, it being understood that the tread pattern repeats uniformly throughout the circumference of the tire.
FIG. 2 is a front elevation view thereof. A top plan view and a bottom plan view are identical with the front elevation view.
FIG. 3 is a rear elevation view thereof.
FIG. 4 is a right side elevation view thereof.
FIG. 5 is a left side elevation view thereof.
FIG. 6 is an enlarged fragmentary front view thereof; and,
FIG. 7 is an enlarged cross-sectional view thereof taken along line 7-7 in FIG. 6.
The portion of the article shown in broken lines is for illustrative purpose only and forms no part of the claimed design.