The ornamental design for a tread portion of an automobile tire, as shown and described.
FIG. 1 is a perspective view of a tread portion 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, a bottom plan view and a rear elevation view are identical with the front elevation view.
FIG. 3 is a left side elevation view thereof, a right side elevation view is identical with the left side elevation view.
FIG. 4 is an enlarged fragmentary front view thereof; and,
FIG. 5 is an enlarged cross-sectional view thereof taken along line 5—5 in FIG. 4.
The portion of the article shown in broken lines is for illustrative purpose only and forms no part of the claimed design.