The ornamental design for a tread portion of an automobile tire, as shown and described.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
FIG. 1 is a perspective view of a tread portion of an automobile tire showing my design;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof; and,
FIG. 4 is a right side view thereof.
The portions of the tire shown in red are not being claimed, and thus form no part of the claimed design.