The ornamental design for an exteriorsurface of a rear wheel unit for a motorcycle to tricycleconversionkit, as shown and described.
FIG. 1 is a right side perspective view of an exterior surface of a rear wheel unit for a motorcycle to tricycle conversion kit showing my new design, the corresponding perspective view from the left side being a mirror image thereof;
FIG. 2 is a right side elevation;
FIG. 3 is a left side elevation;
FIG. 4 is a rear elevation view; and,
FIG. 5 is a top plan view.
The broken lines shown in FIGS. 1–5 are for illustrative purposes only and form no part of the claimed design.