The ornamental design for a rearfender for a motor vehicle, as shown and described.
FIG. 1 is a front perspective view of a rear fender for a motor vehicle of our new design, the opposite front perspective view being a mirror image thereof, with the exception of the door over the gas cap, which is not present on the opposite side;
FIG. 2 is an outer side view thereof;
FIG. 3 is a rear perspective view thereof, the opposite rear perspective view being a mirror image thereof, with the exception of the access door for a gas cap, which is not present on the opposite side;
FIG. 4 is top view thereof; and,
FIG. 5 is a rear view thereof.
The front, inner side and bottom views of the design are not part of the claimed design. The light portions of the motor vehicle shown form no part of the claimed design.