The ornamental design for an aerodynamicbumper for a truck, as shown and described.
FIG. 1 is a right front perspective view of an aerodynamic bumper for a
truck showing my new design it being understood that the broken lines are
for illustrative purpose only and form no part of the claimed design;
FIG. 2 is an enlarged left front perspective view thereof; and
FIG. 3 is a greatly enlarged left side elevation view thereof.