Upon those streets or portions of streets that have been signed or marked for angle parking, no person shall park or stand a vehicle other than at an angle to the curb or edge of the roadway or in the center of the roadway as indicated by such signs and markings. When markings are present, all vehicles shall be parked within the designated spaces, as marked. Other than motorcycles, mopeds, or motorized bicycles, no vehicle shall be backed into a diagonal parking space. No part of any vehicle or the load thereon, when said vehicle is parked within a diagonal parking district, shall extend into the roadway more than a distance of sixteen (16) feet when measured at right angles to the adjacent curb or edge of roadway.
(Code of Iowa, Sec. 321.361)