The total width of outer edges of front fenders, measured at the fender line, shall exceed the total width of front tires when wheels are in a straight ahead position. Front fenders shall be properly braced and free from body attachments. The chassis manufacturer shall provide a metal or fiberglass fender extension or flap to extend downward to the lowest edge of body. Openings in the floorboard or firewall between the chassis and passenger carrying compartment, such as for the gearshift lever and the auxiliary brake lever, shall be sealed.