Indiana Code Title 9. Motor Vehicles § 9-20-3-4

(1) a recreational vehicle may not exceed forty-five (45) feet;

(2) a vehicle used by railroad companies to transport steel rails in connection with a railroad construction, reconstruction, or maintenance project may not exceed forty (40) feet;

(3) a bus is subject to IC 9-20-8-2;  and

(4) a single vehicle equipped with permanently installed specialized equipment used for lifting, reaching, pumping, or spraying is allowed an additional five (5) feet for overhang of the equipment.  An allowable overhang may not be used to transport cargo.