Indiana Code Title 9. Motor Vehicles § 9-21-7-7

Sec. 7. (a) This subsection applies during the times specified in section 2 of this chapter.  Whenever the load upon a vehicle extends to the rear four (4) feet or more beyond the bed or body of the vehicle, there shall be displayed at the extreme rear end of the load a red light or lantern plainly visible from a distance of at least five hundred (500) feet to the sides and rear.  The red light or lantern required under this section is in addition to the red rear light required upon every vehicle.  Clearance lights or reflectors on vehicles that are being transported may be used to delineate the extension of the load in lieu of other lights required in this section.

(b) This subsection applies during all times not specified in section 2 of this chapter.  A vehicle described in subsection (a) shall display at the extreme rear end of the vehicle's load a red flag or cloth not less than twelve (12) inches square, displayed in a manner in which the entire area is of the flag or cloth visible to the person who drives a vehicle approaching from the rear.