Indiana Code Title 9. Motor Vehicles § 9-19-4-3

Sec. 3. A vehicle with a frame or body that extends more than sixty (60) inches beyond the rear of the rear axle and is more than forty-two (42) inches above the roadway may not be operated on a highway unless the vehicle is equipped with a bumper on the extreme rear of the frame or body. The bumper must extend downward from the rear of the frame or body to within thirty (30) inches of the roadway and must be of substantial construction.