A school bus shall be equipped with spray suppressants or mud flaps when the angle formed by the intersection of a line on the level road surface projected rearward from the point where the rearmost tire contacts the ground and a line projected from the point where the rearmost tire contacts the ground to the bottom edge of the rear bumper exceeds 22 1/2 degrees.
N.J. Admin. Code § 13:20-50B.34