Only Special Vehicle Combinations (SVC), which means truck-tractor and triple trailers, are required anti-spray devices in accordance with KAR 36-1-31.
(l) Antispray devices. Antispray mud flaps shall be attached to the rear of each axle except the steering axle. Mud flaps shall have a surface designed to absorb and deflect excess moisture to the road surface.
However, truck-tractors are required retroreflective sheeting (“DOT tape”) on the lower rear of the vehicle, which may be displayed on the mudflaps, mudflap brackets, or on the rear of the cab (49 CFR §393.11).