Which of the following vehicles is exempt from requiring mud-flaps?

Mud-flaps are designed to prevent water, mud, and debris from being sprayed onto other vehicles and the roadway from the tires of a vehicle. Certain types of trailers, such as pole trailers, are specifically exempt from the requirement to have mud-flaps due to their design and usage characteristics. Pole trailers are typically used for transporting long, cylindrical loads, such as poles or pipes, and their configuration often means that the wheels are positioned in such a way that the splash and spray generated by the tires does not present the same risk as it does for standard trailers.

On the other hand, heavy-duty trucks, regular trailers, and commercial vehicles are generally designed and used in ways that necessitate mud-flaps to enhance safety on the road by minimizing the potential for debris flying off their tires. This is why those types of vehicles typically must comply with mud-flap regulations.