How close must mudflaps on trucks or trailers be to the surface of the highway?

Mudflaps on trucks and trailers must be positioned within 8 inches of the surface of the highway. This requirement is in place to ensure that the mudflaps effectively serve their purpose in minimizing the spray of water, mud, and debris that can be thrown up by the vehicle's tires. Proper positioning helps improve visibility for other drivers and reduces the risk of accidents caused by reduced visibility in adverse weather conditions. The regulation specifies this height to maintain a balance between effectiveness and adherence to safety standards for road use.