When are mud flaps required to be installed on trucks or trailers?

The requirement for mud flaps on trucks or trailers is specifically tied to the height of the vehicle in relation to the road surface. When a vehicle is 7 inches or more above the road, mud flaps become necessary as they help prevent debris, mud, and water from being thrown up by the tires. This regulation serves a safety purpose, as it reduces the risk of obscuring visibility for other drivers and minimizes potential damage to vehicles following behind.

In contrast, the other scenarios mentioned do not typically establish grounds for mandatory mud flap installation. For instance, a vehicle being in motion or towing another vehicle could apply to various road conditions and vehicle types, but the specific height criterion addresses the direct risk associated with greater clearance from the road. Additionally, carrying a trailer does not automatically necessitate mud flaps unless the specific height requirement is met. Therefore, the regulation focuses on the height requirement to ensure safety on the road.