First, there are mud flaps and there are rock guards. Mud flaps go behind the wheels. Rock guards go across the rear of the coach on the back end. We have met many long distance RV folks like ourselves that have removed the rock guards and installed mud flaps because the rock guards caused more damage or issues than the mud flaps. Not to mention dragging on the ground and getting damaged themselves pulling in and out of gas stations park entrances and other areas that have a "dip". We pulled ours off and tossed it away about a year ago. I added my own mud flaps behind the back wheels. We have just crossed 10,000 miles on this trip towing the car behind us and so far, absolutely no damage or issues using just the mud flaps. The car is going to get dirty no matter which you decide to use. Chuck