for thenewguy Mud flaps are located behind wheels, and the devices you refer to are for aerodynamic purposes. They are hard plastic, do not yield upon impact, and can be broken by almost any sort of road debris. Separated tire treads, mostly from recaps on trucks, are often the culprits but any old piece of **** will do. They are easily replaced, and can be ordered from your dealer for about $25. I have also repaired mine (several times), using epoxy glues, and fill gouges or cracks with black seam sealer, available ay any marine supply house. My road junk seems to favor the passenger's side. Maybe I'm unlucky, or just careless, but don't you despair-it ain't no biggie.
Marty