Fitting thread rubbers will not cure your problem. They protect only the horizontal part of the wing, and most likely the scuffs occur where the wing curves down towards the ground, i.e. lateral to the rubbers. I have them and dislike them. They look good, but are water traps and a nuisance for washing and polishing. I wound never have fitted them if the car were bought new. If you still choose to do so, be sure that bolts and nuts are non-corrosive (SS + for instance ACF 40 or alternatively nylon). The OEM ones that are used for fitting are terrible, rusting to pieces. If you look at a car with thread rubbers of a certain age, you will often see small bulges along the rubber. Lift it up and you will see the rusty remnants of a small bolt. As suggested above, I tell my passengers to take care and lift their feet well over the wing.
