I would just use when I parked, but sold on slidersno they are not, nothing on our trucks body is aluminum. but dont get them, they will destroy the paint, they will collect road debris and other "crap" and will hold it to the doors and they will get scratched. i saw this a lot when i was working at BMW/Mini, the Minis had these little magnetic door saver things and when you took them off you could see where they used to be, the paint was all scratches and showed a silhouette of them. bad idea if you ask me