I think he's talking about the rust line on the actual wheels. And yes, brake rotors will rust when left in the rain. You don't need brake "wipers" to clean your rotors, brake pads do a pretty good job. Those brake wipers are meant for wet weather. I've actually driven race cars with brake "mist-ers" on them to cool the brakes. I have no idea what all this means that I'm typing, I must be out of it.