I just put on 20" wheels w/ Michelin PS2 255/30/20 Tires on my '07 Mustang GT Convertible. It looks great but now after last nights rain I noticed the brake discs are showing rust.......anything I can do to prevent or remove this.
The stock brakes will start to show rust 20 minutes after the rain. As others said, just drive it around the block. If you want to permanently prevent this, go get some larger aftermarket rotors that are plated to complement those larger wheels. No rust, and bigger brakes, how can you go wrong?
The more important question (to me at least), is why do you have a stock width tire on a 20" wheel? If I was going to spend the money on wheels, I'd definitely get some wider tires to help with traction a bit. Personally, that will be one of my first mods. I guess I'm just curious as to why.....