It’s important that your wheels and brake rotors are cool to the touch when you clean them. Cold water can shock the hot metal of your brakes and wheels, causing serious damage. If your wheels are too hot, the cleaner can bake onto the surface and be difficult to remove. After a drive, wait at least an hour before you clean.
This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/articles/2007/03/15/cool-those-rotors