Exactly like aerosol hairspray! haha, but if you have big tires in the 33"+ expect to go through a can of that stuff every time you detail it. The McGuiars Tire Foam coats a lot more, but it does fling a little. I just drive it around for a day or two, then whipe off the 'excess fling' with a wet chamois.

 

I found using an applicator (from wal mart or auto zone) works the best for me. Its just a piece of curved foam and it keeps you from spraying too much on. It also keeps you from spraying it on your wheel and keeps you from having overspray get on your truck. Its only about $1.50 and well worth it imo. I use meguiars as well.