In the getty photos, the car in the back has water covering about 3/4th of the tire! 18 to 20 inches tops.
http://editorial.gettyimages.com/source/search/imageResults.aspx?s=ImagesSearchState%7c0%7c0%7c28%7c0%7c0%7c0%7c1%7c%7c%7c0%7c0%7c0%7c0%7c0%7c0%7c0%7c0%7c1%7csean%20penn%7c0%7c0%7c0%7c0%7c0&p=1&tag=1