Larger tires and pizza pans?

[hat_man]

Hello again,

I saw a young kid today with those really large custon tires/rims on an Impala. They might have been 18"-20" or so and it got me to thinking. The tires took up almost all of the room in the wheel well so that there was only about 2" or so between the tire and the fender. What would happen if you were to put "pizza pan" wheel covers on them? Would this make something akin to a wheel skirt not only on the rear but, as long as you are driving straight, in the front? Granted, some air space is there but wouldn't the majority of it be blocked off and create smoother air flow on the sides? Or am I just thinking outside the wrong box again?

Just a thought,

Hat_man