Tire size plzz

Got a guy here with a 2004 V-6 and wants to install some 20" on it. Do any of you have tthis size wheels on your Stang. If so what is the tire size.
Dont bash me on the size im just helpn a fellow out. I particulary dont like them. but anyway..............
 
I run a 285/35/18 on my car -- which is 25.85in tire height if I figured it correctly. Something like a 275/30/20 might work -- 26.49in tire height. From personal experience, I know a 25.85in tire gives just barely enough room for me to squeeze my scrawny hand (6'1 150lb) behind the wheel when the steering wheel is fully locked in either direction.

If its what the guy really wants, then I guess do your best, but it seems that its either going to rub or give such a tiny side wall that might make the wheels prone to curb rash -- assuming its 20x9. If it's 20x8 slap a 255/30-35/20 or 245/30-35/20 on there and it should be alright.