A lot of old british cars have a 4" PCD on a 4 stud spacing. Imps, minis, other rootes and BL stuff. Fords were 4.5" I think.
The trouble with looking for wheels from those is that all the wheels will be ancient, and they'll tend to be in smaller sizes (a lot of cars ran on 10, 12 or 13" rims at the most). Might work for a trailer though.
For more you can refer to this site.
http://www.clubgti.com/showthread.php?229326-what-cars-use-4-inch-pcd