First off, I don't have anything to do with this site. I found it when looking for fitment for my Belair. After you go through vehicle selection you can then choose diameter if you want. Then they show available wheels/tire combos that they guarantee will fit. I used this to select diameter/width/offset to have some steel wheels made and also to select a tire size. I did double check with the tire mfg site to verify rim size and cross section and measured my car SEVERAL times. Pretty handy site.
http://www.rims-n-tires.com/rt_packages.jsp