Everybody else pretty much told you the right stuff about the rims - and it isn't illegal to run them. It's just illegal for a tire shop to change them without the proper equipment. Just go to a big truck shop, they can take care of it for you.
You can get new rims made up for you in a couple of places if you want to. Stockton Wheel, Vintiques and others can make custom one piece wheels that will fit modern radial tires. They can build to any tire size, so you could even run Semi-truck tires if you want (probably cheapest). The basic steel wheels are not that expensive, probably the same as for custom wheels at any tire store.
