The Mysterydesigns kit, will only accept c06 rims or their custom made rims ( very $$$ )
I have found a site that sells new aluminum co6 corvette style rims very very affordible, but to maintain the bike look I insist on using motorcycle tires. ( 250/40/18 ) on the 9.5" rims.

In speaking with Brian at Mystery and doing lots of research on the net, car rims are larger than motorcycle rims. leaving great risk to both the tire and the person mounting them. I am wondering if anyone has ever turned or milled down auto rims to mount motorcycle tires on them, I can not find the specs online as the actual size difference.

 

I'll ask around, but no I haven't come across anyone doing this.

Hack

 

There are shops out there that can cut down the width of your wheels, ask around a local speed shop.