Yeah, the cheapest route is the 15 that matches the diameter.
You could hit up ebay for single wheels...sometimes they have some on there, like this for example...
http://cgi.ebay.com/ebaymotors/20-CH...Q5fAccessories
They can sometimes be reasonable...then find a used tire at a local shop and you aren't in too deep.
I am pretty sure Dodge Rams 20 inch spare steelie fits as well, for a "true" 20 inch spare. Seems they are becoming pretty popular these days though for guys wanting to run over-sized steel rims, so I am not sure how easy they would be to find. Could call some wrecking yards, tire shops, or even dodge dealerships in the area. Somebody on here has a bagged project that they are using those wheels on...I believe....
Or just get AAA...they come pick you up on a flatbed!
