I have four 6-lug rims from a Toyota Tundra pickup truck laying around taking up space. A friend upgraded at the dealership, threw them in the bed and I bought them for the tires which are now on my wife's car. They are 16-inch with a 5.5in bolt pattern. There are no center caps. $10/each if you want to pick them up. Would also consider some interesting (not necessarily rare or expensive) frags, live rock or livestock in trade. Trying to set up another tank. I can't help it. If you think you want them and that you might have something I'd be interested in, don't be shy.

They look like the item below (which is not an ACTUAL picture of the ones I have)

http://i3.ebayimg.com/07/i/000/cf/35/a5f4_1.JPG