Try this link to loyalhannadockyard. This will take you right to the tires page. They have a ton of stuff through there and Don is really nice to deal with. I met him at the Toledo show, and was impressed. They look like they could be a little pricey to run all the way around a crew boat but they sure do look nice. I have a lot of left over tires from car model kits I used to build years ago but not enough to help you out though. If you should decide you want them let me know and I'll see how many I have and if any of them are the size you need. You can have them if they fall in the realm of what works for you ok.
Tim
sorry, I had to edit this, the first time I read your post I didn't catch the "really cheap" part of the tires question. If I come across anything else I'll post it for you ok.
http://www.loyalhannadockyard.com/BO...ER%20TIRES.htm