The vehicle tire and wheel idea has been around for a long time. William Rake came up with a version and plans for one he called "The Simple Saw". His home page no longer exists but you can still purchase plans at this link http://www.diyhomemadesawmill.com. Never ordered them so can't comment on the quality.
Many people have built this plan over the years, and there are many pictures of successful builds around the web. This 78 page pdf is a compilation of many of these pictures and a couple of information articles on blade maintenance.
High on my list is a mill build as well. I will be using the wheels and drive parts from either a 20" Delta or a General bandsaw. I picked them both up for scrap value many years ago. The General wheels are preferred because of their huge cast iron weight to power through the tough spots, but I would still hope to rebuild that saw. The Delta wheels are lighter alloy aluminum but the tires are still like new and I have dismantled the saw frame since it was beyond rebuilding. Still thinking about it, lol.
So to download 78 pages of bandsaw mill pictures click Vehicle Wheel Bandsaw Mills. 7 MB - pdf