OP -- The posts above are what I would try first (if it were me looking ... and I was once ...)
If you are around farms, look for whoever does tractor and equipment tires (they probably do commercial trucks, too). Not only will they probably be able to find those tires for you, they also will know how to work with multi-piece wheels. If you are around more non-rural areas, look for who ever does big/commercial trucks.
If you do buy tires online and have them shipped, you will still need to find one of these places because very few, if any, of the retail/chain tire centers will work with multi-piece wheels.
ljblue -- if that was your biggest investment in the truck, then wait until you have to have the truck painted ... or the engine rebuilt ...
You'll need a high-capacity magazine for the ole dollar gun ....
