Hey Jim, From my understanding, any two or three piece wheel is considered a split rim. I just replaced all six tires on my '48 6400. The split rims are not illegal here. I had mine done at a big truck and heavy equipment tire supplier....T&W Tire. A lot of shops have gotten away from doing them because they are very labor intensive, plus they can be dangerous if not mounted up correctly. I don't know whats in your area, but check out the major suppliers like the one I mentioned above and also don't forget about the rural shops that do farm equipment. A LOT of pre-1988 farm trucks with 20" wheels are on the job. They have to have their tire work done somwhere.
Another thing Jim....If you do search out some rims Make sure of the rim width, because if you wind up with rims off of a 4400 truck and try to mount up some 8.50 or 9.00 series tires, they don't like to go on. Espesially the 9:00 tires. You cant get the split rim back together.
I have 9.00x20 tires on my 6400 and they just fit the rims, and they really fill up the front wheel wells. I got a very good deal on them, $800 with flaps and tubes & mounted. They were almost new take offs, still had the little rubber spikes on them. They don't rub the fenders but 8.25 or 8.50 tires would have been a little better fit, but new they would have been around $1200
