I've been searching on the web quite a bit for 20" wheels, too. I don't think new ones exist that will fit the AD trucks. Most of the new big truck wheels seem to be 19.5", 22.5", or 24.5", with much bigger bolt circles, and nobody seems to be making replacements for the old trucks. All I've found with the correct bolt pattern are the 19.5", both steel and aluminum, but as mentioned, the hub bores are too big, though that problem can be cured by using hubcentric rings to fill the gap. Also, there is the problem that they may not fit over the brake drums, as Scott mentioned above (for his '48). The rear drums on the 4000-6000 series changed in '51, though, so one would have to check if that makes a difference. Accuride makes the 19.5" steel OEM replacements that I found.
Sykotec, what is the bolt circle on the TF trucks with 22.5" wheels? Accuride makes a 6-hole, 8.75" circle, 22.5x6.75 steel wheel. They have a 6.5" bore, but are stud-piloted. Is this anywhere close?
