Thanks, Guys! Scott, the tires came from AMT IH Payhaulers. I'll get some size reference pictures on here later, 9W. Please, do whatever it takes to get your friend to post and share his crane!
Here's kind of a size ref shot. That's a 1/25 dodge van based service truck next to it here.
This is an older picture. The frame has been shortened about 2 inches between the wheel bases since this pic was taken, and that black box containing batteries and controls has been shortened too.