I've got a BRC Suburban that is in desperate need for new tires but I can't figure out what tire size these are. A tape measure pulls 603mm from outside to outside (which may not be deadly accurate because of the hub). I guess the ISO standard is from bead set to bead set but I don't have the tires off at the moment. I would assume that would be 5-10mm smaller. There are a lot of obscure tire sizes in and around that size.
I kind of feel like it is a 590 iso tire > sheldonbrown. com/harris/tires/590. html