I was thinking about the old carrier bikes when I was out riding* so I thought I’d Just resurrect this thread.
I vaguely remember that those rims were different from the other 26″ rim sizes of the day (1 3/8″ and 1 1/4″).
I remember trying to build a bike with the fattest tyres possible about 40 years ago for bush bashing in Oz. I was trying to chase up a set of those rims because of the 2″ tyres, but they were described as an American size and not available there (in Oz).
If so, then it is likely that they may be the same as the current mtb sizes. Tyres wouldn’t be a problem then.
It’s worth checking – easy enough to do by running a tape measure round the circumference of the bead seat and comparing them to an mtb one.
If they are 559mm, I’d like to know.
*Planning a retro fatbike to make up for my shaming at the retro ride in Aviemore…
Edit: quick visit to Sheldon proved me wrong.