Peter and Mike,
2 days ago I received 60+ pictures of a Pf.11 Pontonwagen, exhibited(!!!) in the Museum of Engineer Units in Svishtov,Bulgaria.
The tires of the trailer are Bulgarian, but the wheels are original.
The inscription of the tires(32x6-Д) reflects Bulgarian State Standard and corresponds to tire size 6,5x20:
I further checked the sizes for a 6,5x20 tire in the "Technisches Handbuch fuer Fahrzeugluftreifen-1939" and found that the width of a twin 6,5x20 wheel corresponds to the width given for the Pf.11 twin wheels in the Lone Sentry database:
Thus the right tire sizes for all Pf.10/11/12/13 trailers are:
Or in 35th scale-tire height of approx. 24 mm, single tire width of approx. 4,5 mm. while twin wheels width should be 10,5-10,6 mm.