This is a pretty old thread, but I thought a small update wouldn't go amiss:
The wheels that Roy von Doorp supplied and the set he re-tyred for us have been great, one set has gone now as I sold the engine with the trolley.
The other set is still in use on our Ruston engine, and the original set that we modified with strip rubber tyres we still have in the workshop.
Our trailer that we take the engine to shows in:
Peter