Great set of 4 century-old portable steam engine wheels. These came as a spare set with a Massey portable steam engine I bought about 20 yrs ago. I had plans but never ended up using them. These would be great for a cart for an oil field engine build or your steam engine restoration project. They are 36" across and VERY HEAVY offered as I got them what you see is what you get. 
I am happy to answer any questions you may have.