Heated the tyre up to 700c and the rim burst into flames!

I hope the short grain in the middle of those shafts can take the strain.. for your sake and the horses'..

Well spotted. Didn't expect anyone to notice! There was little enthusiasm to build any steaming jigs, particularly as the shafts are primarily for show. If you look on the image of the wagon with 4 wheels, you will see that we have made a towing bar. A number of locals have 'retro' tractors and these will be used to pull the wagon, if it is to be used seriously. If we can get any shire horse horse owners interested, it will only be to hitch them up, and possibly pull along a 'hard core' fire road, with either no load, or a token log.

On your recommendation, I have now read the book with interest. I am sure the wheelwrights would be turning in their graves if they inspected our build in detail.
As you previously mentioned 'short grain', I will point out that the spokes in particular should have been 'cleft' to avoid that weakness. I have cleaved a fair bit some years back as another project, and used the pieces to build a fence for a local organic farmer, as seen in the image. The wagon is primarily for show, and the wood blanks were generously donated by Whitmores near Hinckley, so were too tempting to use.

Yeah I seem to remember Sturt saying they sawed out the shafts. That surprised me as I'd have thought it would be difficult to find young Ash trees in the forests that had not grown into just the sort of subtle curve that would be ideal for this purpose? Maybe there was a durability issue with 'green' timber..