Hi Charles, 'LBSC's Kingette and Purley Grange; Martin Evans's Nigel Minor and the Society sets the wheel back to back at 2 9/32" with a 3/8" for the wheel...
thanks Simon I had allowed 3/32 for the bogies ,, I will skim another 1/32 of that its just that 9/64 seemed a bit excessive not being familiar with this...