Right, thanks, Terry. I now realise (doh) that these are quite different 'split rims' to the ones on my wire-wheeled 1928 GB. I have to separate and remove the entire rim on one side, after which it's an easy task to slip the tyre and tube off. Btw, I have a new set of 600x20 tires but will be in need of tubes. Anyone know a good source, please? Cheers, Brian.