People fit the 17" rim from an mc21 to get more tyre size options. You need to use the F3 style link plates to get the correct ride height though. Are dunlop alpha 12's not available in the uk? We can get them in Australia (as of 4 months ago anyway). I would have thought there would be a lot more 18" wheeled bikes sold in the UK as VFR400's were offically sold there weren't they?