Whats the narrowest recommended tyre you can fit on a flow rim? It has an internal measurement of 22.6mm and is there a formula which you can use to work out the minimum and maximium tyre width rather than peoples guesstimates?

http://www.schwalbe.co.uk/pdf/techinfo.pdf

Thank you. Took a while to get my head round that at this time of night but think i've got the hang of it. 700x45c is the narrowest tyre I can use and still be ok.