Most people don't have to deal with the wide range in tyre sizes we do at our co-op as we see everything from the common to the obscure and try to hold on to those rare / obsolete rims / tyres in the event someone might just need them and stock a pretty wide range of tyres... or will order them in for people as many obsolete tyre sizes are still in production but rarely stocked by mainstream shops.

Confusion abounds and the best way is to use the xx - xxx system as then you have a high probability of matching tyres and rims.

With fractional wheels and tyres still in wide useage this adds a little more confusion to the mix as there are so many 26 inch sizes out there it can be easy to make errors.

I use three different 26 inch sizes on my bikes and none are interchangeable as they are 559, 590, and 597 but all say 26 by x where several are fractional and the rest are the more common mtb standard of xx-559.

I now run 7 different rim sizes and used to run an 8th when I had a British roadster with 28 by 1 1/2 tyres (635mm)... Canadian roadsters also ride on a 28 by 1 5/8 by 1 3/8 which is really an xx-622.

Anyways... everyone seems to have a happy place when it comes to tyres and your size, riding style, and what you carry will also have an effect on what tyres work best.

When I mountain biked a lot I always ran a narrower than usual as at my weight the 2.3's that people were running just resulted in too much float and drifting whereas a narrower tire gave better contact pressure and traction.