Tyre sizes!

[lorenab3000]

Hello!
I hope some one out there knows! I am wondering excactly how the new tyre ISO system works? I have been trying to do a bit of research and know that it comes with 2 measurements, 1st the width of the tire or rim in mm and then the diameter of the bead seat of the rim. You see I need to find out a variety of bike wheel sizes but its hard to find a site that gives those details in an easily digestible way! Have tried the Sheldon Brown website and its gives a list of the ISO bead width but not the tire width? Why I dont know? For example its says a 26' x1 wheel is an ISO of 571mm BUT 26' is not the same size as 571mm? Confused! Would be great if someone could shed some light on this for me!
Many Thanks
L

 

[SatNavSaysStraightOn]

I thought that 26 inch was diameter, whereas 700c was actually imperial and circumference and is in fact 622 in ISO...
I could be completely wrong though

http://www.bikecalc.com/wheel_size_math
http://www.ctc.org.uk/cyclists-library/components/wheels-tyres/tyre-sizes

 

[lorenab3000]

The more I look into it the more confusing it is getting! I think there is a lot of different types of sizing and its my understanding that they are trying to introduce the use of ISO so that everyone is on the same page but nobody seems to use it! Bike Calc is quite helpful thank you!

 

[Rickshaw Phil]

The old style tyre sizing is really confusing as the sizes often aren't as described (a 26 inch mountain bike wheel is actually only 22 inches in diameter at the bead seat) and there is lots of inconsistancy (I'm aware of 6 different sizes called 20 inch which are all incompatible with each other).

The ISO sizing is definitely the one to use for simplicity and this PDF from Schwalbe gives the most comprehensive information I've found (including pretty much everything else you need to know about tyres).