[bhhad25]

will this tire fit on a 650b rim? I know it's a little small, but just wondering if anyone's tried it.

http://www.bikemannetwork.com/biking/p/COMPTRCR/TR5122

 

[Cracked Headtube]

actually it would be too BIG. 27" etrto/ISO is 630mm while 650B is 584mm.

Check this out to help understand all these sizes:
http://www.sheldonbrown.com/tire_sizing.html

 

[bhhad25]

I just thought 650b was 27.5 inches. Didn't know bout all the differences, thanks for the link.

 

[Cracked Headtube]

The ISO is what you need to pay attention to when dealing with tire sizing.
Working in a shop you'll learn pretty quick.
Look on your current tires, you see what looks like a code. 26" MTB tire is 559 ISO, and the 559 is printed on most 26" mtb tires.
When dealing with tires you'll also learn that fractions and decimals do not transcend. 26"x 1 1/4 is WAY different than 26"x 1.25. The diameters are not the same.
I think we've got most things standardized, now.