I've got a bike tire that says "(32-630) 27 X 1 1/4" on it.

I've got also got an innertube that says "700X18/23C -27X1 A/V".

I'm trying to figure out if the innertube is the right size for the tire. I gather that my tire has a 27" diameter and a 1 1/4" width. It seems that the innertube is designed for a tire that's 27" by 1"... which seems like it's not the right size. But is that correct? Or will the innertube fit? And in either case, what does A/V mean in this context?

Many thanks,


  • That innertube would be slightly undersized -- it would probably work, more or less, but you might have a low spot (and a bump every tire revolution) in the valve area because the rubber is thicker there and doesn't expand as readily. Generally the tube's box will list the range of sizes it can accommodate. Aug 7, 2012 at 12:09

1 Answer 1


Schrader valve/Schrader tube

aka "American valve" or "Automotive valve"

alt text

The Schrader valve consists of a valve stem into which a valve core is threaded, and is used on virtually all automobile tires and most wider rimmed bicycle tires. The valve core is a poppet valve assisted by a spring.


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