How universal are inner tubes?

[Chris S]

How universal are inner tubes?

Could you use an MTB inner tube in a 26 x 1 3/8 tyre?

I realize the tyre sizes are completely different but the inner tubes both inflate to a 26 inch diameter.

 

[Davidc]

I think they're very forgiving.

I put an old 27" x 1 1/4" one in a 700c 35 tyre when I only had that available, and it was still there 6,000 mile later. I've also accidentally (when a bit drunk) put a mtb 26"x1.5" in a 700c 32 tyre. realised a few weeks later when I couldn't find the 26" tube to take on a trip. Didn't seem to do any damage.

 

[ufkacbln]

There is a fair amount of latitude, but the problem is fitting.

For instance the Schwalbe 12A is a 559 tube that will accommodate between 25 and 40 mm width tyres. The 13 will accommodate 40 - 62 mm widths

You could use either, but stufffing all the extra rubber of the larger tube into a 25 mm tyre is time consuming and increasing the likelihood of catching the tube when you replace the tyre.

I have prefer the lower ones and all my tubes are 12A even though my Tyres on the Thorn and Catrike are are in fact 50 mm

 

[GrasB]

As a general rule Up sizing tends to work, down sizing usually is where the issues come into things. Push things well out side their limits & puncture resistance & air loss can become issues.

 

[tyred]

I've done this. The biggest problem you'd have is that 26 x 1 3/8" is noticeably bigger than an MTB wheel and it will be tricky to get the tyre on without the tube popping out or getting stuck under the tyre bead. Once it's in, it'll be fine. I don't consider tube sizing to be an exact science as they will expand to fill the space they are in. Try inflating one fully outside of the tyre and it will be several times the size of the tyre (or it will bust!).

 

[Chris S]

The biggest problem you'd have is that 26 x 1 3/8" is noticeably bigger than an MTB wheel and it will be tricky to get the tyre on without the tube popping out or getting stuck under the tyre bead.

I thought there might be a catch!

 

[Sheffield_Tiger]

It's a common misconception and quite an understandable one, that a 26x1.25 must be the same as a 26 x 1 1/4 qand a 26x1.5 can only be a fraction off a 26x1 3/8 (almost 1 1/2). in an emergency though - fitting an MTB tube into an old 26" tyre with care is far better than the other emergency method of stuffing it with grass (I know this having ridden from Whitby, up Blue Bank, to Goathland on a grass-stuffed tyre)

I remember years back being grumbled at as if the labelling were my own fault when a customer brought back a pair of 26x1.5 MTB tyres that he'd bought to fit his Raleigh Chiltern (bought off the peg BTW not sold knowing what it was intended for). The old fella gave me a right old ear-bending