I bought an inner tube for my Brompton today but didn't have my reading glasses.

[Fastpedaller]

This sounds crazy, but bear with me . I bought an inner tube for my Brompton today and just about read ETRTO size as 47-355. I joked with guy behind the counter that I was looking for a 47-355, but could cut and rejoin it to get rid on the 6mm difference. It was only when I got home and changed my contact lenses to varifocal glasses that I noticed it says 18 x 1.75on the box. I suspect it's not a problem, but does anyone know if it will fit my Brompton?

 

[Fastpedaller]

Oops, my second error, as i should have been looking for 37 not 47. So not good.
Should have gone to specsavers.

 

[T4tomo]

very difficult to work oiut what you have bought, but a Brompton tyre is 16"x 1.35, ERTo 35-349 . the bold being the important measures.
if your bought an 18" tube then you've cocked up, is its erto 355 then youre OK - that like the old 27" to 700c - it matters for a tyre, close enough for a tube.
edit you might be OK, the 355 etro 18" looks like a weird 18" than is close to a brompton size despite 16" and 18" not being close!!!
https://www.sheldonbrown.com/tire-sizing.html

 

[brommieinkorea]

It might fit, but you're gonna have a heckuva time jammin' it in there.

 

[Fastpedaller]

Yup - I've spoken with the guy in the shop and he said they might have 16 inch tubes in the delivery tomorrow. -of course that depends on what 16 inch they are, but I'll make sure I have my glasses.
If I had a roadsite problem it would possibly get me mobile, but I may as well get the correct size as there's no urgency.

 

[gom]

Yes, check the ERTO. 20ish years ago I was wanting a 16” x 1 3/4 tube for my Brompton, and bought a 16” x 1.75. Hadn’t read Sheldon then so expected them to be that same size. It wouldn’t fit 🙄