I'm trying to replace inner tubes on my bike but I got ones that do not match the one that I am taking out of a wheel.

  • We need to know what size your tyres are. – Carel Feb 7 at 10:02
  • @carel I'd guess the two sizes are in the title, but not which is which. – Criggie Feb 7 at 10:25
  • 1
    @Criggie : If we assume that both tyres are 25mm, then it will be OK. But not if they are both either 23 or 28. – Carel Feb 7 at 12:58
  • @Criggie Those are tube sizes, not tyre sizes. – David Richerby Feb 7 at 15:15

700 essentially refers to the diameter of the wheel, while the other two numbers give the range of tyre widths that the tube is suitable for. So 18-25 covers tyres between 18mm and 25 mm inclusive, while 25-32 would suit slightly wider tyres (25mm wide - 32mm wide inclusive) of the same wheel diameter.

So both tubes would suit a 700c x25 tyre as they overlap sizes there, but they aren’t the same per se

  • I've successfully used a 18-to-25mm tube in a 32 mm tyre. In theory its fractionally lighter but is more stretched. A wider tube in a smaller tyre runs the risk of pinching or folding on installation, yet will produce a slightly more puncture resistant wheel due to less stretch. Both to sharps and to snake bites. – Criggie Feb 7 at 10:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.