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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
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    @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
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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

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