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I'm riding on 700x23c tyres with 700x23c tubes, road bike. I've obtained a box of 700x25c tubes. While I'm taking the approach that it's always best to fit the correct size, I'd like to either use, sell or give away these 700x25c tubes.

If I use them:

  • Will I encounter problems?
  • How soon will these issues occur?
  • What sort of problems may occur?

There is a similar question, although it deals with borderline issues, not explicitly with incorrect sizes.

What inner tube size to get for my road bike?

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    Usually tubes in that size range come with a range of suitable sizes listed, like 18-25. I'd think the difference in size between a 23 and a 25 definitely falls in the "borderline" area. If it's a "big" 25 tube and you have a "small" 23 tire, you might have some problems. Otherwise, I'd say it's likely you can use those tubes in your 23 tires with no issues. – Andrew Henle Feb 17 at 23:20
  • Thanks for you reply. I'm thinking that one problem I may encounter with a larger tube is when I inflate close to the tyres rated 120psi. I usually like to ride on 80-90 psi, so I won't be at the extreme. Would you or anyone else think that the tyre walls may have issues holding back an oversized tube? – norman_h Feb 18 at 0:27
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    90 psi is 90 psi. Again - as long as the tube isn't so stretched that it's prone to failure, or doesn't have enough room to expand smoothly and creates kinks/folds, the tube doesn't matter. The tube doesn't stop the air from expanding - the tire and the rim do that. The tube only stops the air from leaking through. The tube is nothing more than a balloon thick enough to withstand some rough treatment. – Andrew Henle Feb 18 at 1:25
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    Having a slightly over-sized tube will not cause problems with high inflation pressures -- so long as the tube is not so large as to fold up on itself inside the tire there will be no problem – Daniel R Hicks Feb 18 at 1:29
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    (Understand that the pressure "held" by a standard tube is miniscule -- five pounds at most. The tube has virtually no effect on the max pressure capacity of the tire.) – Daniel R Hicks Feb 18 at 1:30
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They'll be fine - I'd certainly use them without question in a 23mm tyre.

Most tubes cover a range like 18-25 and 25-38. Given 23 and 25 are in the same range I'd expect it to work correctly.

If you have access to a spare 23 and these 25mm tubes, compare them. I bet they're identical in size, or so close to it that the difference is immaterial.

Tubes are consumables, you'll use them up eventually.

Other options:

  • Stick one in your saddle bag as the last resort second spare.
  • Give them away.
  • Buy a 25mm tyre and try it out (if your bike frame can fit one)
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    @normon feel free to add your own answer - This answer is that they're essentially the same size, and there's no increase risk of folding. Its not like you're shoving a 40mm tube in a 25mm tyre. – Criggie Feb 18 at 3:39

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