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I wanted to install puncture resistant tubes on my mountain bike. Unfortunately the only size I could find were 27.5×.215 tunes and my tires are 27.5×.210. I got the tubes on, the beads seated and the tires inflated. I took it for a ride and intentionally hit some hard bumps, nothing happened. How big of a problem is the size difference? Should I expect these tubes to blow out or are they probably good?

Chris
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1 Answers1

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Assuming you mean a 27.5x2.15 tube in a 27.5x2.10 tire, that's a difference of 5 one-hundredths of an inch, or about 1 1/4 mm.

That's - not going to matter.

At all.

There'd be zero benefit in getting tubes that are labelled as exactly 27.5x2.10. There's even a good chance those "smaller" tubes would actually be larger in reality - tube sizing isn't critical down to the mm.

Andrew Henle
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    That's what I was asking, thank you! I was worried because it was harder to get the beads seated than with the OEM tubes. – Chris Jul 30 '23 at 21:55
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    Agreed - you can generally go 10% over the nominal max size, and 20% under without significant issues. This tube should be fine for 2.3" to 1.75", or 44-60 mm Puncture resistant tubes are probably thicker butyl rubber and just a bit harder to manipulate, or perhaps there's sealant inside the tubes too. – Criggie Jul 30 '23 at 22:28