Even though i pumped in air , there is noticable noise and sponginess when the tyre rolls. Since its my daily commuter, i cant risk facing frequent flats too.

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    Hi, welcome to bicycles. Most tubes are rated for a range; what was the range on yours? (e.g. "28-35")
    – DavidW
    Nov 7, 2023 at 16:22
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    Noise when rolling can also be the bead not being seated properly. Go all the way around the rim on both sides and check that the tyre edge position looks the same everywhere.
    – jpa
    Nov 8, 2023 at 8:47
  • @DavidW The upper limit was 35 as i recall vaguely.Nevertheless, i pumped up more air than before and the ride has become smooth and good like with the previous tube.
    – Nova
    Nov 9, 2023 at 17:21

1 Answer 1


Any increase in puncture risk from a fitting a 38mm tyre with a tube rated for 35mm (max) is tiny. Don't worry about it.

The softness you're feeling is probably simply that you haven't pumped it up enough. If you have a pump with a gauge, you can check either the recommendations on the tyre (between the minimum and the maximum, closer to the maximum if you're heavy) or a calculator online. If you don't have a gauge squeeze the tyre with your thumb against the rest of your hand. It should give very little. Noise when rolling is probably from the tyre deforming too much - again because it's not pumped up enough.

If you only have the sort of pump you'd carry on the bike with you, with no gauge, it's almost certain you haven't put enough air in. Pumping up fully with one of those takes more time and effort than you think.

I have, once, used a tube for max 38mm in a 51mm tyre. It got me home (I'd picked up the wrong spare). I've also bought 2nd hand bikes with 26" tubes in 700c wheels, and 24" tubes in 26" wheels.

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    In the early 2000s, I used to run 19-23mm tubes in 33mm cyclocross tires. I obviously survived the experience.
    – Weiwen Ng
    Nov 7, 2023 at 17:38
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    +1, rubber is really stretchy! You can get away with much bigger size discrepancies. Nov 8, 2023 at 17:08

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