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Using the incorrect size tube
Due to the lack of availability on quick notice, I have had to use 700x25 tubes instead of 700x23 tubes on my bike.
I inflated the tire to only about 60 psi for fear of overinflation with the larger tube. What kind of issues will I run into running the larger tube? I usually inflate to 115psi with the smaller tubes. Is there a pressure I should aim for with the large tube? I am sure I could do the calculation, but I was hoping you folks could help out. Thank you |
No problem.
Most tubes have a range like 700 X 18- 25 |
Adirtytoilet, Most tubes are made to fit a range of tire sizes. You should be able to inflate as normal.
Brad |
In theory, a thinner tube in a wider tire will leak air a tad faster on account of being stretched more. A wider tube in a thinner tire will be more prone to getting pinched under the bead during assembly.
Overinflating is a factor of pump application - nothing more. A tube will simply stretch to fill the available space, it has no significant structural strength by itself anyhow. |
No adjustment or calculation required, just use your usual inflation pressures.
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I use mismatched tubes all the time. LIke I am currently using a 700 x18-23c tube in a 700x28c tire with no problem. I use tires slightly bigger than the tubes all the time.
I willgo the opposite direction but that means mounting the tire is usually a pain in the ass. If I have a 700x25c tire and try using a tube made for a 700x28c to 700x32c size, it will be a devil to mount but once mounted, it works fine. I have no problem inflating to tire's rated PSI ratings when using mismatched tubes. Its not so much the tube but the tire that holds the pressure in place. |
I almost exclusively use undersized tubes; a 700X18-25 tube is smaller than a 700X28-35 tube, not to mention easier to install (very little chance of it getting stuck under the bead). All my bikes have an undersized tube in their tool kit. It turns out that the only time I change my tube is when I get a flat on the side of the road. If I'm building up a wheel from scratch, I'll use the right size tube, but that's about it.
It hasn't given me a bit of trouble, not even the 700X18-25 tube in my 45mm hybrid tire. |
Just for fun put a lot of air in a tube by itself. It expands to 3 feet in diameter and 6" wide. There's no way a tube inside of a 700X23 or 25 tire makes any difference with sizes.
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The rim and tire bead will hold the tube in up to the tire's or rim's limit.
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Oversized tubes are ok to use with exception mentioned above about easier to pinch and harder to stuff in casing if much larger than called for.
I even heard you can use (and did this once years ago in a pinch) a 700c in a 26" but there will be a fold and a lump. |
make sure there is no tube under the bead.. all between them.
a 23/25 difference is insignificant.. a 23 in a 32 will have to balloon out to fill the volume, expanding thins the tube wall, so needs pumping a bit more often, as air weeps thru the pores of the thinned rubber.. |
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