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Tubed vs tubeless tyre clearance?

Do lower pressures change the available tyre clearance for a given frame? For example, if a frame will take a 25mm tubed tyre at 100psi, could you potentially get away with a wider tyre at a lower pressure? Say a 27/28mm at 70psi?

Or is rim profile more important in determining actual vs nominal tyre width/height?

 

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BehindTheBikesheds | 6 years ago
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Depends on the tyres. These numbers from Bicycle Rolling resistance

25mm Pro one tubeless measured 24mm height at 100PSI and a measured width of 27mm on a 17mm internal rim. 

25mm michelin Pro4 at same pressure with butyl tube measured 25mm height and 28mm actual width.

25mm conti 4000SII, 100PSI/25mm height/27mm width

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kil0ran | 6 years ago
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I think this gets into "how much clearance is enough" territory too. I've squeezed 28s into my Triban 3 but it's very tight, particularly clearing the brake pivot in the fork. Will probably drop back down to 25s.

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peted76 | 6 years ago
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Higher pressures cause the tyre to expand. Lower pressure = smaller tyre (a little bit - not sure you could get away with an extra couple of mm). 

I'd suggest however that if you're clearance is that minimal then you should stick with the smaller tyre. 

I had an issue with a 25mm tyre at high pressure on a giant tcr frame.. I puctured and repaired it but it left a bulge in the tyre.. If I ran lower pressure, no problems whatsoever. Anyway I left it, forgot about it and on a hot day riding over a bit of warm tar managed to pic a stone up which got jammed into my frame.  I'd also had issues with claggy mud causing stones to jam in there also.

It's rare, but that minimal tyre clearance can cause issues. I run tubeless by the way.

 

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