23mm tires on a 23mm rim, measuring 24.6mm - lower pressures?
08-31-23, 12:57 PM
#1
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23mm tires on a 23mm rim, measuring 24.6mm - lower pressures?
Trying to find a way to keep the 2011 Time NXR Instinct frame I just got. Seller said I should have no issue using 25mm tires - but the frame will not clear anything above 23mm.
Question is, if 23's measure 24.6mm on the C17 rim, would they behave more like 25's? Or would I still have to pump them up to 100 psi?
Question is, if 23's measure 24.6mm on the C17 rim, would they behave more like 25's? Or would I still have to pump them up to 100 psi?
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'11 Time NXR Instinct / '79 Paris Sport by Moulton
'11 Time NXR Instinct / '79 Paris Sport by Moulton
Last edited by AndyK; 09-01-23 at 11:45 AM.
08-31-23, 01:48 PM
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Personally I pump my tires up to the pressure that works best for me on the road surfaces I ride on. I really don't care what any tire pressure calculator says. If I get pinch flats, my pressure is too low. If the bike vibrates like heck going over chip seal roads, I have too much pressure. Just try out a pressures for 5 or 6 rides and then try higher or lower for another 5 or 6 rides. Keep trying different until you figure out what works best for you.
Just stay within the limits of the tire and rim if it has one. Other wise your low limits is the pressure at which you get pinch flats or can't handle sharp curves well or your high limit is when the bike is so uncomfortable to ride over bumps that you just can't stand it.
When we use to have chip & seal roads around here, I use to lower my tire pressure some when I was going to be on them for anything but a very short time. Most of the road here are smooth and with small aggregate in the surface layer. So I get away with running higher pressures than the tire pressure calculators give.
Just stay within the limits of the tire and rim if it has one. Other wise your low limits is the pressure at which you get pinch flats or can't handle sharp curves well or your high limit is when the bike is so uncomfortable to ride over bumps that you just can't stand it.
When we use to have chip & seal roads around here, I use to lower my tire pressure some when I was going to be on them for anything but a very short time. Most of the road here are smooth and with small aggregate in the surface layer. So I get away with running higher pressures than the tire pressure calculators give.
08-31-23, 04:41 PM
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Rim width? How much do you weigh? 2011 was about the time when bike manufacturers started getting sensible building their frames to provide better tire clearance. Back when I started riding, even pure race bikes had ample clearance for larger tires. I once built a set of 27" wheels for a friend who owned a Peugeot PX10. Even with the larger diameter wheels and the much wider tires there was ample tire clearance. I have never owned a bike that didn't have room for at least 700 x 25 tires. My Look 595 has enough clearance for 700 x 28 tires even though it was enough of a race bike that Thor Hushvold was able to win the final stage of the 2006 Tour de France on his
08-31-23, 06:57 PM
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Yes, you can lower pressure; wider is wider, regardless of whether it’s because the nominal tire size is bigger or because the rim has more internal width.
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09-01-23, 11:47 AM
#5
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My rims are 17mm internal, 22mm external Zonda C17's.
I weigh 184
I weigh 184
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'11 Time NXR Instinct / '79 Paris Sport by Moulton
'11 Time NXR Instinct / '79 Paris Sport by Moulton
Last edited by AndyK; 09-01-23 at 11:50 AM.
09-01-23, 12:54 PM
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You should pump them as if they were 24.6mm, not 23mm. So yes, closer to the recommend pressure for your rider+bike weight on a 25mm measured width tire (since I don't recall calculators going into decimals), maybe err on going slightly over.
09-01-23, 01:27 PM
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Zipp tire pressure calculator says 91/96
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'11 Time NXR Instinct / '79 Paris Sport by Moulton
'11 Time NXR Instinct / '79 Paris Sport by Moulton
, that was about what I'd run with 25s. Give it a go and adjust up or down based on feel.
09-02-23, 06:29 AM
#9
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Makes sense, since your 25mm tires on 15mm inner rims would measure the same as my 23’s, on a wider rim.
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'11 Time NXR Instinct / '79 Paris Sport by Moulton
'11 Time NXR Instinct / '79 Paris Sport by Moulton
09-03-23, 04:26 PM
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