Will a 25mm tire be wider on a wider rim?
06-19-16, 11:23 PM
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Will a 25mm tire be wider on a wider rim?
I'm thinking about upgrading my Ksyrium Elites (21.5mm external, 17mm internal) wheels to an HED Belgium Plus wheelset (25mm external).
I use 25mmContinental GP4000II clinchers, and wanted to ask if anyone knows if the same tire will still be the same width or if it will be wider on the wider rim?
With the Ksyriums, there is little space space between the tire and the chainstays (about 1.5 to 2 mm on each side), so if the tire gets wider there is a chance it will rub.
Thanks!
I use 25mmContinental GP4000II clinchers, and wanted to ask if anyone knows if the same tire will still be the same width or if it will be wider on the wider rim?
With the Ksyriums, there is little space space between the tire and the chainstays (about 1.5 to 2 mm on each side), so if the tire gets wider there is a chance it will rub.
Thanks!
06-19-16, 11:28 PM
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Yes, but not all that much.
Figure that the most it could change is by 1/3rd the added rim width (based on the rim's added width adding to the circumference of the rim/tire combination).
However, it may not make a functional difference because on most bikes the closest part of the tire to the fork or stays isn't the side, but an area closer to the crown, and that doesn't move as much as the part closest to the rim
Figure that the most it could change is by 1/3rd the added rim width (based on the rim's added width adding to the circumference of the rim/tire combination).
However, it may not make a functional difference because on most bikes the closest part of the tire to the fork or stays isn't the side, but an area closer to the crown, and that doesn't move as much as the part closest to the rim
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06-20-16, 05:11 AM
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I've got those wheels, and the 700x24c S-Works Tubeless tires measure ~27mm wide on them at 90/f and 100/r.
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06-20-16, 04:21 PM
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Thanks for posting the above picture. I got new wheels and the rims are 1mm wider inside width that the old wheelset rims and the tires I was using (700x25) no longer work. They "just" clear the chain stays. I ordered 700x23 and looking at the above picture I think they'll be ok.
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06-20-16, 04:25 PM
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My HED Ardennes+ rims are 25.5 mm (HED says "25").
It might be a tight fit.
23c GP4000S are 26.8 to 27.0 mm wide. These work great. (as long as you have room on the frame!)
25c GP4000S are 29.0 mm wide.
On my old rims, about 18mm outside, the 25c GP4000S measured 25.5 mm.
On these wide rims, at my 170 pounds:
23c: 80-85 psi front, 95-100 rear
25c: 75 psi front, 88 rear.
Could probably go lower. I should experiment.
It might be a tight fit.
23c GP4000S are 26.8 to 27.0 mm wide. These work great. (as long as you have room on the frame!)
25c GP4000S are 29.0 mm wide.
On my old rims, about 18mm outside, the 25c GP4000S measured 25.5 mm.
On these wide rims, at my 170 pounds:
23c: 80-85 psi front, 95-100 rear
25c: 75 psi front, 88 rear.
Could probably go lower. I should experiment.
Last edited by rm -rf; 06-20-16 at 04:31 PM.
06-21-16, 09:33 AM
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There are so many posts about actual tire width on different rims, which of course is really helpful for getting an idea of whether the tire will fit. However, the height above the rim also matters, and that's more difficult to measure. On my frame I have 32mm of clearance from the top of the rim sidewall to the bottom of the seatstay bridge, which may be too tight for the 28mm version of the GP4000s even though I think that tire will clear the chainstays.
If the tire profile picture posted above is accurate, I am surprised that the tires get taller as well as wider on the wider rims. Can anyone explain how that happens?
06-21-16, 10:02 AM
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Of course it's not exactly a circle so it varies from tire to tire how much or even if it gets taller.
06-21-16, 10:39 AM
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If you think of the tire as part of the distance around the circle (that distance doesn't vary) and the rim as another part of the circle (gets longer with a wider rim) then the whole circle gets larger.
Of course it's not exactly a circle so it varies from tire to tire how much or even if it gets taller.
Of course it's not exactly a circle so it varies from tire to tire how much or even if it gets taller.
06-23-16, 10:52 AM
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Thanks for all the info!
Based on this I've decided to pass on the HED Belgium+, and I'm leaning towards the HED Belgium C2 model (23mm).
Anyone by chance has Belgium C2s with Conti GP4KII 25 mounted that can share how wide they are?
O borrowed a caliper to measure my current tires and they measure 25.5mm on my current rims. I'm guessing an extra mm would be OK, but more than that would be too close for cases like when/if the wheel comes out of true.
Based on this I've decided to pass on the HED Belgium+, and I'm leaning towards the HED Belgium C2 model (23mm).
Anyone by chance has Belgium C2s with Conti GP4KII 25 mounted that can share how wide they are?
O borrowed a caliper to measure my current tires and they measure 25.5mm on my current rims. I'm guessing an extra mm would be OK, but more than that would be too close for cases like when/if the wheel comes out of true.
06-23-16, 11:54 AM
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25mm Conti GP4000S II on Zipp 303 Firecrest are 27.9mm wide.
06-23-16, 12:32 PM
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Well, you do get the basic idea? The wider the rim, the higher the pressure - the wider your tyre will be. Since the rim's tyre bead is a part of the circle the tyre makes. As far as exact measures go, you'd have to do your own measuring. Especially since not all the 28 mm models are exactly 28 mm.
