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Can I mount 25mm tires on a rim designed for 26mm tires?

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Can I mount 25mm tires on a rim designed for 26mm tires?

Old 06-23-20, 12:16 AM
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SpeedyBlueBiker
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Can I mount 25mm tires on a rim designed for 26mm tires?

I've got about 3,300 miles on my road bike tires. It's the tires the bike came with when I bought the bike. They are 26mm tires mounted on carbon rims. When I started looking for 26mm tires there weren't many choices but a lot of choices for 25mm. Could I mount 25mm tires on the same rims or would this not work?
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Old 06-23-20, 12:22 AM
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caloso
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Yes.
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Old 06-23-20, 12:49 AM
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Yes is the answer. If you were looking for more information on wheel & tYre sizes Sheldon Brown's website is the place to visit.
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Old 06-23-20, 08:25 AM
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wgscott
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Sounds too risky.

Seriously, I think tire width tolerances are greater than 1mm. You will be fine.

But if it were me, I would be asking how wide a tire I could mount.
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Old 06-23-20, 08:30 AM
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aclinjury
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what's the INTERNAL width of the rim?
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Old 06-23-20, 09:25 AM
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Yes, but as mentioned, I'd be looking to go bigger if they'll fit the frame.
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Old 06-23-20, 10:14 AM
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Ross520
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Originally Posted by SpeedyBlueBiker View Post
I've got about 3,300 miles on my road bike tires. It's the tires the bike came with when I bought the bike. They are 26mm tires mounted on carbon rims. When I started looking for 26mm tires there weren't many choices but a lot of choices for 25mm. Could I mount 25mm tires on the same rims or would this not work?
As others have suggested, I think it would be advantageous to go UP a size rather than down. 28s will be quicker, as well as more comfortable. They're not any more expensive, either, so it's really a no-brainer unless they physically will not fit.
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Old 06-23-20, 10:20 AM
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Should be able to. I would just contact the company that makes the rims and ask. It will vary.
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Old 06-23-20, 10:29 AM
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ofajen
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FYI, here is a version of the ETRTO compatibility chart. I regard it as conservative and I’m guilty of going a bit wider.

https://bikerumor-wpengine.netdna-ss...ards-chart.gif

Note that the difference of 25mm to 26 mm doesn’t even register on the resolution of the chart. It’s a small difference.
Otto
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Old 06-23-20, 10:34 AM
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100% it will work.

The only two things to look out for are that the tire is at least a wee bit wider than the rim, and that the tire mounted on the rim will fit in the frame or fork. Going down one mm in width will be totally fine.

As mentioned above, you can also choose to go up in width - any tire labelled '700 X <width>c' or '622' can be mounted on your rim, but you will be limited by the tire clearance in your frame and fork.
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Old 06-23-20, 11:00 AM
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Originally Posted by ClydeClydeson View Post
... but you will be limited by the tire clearance in your brake calipers (if not a disc bike).
Could also be the limiting factor...
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Old 06-23-20, 11:03 AM
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Originally Posted by COYSpurs View Post
Should be able to. I would just contact the company that makes the rims and ask. It will vary.
No, do not do this. It will not vary. There is no rim that will fit a 700x26 that will not fit a 700x25. You can also fit a 700x23 and, as others have suggested, a 700x28 if the larger tires do not rub against your fork or frame.
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Old 06-23-20, 04:39 PM
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1) Actual widths vary widely compared to the width printed on the sidewalls.
2) Some BF posters would be shocked at how cyclists in the real world (CX'ers in particular) exceed recommended width limits
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Old 06-23-20, 09:46 PM
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Ross520
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Originally Posted by caloso View Post
1) Actual widths vary widely compared to the width printed on the sidewalls.
2) Some BF posters would be shocked at how cyclists in the real world (CX'ers in particular) exceed recommended width limits
If you read the rest of the those posts you'll see that they're just being facetious. 😁
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Old 06-25-20, 07:20 PM
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yes, no worries
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