# 23mm on 25mm rims



## jchau (Jul 16, 2012)

I have a 2005 Cervelo Soloist (yes getting old) and I want to get some compare wheels but it looks like most wheels are moving into the 25mm width size which Cervelo has told me I cannot or would not recommend 25mm tires for clearance issues. 

I know there have been a few older post about 23mm tires on 25mm wide rims. And in general it seems like you can run 23mm tires on 25mm wide rims. I guess have there been any updates on if you should or should not run 23mm tires on 25mm rims? 

Based on this image from HED it seems like 23mm would be a good option in terms of the aero budge but that is assuming running GP4000 (which I am not and I think Conti are a little bigger in size). 








Also what is a safe limit for inner width for 23mm tires? I am looking at rims with this profile which has 18mm internal vs 16mm for typical 23mm width rims.


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## Kerry Irons (Feb 25, 2002)

jchau said:


> have there been any updates on if you should or should not run 23mm tires on 25mm rims?
> 
> Also what is a safe limit for inner width for 23mm tires? I am looking at rims with this profile which has 18mm internal vs 16mm for typical 23mm width rims.


Not an issue in any way. You can put pretty wide tires on pretty narrow rims and pretty narrow tires on pretty wide rims. Your proposals are no where near "the edge" of compatibility. 

Some might argue about optimal matches, but even that is getting off into the weeds compared to real world riding on the road.


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## jchau (Jul 16, 2012)

Kerry Irons said:


> Not an issue in any way. You can put pretty wide tires on pretty narrow rims and pretty narrow tires on pretty wide rims. Your proposals are no where near "the edge" of compatibility.
> 
> Some might argue about optimal matches, but even that is getting off into the weeds compared to real world riding on the road.


Thanks. That is what I thought but the two Chinese carbon wheel manufacturer that I have asked said I can't put a 23mm on the 25mm rim... I don't see why not. 

From aero wise I would think 23mm on 25mm would be better than 23mm on 23mm.


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## Lombard (May 8, 2014)

Kerry Irons said:


> Not an issue in any way. You can put pretty wide tires on pretty narrow rims and pretty narrow tires on pretty wide rims. Your proposals are no where near "the edge" of compatibility.


^This.^


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## Lombard (May 8, 2014)

jchau said:


> Thanks. That is what I thought but the two Chinese carbon wheel manufacturer that I have asked said I can't put a 23mm on the 25mm rim... I don't see why not.


Is the 25mm rim you are talking about the INTERNAL or EXTERNAL width?


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## jchau (Jul 16, 2012)

From the attached diagram. 25mm is external with. 18mm internal.


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## Lombard (May 8, 2014)

jchau said:


> From the attached diagram. 25mm is external with. 18mm internal.


18mm internal width is well within the range that a 23mm tire can run. I don't see a problem unless there is something inherent with those particular rims. Maybe the shape of the bead seat is just a guess?


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## RoadCube (Nov 22, 2006)

I hear you; my 2007 Lemond Buenos is tight. I can run a Bontrager 25 without hitting seat stay top bridge. But a 25 Vitoria Rubino is too tall. Bicycle fits me well but I only can run narrow tires.
RC


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## JerryLook (Dec 3, 2017)

I run a similar set of wide wheels with 700/23 tires. 
I like the profile of the tires better on the wide wheels versus my old narrow wheels. It is a rounder profile versus taller. 
The tires went from just under 23mm wide on the old wheels to just over 24mm wide on the new ones. 
I can feel a difference in the bike handling. It seems to fall into corners more smoothly. 

I had similar questions about running the smaller tire size and asked the wheel builder directly. He told me I could run down to a 19mm tire safely. Not that I would want to. Lol


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## jchau (Jul 16, 2012)

JerryLook said:


> I run a similar set of wide wheels with 700/23 tires.
> I like the profile of the tires better on the wide wheels versus my old narrow wheels. It is a rounder profile versus taller.
> The tires went from just under 23mm wide on the old wheels to just over 24mm wide on the new ones.
> I can feel a difference in the bike handling. It seems to fall into corners more smoothly.
> ...


Which tire are you running? I thought 23mm tires on 23mm rims are slightly wider than 23mm.


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## JerryLook (Dec 3, 2017)

Rubena slicks. 

The old wheels were 19 or 20mm wide external. The tires were slightly less than 23mm wide. I don’t remember the exact numbers. 

The new wheels are 24mm wide external. The same tires are a tad over 24mm wide measured on those. 

I think some 23mm tires are wider and some are narrower depending on the brand. The Rubena tires would be pretty close to 23mm mounted on a 23mm rim I bet. Tires like the GP4000 (700/23) would be closer (or over) 25mm on a 25mm rim


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## Lombard (May 8, 2014)

JerryLook said:


> The old wheels were 19 or 20mm wide external. The tires were slightly less than 23mm wide. I don’t remember the exact numbers.
> 
> The new wheels are 24mm wide external. The same tires are a tad over 24mm wide measured on those.


Keep in mind that the external dimension of a rim is meaningless when it comes to the affect on your tire width. You need to find the internal width of these rims to do a fair comparison of how they affect your tire width.


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## jchau (Jul 16, 2012)

I guess no one has data on what are the safe numbers on the internal width per tire width?


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## cxwrench (Nov 9, 2004)

jchau said:


> I guess no one has data on what are the safe numbers on the internal width per tire width?


If you're still worried about running 23mm tires on 25mm external width rims, stop worrying. They'll be fine.


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## Kerry Irons (Feb 25, 2002)

jchau said:


> I guess no one has data on what are the safe numbers on the internal width per tire width?


Safety is not really the issue. I suppose if you were to try extreme combinations (50 mm tires on super-narrow rims) you might have issues, but over a VERY broad range there are no real concerns. This is why "no one has data."


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## Lombard (May 8, 2014)

jchau said:


> I guess no one has data on what are the safe numbers on the internal width per tire width?


Go to DT Swiss' website. Look up any rim or wheel. One of the attached PDF files has a chart with this info. This should set you at ease.


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## jchau (Jul 16, 2012)

Lombard said:


> Go to DT Swiss' website. Look up any rim or wheel. One of the attached PDF files has a chart with this info. This should set you at ease.


According to DT Swiss it is a no and most manufacturer will have similar charts.


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## cxwrench (Nov 9, 2004)

jchau said:


> According to DT Swiss it is a no and most manufacturer will have similar charts.
> View attachment 322182


So I guess it's some kind of miracle that we all survived putting 2" tires on the first mtb rims? And mounted cx tires on narrow road rims? I'm lucky to be alive after looking at this chart. You're definitely overthinking this to a huge degree.


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## Clipped_in (May 5, 2011)

I have about 10k miles on a set of HED Belguim+ rims (25mm) and 23mm Michelin P4 Endurance tires. The tires measure just under 26mm wide installed. Zero problems and great performance! As has been said - you're cleared for takeoff!!!


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## Lombard (May 8, 2014)

jchau said:


> According to DT Swiss it is a no and most manufacturer will have similar charts.
> View attachment 322182


Unless I am blind and seeing this chart wrong, it sure looks like your 23mm tires will work just fine on your 18mm internal width rims.

I have said it umpteen times and I will say it again, it does not matter one bit what the external withof your rims are - 23mm, 25mm, etc. Your rims are 18mm INTERNAL width. According to the chart, you can run your 23mm tires on rims up to 20mm INTERNAL width regardless of what the EXTERNAL width is.


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## malix05 (Nov 15, 2018)

the picture from HED looks very interesting.
Does someone had the original document or a link to HED web page where I can find it?
It would be very useful for my research!
Thanks for any help you can provide me!


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## jchau (Jul 16, 2012)

malix05 said:


> the picture from HED looks very interesting.
> Does someone had the original document or a link to HED web page where I can find it?
> It would be very useful for my research!
> Thanks for any help you can provide me!


Don't remember the link exactly but I think it was a white paper from HED website. Try searching their website for it.


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## kiwiguyinoz (Apr 4, 2004)

I agree with a lot of what is said above.
External rim width nly matters for brake clearance - it is the internal width that matters for tire shape and volume.
We make our standard road rims 18mm internal so that they work nicely with 23mm tires. Start going wider than that and some frames will start having clearance issues. We don't want to sell wheels to only those with new frames designed for wider rims so we settled on 18mm for now.
Since we do carbon rims - the wide external dimension means a really nice smooth transition from tire to rim. Use a 23mm tire instead and the rim will be a tiny bit wider - which is actually better for aero than the tire being wider than the rim.


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