# Tire width for 23mm Rim?



## sheepherder (Mar 11, 2012)

I know of the advantages of 25mm vs 23mm tires on a narrower rim width but are those advantages still true with a 23mm rim? 

Doesn't the 23mm rim allow a 23mm tire to run lower pressure which gives all the benefits that a 25mm tire gave on a narrower rim?

I'm just trying to decide what size GP4000s to buy. Building my first 23mm rim, H Plus Son Archetype.


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## bikerjulio (Jan 19, 2010)

I thnk the answer depends on your weight and the kind of surfaces you ride on. I'm 190# and ride on poor surfaces. Therefore I have 25mm tires on my Archetypes.

Conti's run quite small BTW.


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## NealH (May 2, 2004)

I've been through numerous Conti 4000 in 25 and, have never measured one under 26mm. Most are right at 26.5mm. So I'd say they run large, generally speaking. 

Its possible a 25 tire, at a given pressure will provide a very slightly larger surface contact area but I doubt this will be anything you can tell by eye at typical road pressures, or feel from a performance perspective - though mathematically it should be better. I'm not an expert however, so take this comment will the usual gain of salt.


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## bikerjulio (Jan 19, 2010)

NealH said:


> I've been through numerous Conti 4000 in 25 and, have never measured one under 26mm. Most are right at 26.5mm. So I'd say they run large, generally speaking.


Well we must be using different calipers.

Conti's are well known for running smaller than Michelin. I have 25mm Conti's on my Supersix because 25mm PR4's won't fit. This is on regular 19mm rims.



I measured them at 25.3mm. So I was wrong in saying they run small, but for sure smaller than Michelin.


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## kbwh (May 28, 2010)

A 23mm wide rim is normally 17c, compared to a 20-21mm rim that's normally 15c.
Schwalbe has a safety table recommending that the smallest tire you should run on a 15c rim is 23mm and on a 17c 25mm
25mm on 17c _feels_ better than 25mm on 15c. In my experience, of course.


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## bikerjulio (Jan 19, 2010)

kbwh said:


> A 23mm wide rim is normally 17c, compared to a 20-21mm rim that's normally 15c.
> Schwalbe has a safety table recommending that the smallest tire you should run on a 15c rim is 23mm and on a 17c 25mm
> 25mm on 17c _feels_ better than 25mm on 15c. In my experience, of course.


I looked up that table. It's here:

Tire Dimensions | Schwalbe North America

I'm not sure how to correlate rim width to a size like "15c". Is there another table for this somewhere?

Is an Open Pro 15C for instance?

And an Archetype 17c?

Sheldon Brown's site implies that it just means the width in mm , dimension "B" on the Schwalbe chart. Is that the case?

I'm measuring Open Pros at 14.6mm

Ksyriums at 13.4mm

and some older Shimano at 15.3mm.

If so, I've been breaking the rules running 40mm tires on Open Pros on my cross bike. Had no problems at all.


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## bikerjulio (Jan 19, 2010)

I think I answered my own question. It's something of a puzzle though that there is a "standard" for rim widths, yet manufacturers seem to ignore it.



> Note that there is a distinct cutoff that we should all be concerned with – between 15c and 17c rims. As mentioned, 15c tends to be on the wide-end of old traditional road rims. For example, the ubiquitous Mavic Open Pro is a 15c rim. According to the rules, the narrowest tire you should use with this is a 23mm. You will notice that many of the newer wide rim manufacturers fail to mention the ETRTO size; they only tell you the outside-to-outside measurement of the rim. I can tell you with a high level of certainty that any 23mm wide rim is at least 17c ETRTO. Most of these rim manufacturers recommend a minimum of a 23mm tire… but that technically doesn’t fit the chart…>insert screeching halt<
> 
> Huh?! Are you at a risk of system failure, and perhaps a crash? The late bicycle genius, Sheldon Brown, suggested that the ETRTO chart is on the conservative side in its prescriptions. It is common knowledge in the mountain bike world that you can get away with a much wider tire than recommended. We also know that folks have used 18-20mm tires for years on many standard rims, including the technically-too-wide 15c standard. What does this all really mean?
> 
> The real take-home is that we should all educate ourselves on the topic, and understand that if we choose to go outside of the standards, it is at-your-own risk. As well, we should continue to push manufacturers for full-disclosure of their rim ETRTO sizes. Perhaps they will tell you if you call them up, but none currently publish this information of their new wide clincher rims. While I wouldn’t recommend using anything less than a 23mm tire on a rim that is ETRTO 17c (or 23mm outside-to-outside), it appears that many people are using this combination today without issue.


found here: Implications of Rim Width - Slowtwitch.com


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## kbwh (May 28, 2010)

Fine digging, bj. That's my source too, but I had forgotten. Refreshments are always good. Thanks. 
I 'll have to spread some reputation before etc.

Are you happy with your Archetypes? Could you tell me about the build, or maybe link to it? Seriously considering them for a custom build on DT240. 

---

I made myself a list of rims and widths which goes like this:

Mavic Cosmic (all of them): 13c
Mavic Ksyrium, Open Pro, all Campagnolo and Fulcrum: 15c
Zipp 101: 16c
Hed Belgium, Ardennes, Jet 5, Zipp Firecrest, Vision Metron, H Plus Son Archetype: 17c
Hed Belgium/Ardennes +: 19c

The last one must be for your 27mm Vittoria Pavé or CX tires I think.


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## Z'mer (Oct 28, 2013)

bikerjulio said:


> Well we must be using different calipers.
> 
> Conti's are well known for running smaller than Michelin. I have 25mm Conti's on my Supersix because 25mm PR4's won't fit. This is on regular 19mm rims.
> 
> I measured them at 25.3mm. So I was wrong in saying they run small, but for sure smaller than Michelin.


The Pro 4S run normal size in 23mm, but the 25mm are actually close to 28mm. It's been documented by 2 different published tests. So it's just the 25mm version of the Pro 4S that's the oddball. Weird, I know...
So if you have clearance issues at 28mm, and are scared by GP 4000S sidewall blowout issues, the 25mm Rubino Pro III starts to look pretty good as an training tire option, especially the slick version.


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## bikerjulio (Jan 19, 2010)

kbwh said:


> Fine digging, bj. That's my source too, but I had forgotten. Refreshments are always good. Thanks.
> I 'll have to spread some reputation before etc.
> 
> Are you happy with your Archetypes? Could you tell me about the build, or maybe link to it? Seriously considering them for a custom build on DT240.
> ...


My Ksyriums are only just over 13mm inside, which would make them closer to 13c.

I built up my Archetypes buying everything from Bikehubstore. It's my second wheel build from them (first was Pacentis). Other than the rims the builds were the same with their light hubs and Lasers. Both 20/28. With the Archetypes I daringly used alloy nipples for the first time.

Both The Pacenti and Archetype builds went fine. I have several months on the former and they have stayed absolutely true. They are a little hard to mount tires on, but that's been done to death.

Since we have been in a deep, snowy, icy freeze here for more than a month now I have zero KM on the Archetypes. Tires went on easily. But now they just sit there looking at me.

I have 25mm Michelins on them with my latest acquisition - a 2010 LOOK 585 frameset, the last production year of the Look 585.


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## Zen Cyclery (Mar 10, 2009)

I find that I still prefer to run 25cs on my SL23s. I can run in the low 90s for PSI where as I feel that going below 100 psi on my 23cs is a bit too low.


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## bikerjulio (Jan 19, 2010)

Zen Cyclery said:


> I find that I still prefer to run 25cs on my SL23s. I can run in the low 90s for PSI where as I feel that going below 100 psi on my 23cs is a bit too low.


Right. I was experimenting with lower pressures last year mainly because of the poor surfaces here. So, I'm 190#, have 25mm tires on my Pacentis, and no problems at all running 75psi front and 90psi rear.


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## kbwh (May 28, 2010)

Those H Plus Sons look really sweet. I wonder if I can get away with 20/24 radial/2x with CX-rays for my 72 kg or if I should go for 28 spokes rear. Depends on the builder, or? They will see gravel.


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## bikerjulio (Jan 19, 2010)

kbwh said:


> Those H Plus Sons look really sweet. I wonder if I can get away with 20/24 radial/2x with CX-rays for my 72 kg or if I should go for 28 spokes rear. Depends on the builder, or? They will see gravel.


The rims are stout enough that IMO a 20/24 build would be fine at your weight. Even at mine I run Neutrons which have 24 spoke rears with no issues at all. I've also run Zipps with 24 spoke rears.

Based on the usual advise here I'd not be surprised to see builders being a little more conservative though.


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## kbwh (May 28, 2010)

I just found this:
2013 Rim Roundup - Fair Wheel Bikes
and it's made me think of being lazy and just get a pair of DT Swiss RR 21 Dicut...


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