# Are 25mm Vs. 23mm Tires faster or Slower-Your Experience?



## woodys737

I have always run 23mm tires. Lately I found a good line on Michelin Pro 4's. The 23's I like. The 25's not so much. They feel sluggish at best and after many runs with the PM compared to the 23's they are slower. I totally understand my n=1 data could be completely bogus but none-the-less I'm left with a bad taste in my mouth. I'm not really new to any of this and I'm slightly confused as many pro's are switching; many friends who race are switching. 

I'm 155 pounds and run 85-90psi on the front and 5 more on the rear. Running the same wheels. Am I wrong in thinking all things equal the 25's should be faster due to a more round contact foot print (less crr)? Or are 25's mostly about lower psi and comfort? Any insight?


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## adam_mac84

search for Zinn's articles about rolling resistance. The 25's are faster. the pro peleton is also going to them with their wider rims, for better aero and feeling 'fresher' at the end (comfort)... according to cycling news in an article during the Giro last year


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## dgeesaman

Use whichever you prefer. The fact that even the pro peloton is not unanimous in their tire width choice should serve as evidence that if there is a difference in performance, it's very small.

Personally I used both 23 and 25mm. I've switched back and forth a couple of times and honestly I don't notice a big difference.


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## Fireform

I think one thing people are missing is that rolling resistance differences between similar tires of different widths, while measurable, are minuscule. Aerodynamic drag differences, especially if the tire is significantly wider than the rim, may more than offset rolling resistance. I suspect that's why Zipp, for instance, still recommends 22-23mm tires for their firecrest rims.


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## cxwrench

Fireform said:


> I think one thing people are missing is that rolling resistance differences between similar tires of different widths, while measurable, are minuscule. Aerodynamic drag differences, especially if the tire is significantly wider than the rim, may more than offset rolling resistance. I suspect that's why Zipp, for instance, still recommends 22-23mm tires for their firecrest rims.


oddly enough, Zipp only makes 21 & 23mm tires. you don't think they'd publically recommend something they don't make, do you?


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## woodys737

It's hard to convey what I'm feeling. It's much like going from a nice Vittoria Corsa Evo CX to a Michelin Lithion or a Hutchinson Equinox or a Tufo S33. Like riding through mud type of feeling. Must just be me.


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## Dave Cutter

dgeesaman said:


> .......... Personally I used both 23 and 25mm. I've switched back and forth a couple of times and honestly I don't notice a big difference.


I am trying 23's for the first time this season. I had been what I thought was too heavy for 23's until I dropped some weight. Now I am getting to try 23's and I glad I can. I would love to say the tires make me faster. But they don't.


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## NJBiker72

Dave Cutter said:


> I am trying 23's for the first time this season. I had been what I thought was too heavy for 23's until I dropped some weight. Now I am getting to try 23's and I glad I can. I would love to say the tires make me faster. But they don't.


I felt faster when I switched to 23s from 25s and definitely feel slower when I ride 28s. But the "science" is supposedly wider is faster at the same pressure. But no one rides them at the same pressure.


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## Fireform

cxwrench said:


> oddly enough, Zipp only makes 21 & 23mm tires. you don't think they'd publically recommend something they don't make, do you?


You make a fair point. Zipp does a lot of wind tunnel testing. Why would the not offer a 25mm tire if it would be a more aero match to their rims? I would think the ads would write themselves. 

I still think the aerodynamic drag of a wider tire, especially one that's much wider than the rim, will likely more than offset the difference in rolling resistance.


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## r1lee

Fireform said:


> I think one thing people are missing is that rolling resistance differences between similar tires of different widths, while measurable, are minuscule. Aerodynamic drag differences, especially if the tire is significantly wider than the rim, may more than offset rolling resistance. I suspect that's why Zipp, for instance, still recommends 22-23mm tires for their firecrest rims.





cxwrench said:


> oddly enough, Zipp only makes 21 & 23mm tires. you don't think they'd publically recommend something they don't make, do you?


Enve, Reynolds also recommend 23mm with HED recommending 22-23mm.


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## Dave Cutter

NJBiker72 said:


> I felt faster when I switched to 23s from 25s and definitely feel slower when I ride 28s. But the "science" is supposedly wider is faster at the same pressure. But no one rides them at the same pressure.


I am six foot tall.... so I am not a light weight but 177 pounds isn't fat ether. I ride at the recommended PSI for my old 25 and new 23 which for both is 110psi. 

My new 23's feel great and are tacky as glue.... but they did cost twice as much as well. So far... I am very happy with the trial.


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## Jay Strongbow

cxwrench said:


> oddly enough, Zipp only makes 21 & 23mm tires. you don't think they'd publically recommend something they don't make, do you?


you don't think they'd make something they don't recommend, do you? In other words it depends how you look at it. I doubt it would be a big deal for Zipp to call Vittoria (or whoever is making their tires now) and just order some 25s made in the Zipp name so I wouldn't read much into them not making 25s and not recommending them.

Anyway OP, my unscientific opinion on the slow feel is that it is just that, feel only, and you are not actually going any slower. My explaination for that (again, unscientific) is the the bigger tire in the front does slow down your responsiveness in handling a little and that give the false sensation that the bike is going slower with equal effort as compared to a 23 that's a bit more twitchy/responsive.

I'm also 155ish like youself and what I've found to work really well is 25 (acutally 24, Vit Paves) in the rear and 23 in the front. It makes the seat end of the bike feel smoother without any change in handling up front. 
Try using 25 in just the back. Or keep using 23s if that's what you like.


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## Fireform

r1lee said:


> Enve, Reynolds also recommend 23mm with HED recommending 22-23mm.


What tires do enve and Reynolds make? Lol.


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## cmg

not a fan of 25mm tire width. I too think they're sluggish. i always recommend 25mm gatorskins with puncture resistant inner tube to my faster friends.


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## looigi

FWIW: putting tires on wider rims make them behave more like wider tires in some ways. 23mm wide tires on my 19 mm rims measure 25mm wide on 23mm HED C2 rims. You can run 25mm pressures in 23mm tires and the more vertical sidewall improves handling when cornering, IMO.


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## Dave Cutter

Jay Strongbow said:


> ......
> ... my unscientific opinion on the slow feel is that it is just that, feel only, and you are not actually going any slower. My explaination for that (again, unscientific) is the bigger tire in the front does slow down your responsiveness in handling a little and that give the false sensation that the bike is going slower with equal effort as compared to a 23 that's a bit more twitchy/responsive.


That is a good description of what I am feeling with my new 23's. Although... my bicycle computer hasn't shown any speed increases...yet. It is mid-winter here and the cold wind does minimize my effort a little. But I do like the "feel" of the tires... they are responsive. 

I am just a recreational rider... a couple thousand miles a year. I am an old retired guy... and racing isn't in my future. If I was going touring I am sure I'd want some fat cushy rubber beneath me. But with 20-25 mile urban and bike path rides being more like my daily fare... I like the opportunity for a little more excitement.


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## woodys737

When I get healthy enough to ride again I'm going to re-examine the pressures I'm using. I have a PM. I have the same tire in a 23 and 25. Lots of zero wind morning around here. Should be able to get some good ol' fashioned subjective data with a flat section run and a roll out test with various pressures. Maybe I was too quick to make a call but, for sure using 100psi front/105psi rear for the 23's and 90f/95r for the 25's the 23's were (via subjective runs with PM) faster.


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## Dunbar

woodys737 said:


> Maybe I was too quick to make a call but, for sure using 100psi front/105psi rear for the 23's and 90f/95r for the 25's the 23's were (via subjective runs with PM) faster.


You may just be confusing a more _compliant_ (25mm) tire at lower pressure as being more sluggish than a harder 23mm tire. I've lost count of the number of times I've seen somebody post something to the effect of "if I use any less than maximum inflation pressure the tire feels sluggish." I can only assume their bodies are conditioned to associate rock hard tires with being faster.


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## dcgriz

I don't remember who's done it but a test on Crr showed a 0.3 watt difference between a 23 and a 25mm tire. So other than the perception that a higher pressure tire rolls faster because of its bouncing, I cant imagine how such a small difference could even be detectable by the rider.


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## brianmcg

Dunbar said:


> You may just be confusing a more _compliant_ (25mm) tire at lower pressure as being more sluggish than a harder 23mm tire. I've lost count of the number of times I've seen somebody post something to the effect of "if I use any less than maximum inflation pressure the tire feels sluggish." I can only assume their bodies are conditioned to associate rock hard tires with being faster.


I agree. There is a phenomenon, I don't know the name of it but I believe its real.

I can only explain it like this:
I had a 10 year old Mazda GLC in high school (think chevete). It had a 70 horsepower engine. If I floored it going down this particular hill on the highway I could get it up to 80. The car would be shaking so bad I could hear Scotty from Star Trek screaming "She's breaking apart!!!" It really FELT fast.

10 years later I drove my brothers Corvette. I could set the cruise control at 85mph and almost fall asleep its so smooth.

Which one felt faster? If I didn't have a speedo I would have said the Mazda was going easily 100mph. But it wasn't.

Well that's my 2cents.


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## mustang1

I feel faster on 23 than 25 on the same bike.
The 23 on my carbon bike feels faster than 25 on my alu bike.
Therefore 23 is faster than 25.

Ps: rolling resistance is better on 25s? Pah. No it isn't. Whenever we see these tests that shows 25s deform less than 23s, they always measure with the same psi. But who wants to put the same psi in a 25mm as a 23mm?


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## woodys737

Dunbar said:


> You may just be confusing a more _compliant_ (25mm) tire at lower pressure as being more sluggish than a harder 23mm tire. I've lost count of the number of times I've seen somebody post something to the effect of "if I use any less than maximum inflation pressure the tire feels sluggish." I can only assume their bodies are conditioned to associate rock hard tires with being faster.





mustang1 said:


> I feel faster on 23 than 25 on the same bike.
> The 23 on my carbon bike feels faster than 25 on my alu bike.
> Therefore 23 is faster than 25.
> 
> Ps: rolling resistance is better on 25s? Pah. No it isn't. Whenever we see these tests that shows 25s deform less than 23s, they always measure with the same psi. But who wants to put the same psi in a 25mm as a 23mm?


As luck would have it just a few hours ago I saw the 23 v25 thread in the endurance forum. My search skillz really suck. :mad2: Sorry for dredging this up for the nth freaking time.

What I've missed the entire time is precisely what you all point out and I'll definitely re visit pressure when I get back on the bike. Specifically I'll run higher pressure on the 25's similar to the 23's and see if I can verify anything with the PM. Thanks again for pointing out the obvious. A bit embarrassed I missed it. Just took what several charts recommended to inflate to and never looked back...


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## dnice

Implications of Rim Width - Slowtwitch.com

does anyone else get the same message from the above article that i do: we are all measuring the wrong thing, and if we were, we'd all be riding on 25's, at a minimum, however 23's are adequate. also, don't worry about it so much, choose a great tire and enjoy the ride.


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## EMMANUEL151

No 23 is wide eneugh , but continental mesures are really small a 25 conti is a 23 michelin.


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## Salsa_Lover

The argument about the 25mm tyres being "faster" than the 23mm is a recurrent one in RBR.

It is a fallacy, because the studies that had been made proove only that a 25mm tyre inflated at the same preassure as a 23mm tyre, would have less rolling resistance.

But the fact is the only reason to use a 25mm tyre or bigger is to have the posibility to run it at a lower preassure, and that for comfort reasons, not for performance ( aka speed ) reasons.

However this argument is commonly used by people who try to "shoehorn" and rationalize their choice of fat tyres on a "racing bike".

a 23mm tyre is fat enough for a road bike, but if you want more "cushy" you can ride a 25 or 28, those will be more comfortable, but off course will feel "sluggish" for riders used to thinner tyres, and no, them fat tyres, won't be "faster" in any way.


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## [email protected]

woodys737 said:


> I have always run 23mm tires. Lately I found a good line on Michelin Pro 4's. The 23's I like. The 25's not so much. They feel sluggish at best and after many runs with the PM compared to the 23's they are slower. I totally understand my n=1 data could be completely bogus but none-the-less I'm left with a bad taste in my mouth. I'm not really new to any of this and I'm slightly confused as many pro's are switching; many friends who race are switching.
> 
> I'm 155 pounds and run 85-90psi on the front and 5 more on the rear. Running the same wheels. Am I wrong in thinking all things equal the 25's should be faster due to a more round contact foot print (less crr)? Or are 25's mostly about lower psi and comfort? Any insight?


I think your feelings are mostly correct with regard to sluggish feeling. The science on this topic seems pretty clear. Wider tires do roll faster, however this is usually offset by increased weight. If they feel sluggish to you is this perhaps because the extra weight is effecting your accelerations?


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## Scott AFD

I can't see any real difference between 23 and 25mm. But I like 23mm for my bike.


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## woodys737

[email protected] said:


> I think your feelings are mostly correct with regard to sluggish feeling. The science on this topic seems pretty clear. Wider tires do roll faster, however this is usually offset by increased weight. If they feel sluggish to you is this perhaps because the extra weight is effecting your accelerations?


I'm pretty sure it's a pressure issue I was seeing. I was using what I thought was optimal but ended up being 10-15psi less. Once I have some time I'll use the same pressure in both the 23 and 25's and see what I see. Both sets are the Michelin Pro4...


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## danl1

This is a fun, confusing topic, mostly based on the errant American assumption that if some is good, more is better. Tires got too narrow that way, now they are at risk of going too wide in the same way.

Wider rims with the same tires create the effect of a wider rim for contact patch and improve aerodynamics. Good stuff. That benefit does not translate into wider tires on narrow rims, because the aero benefit is gone and you add tire weight. bigger on both tires and rims moves towards 'too much of a good thing.'

Unless you happen not to be built like a professional racer, which very few of us really are. In that case, perhaps it does make more sense.

And the crr measurements noted above are accurate, but inadequate. They are measured on smooth rollers most of the time, but even if they use rough rollers, they don't usually account for suspension losses. And that can be a significant factor. The only work I've seen done on the issue is from Jan Heine: 

Science and Bicycles 1: Tires and Pressure | Off The Beaten Path
This reference doesn't address tire width directly, but some related work does. 

One other thing people often forget: a wider tire at the same pressure as a narrow one will also offer less suspension, and be effectively 'harder,' because they will create significantly higher tension in the casing. They'll also risk splitting the rims or blowing themselves apart, which is why they have lower maximum pressures.

All to say, there is no single right answer between "is skinny or wide better/faster/more comfortable." More factors at play.


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## nhluhr

Salsa_Lover said:


> The argument about the 25mm tyres being "faster" than the 23mm is a recurrent one in RBR.
> 
> It is a fallacy, because the studies that had been made proove only that a 25mm tyre inflated at the same preassure as a 23mm tyre, would have less rolling resistance.
> 
> But the fact is the only reason to use a 25mm tyre or bigger is to have the posibility to run it at a lower preassure, and that for comfort reasons, not for performance ( aka speed ) reasons.
> 
> However this argument is commonly used by people who try to "shoehorn" and rationalize their choice of fat tyres on a "racing bike".
> 
> a 23mm tyre is fat enough for a road bike, but if you want more "cushy" you can ride a 25 or 28, those will be more comfortable, but off course will feel "sluggish" for riders used to thinner tyres, and no, them fat tyres, won't be "faster" in any way.


Agree 100%... additionally, a 25 inflated to the same pressure as a 23 will be noticeably less comfortable, since the effective spring rate will be higher with the wider tire. Further, the wider tire will have less directional stability at the same pressure since its contact patch will be shorter and wider for a given load (this is called pneumatic trail).

When you run the wider tire at the lower tire pressure, you lose any rolling resistance benefit AND you gain additional aero drag. If you're running high-zoot aero wheels which were optimized for 23 or narrower tires, the aero characteristics of your rims are going to be partly ruined by the wide tire since it will create separations where there are not supposed to be any.

Make no mistake - running wider tires is purely a comfort choice or load issue. If you need additional comfort or additional load capacity (fat ass or really rough roads), go for the wider tire. Just understand, it will cost you some small amount of speed.

Personally, I feel the trade-off is often worth it. For my seattle winter commutes, running a wide tire at lower pressure makes sense because the lower pressure wide tire better resists punctures, and is more forgiving in traction-limited situations.


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## mustang1

Not to drag those solar Honda record breaking cars into the mix, but they use pretty skinny tires. I guess they figured out optimum rolling resistance vs drag vs psi vs bunchOfOtherStuff.

When i switched to 25mm tires @ 100psi instead of 23mm " 120psi, i noticed more comfort, less punctures, the feel of lower speed. I have no science on the speed, but punctures are def lower, comfort def higher. I only roll with 25mm now, and have done for a few years.


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## ZoSoSwiM

I went from 25's most of the spring last year to 23's later in the year then back to 25's toward the end of summer. 

23's feel harsher than 25's almost all of the time. The sense of speed is higher on 23's because of the harshness IMO.. Speedo says it's the same though. 

25's feel more floaty and less harsh and I feel better during the ride. Speed doesn't suffer. Corning feels more connected as well.

So in the end why ride a harsh feeling setup unless for some reason you enjoy it? I prefer a smooth ride so I'm a fan of 25's! These are just my opinions.. ymmv.


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## woodys737

Man I must be out to lunch because at the lower psi the 25's didn't feel more comfortable at all, punctures went to an all time high (new tires) and speed most definitely went down. I use the tires for crits and road races so comfort isn't really the issue.


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## ChallengeTires

*Wide tubulars and clinchers from Challenge*



adam_mac84 said:


> search for Zinn's articles about rolling resistance. The 25's are faster. the pro peleton is also going to them with their wider rims, for better aero and feeling 'fresher' at the end (comfort)... according to cycling news in an article during the Giro last year



True, Zinn lays out the issue very well over two pieces, and I would agree with the performance car analogy, but it is a matter of feel. Some people love it, but don't feel like you have to stick to it if you don't like it.

If you are looking for wide tires, check out Challenge's Strada 25, available in tubular and open tubular/clincher. 25mm 300TPI SuperPoly casing. It's a great ride.


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## mustang1

ChallengeTires said:


> True, *Zinn lays out the issue very well over two pieces, and I would agree with the performance car analogy,* but it is a matter of feel. Some people love it, but don't feel like you have to stick to it if you don't like it.
> 
> If you are looking for wide tires, check out Challenge's Strada 25, available in tubular and open tubular/clincher. 25mm 300TPI SuperPoly casing. It's a great ride.


I just started reading Zinn's artilce, but once again he started off with both 23 and 25mm tires having the same pressure and thus the 25 deforms less at the contact patch. If he then continued this with 32mm tires (ie 32mm tires with same air pressure), it wont be right, no one pumps 32mm to same psi as 23 regardless of whether they will pop or not.

So starting with the premise that both 23 and 25 have the same psi is incorrect and then explaining the theory based on that is also incorrect.

Performance cars have wider tires for traction. Laying down lots of power for acceleration, traction for braking, and traction for going round corner. On the other hand if we look at cars which require very low rolling resistance, it's those economical cars, maybe Prius or solar power record breaking cars, you see how slim those tires are?


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## Dunbar

mustang1 said:


> So starting with the premise that both 23 and 25 have the same psi is incorrect and then explaining the theory based on that is also incorrect.


According to the following article this is a straw man argument. There is no qualification that 25mm tires are only faster than 23mm tires at the same pressure.

Bicycle Quarterly: Performance of Tires | Off The Beaten Path


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## morgan1819

The funny part of all of this, is that the new Service Course 25's are essentially the same width as the old 23's. I noticed the new ones don't say made in France on the tire (although the box indicates France). Hmm??

The old Michelin Pro Race 2/3 25's were monsters though... I had some measure out at 28mm. 

I much prefer the new Michelin Pro Race 4 in 25mm over 23mm. My lap times are exactly the same, but the ride is noticeably nicer. This isn't theory, or regurgitating something I read somewhere. This was a summer's worth of riding.

I weigh 165 lbs, and run 105 psi in the rear tire, and 85 psi front. Michelin Aircomp tubes. I ride patchy, chip seal roads. 

I would imagine that a lighter rider on perfectly smooth roads would indeed prefer a 23 ... unfortunately that's not the case with me.


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## dirttorpedo

I'm no expert on the topic, but I was under the impression that contact area and tire width were only one part of the efficiency equation. Doesn't rubber compound, tire weight and structure play a large role as well?


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## mustang1

Dunbar said:


> According to the following article this is a straw man argument. There is no qualification that 25mm tires are only faster than 23mm tires at the same pressure.
> 
> Bicycle Quarterly: Performance of Tires | Off The Beaten Path


Good link. I will read that soon.
The point I was making is not that 23 is faster than 25, but that people who claim 25 rolls faster than 23 always base that on both tires having the same pressure. You can also go further: why stop at 25? Why not compare 23mm at 120psi (for example) and 50mm at 120psi (wow). Alternatively, a 50mm at 30psi and a 23mm also at 30psi. You can see in theory we can talk about same psi, but in practice that is not such a good comparison.


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## dracula

EMMANUEL151 said:


> No 23 is wide eneugh , but continental mesures are really small a 25 conti is a 23 michelin.


You should measure the bead to bead. My Continental GP 700x24 measures 65mm from bead to bead. A Michelin Endurance Pro4 measures 60mm from bead to bead (the older Michelins 700x23c measured 64mm from bead to bead). 

To the OP: a labelled 25mm Michelin is a 28mm tyre really. Measure the bead to bead and you gonna see it will be 72mm. I haven't seen a newer 25mm Michelin but think the idiots decreased the bead to bead measure from 64mm (which was quite a good compromise) to 60mm for the newer Pro4 series but left the 72mm bead to bead for the 25mm intact which was always a 28mm tyre. I really wished the new Pro4 in 25mm would be 65mm from bead to bead.


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## morgan1819

dracula said:


> You should measure the bead to bead. My Continental GP 700x24 measures 65mm from bead to bead. A Michelin Endurance Pro4 measures 60mm from bead to bead (the older Michelins 700x23c measured 64mm from bead to bead).
> 
> To the OP: a labelled 25mm Michelin is a 28mm tyre really. Measure the bead to bead and you gonna see it will be 72mm. I haven't seen a newer 25mm Michelin but think the idiots decreased the bead to bead measure from 64mm (which was quite a good compromise) to 60mm for the newer Pro4 series but left the 72mm bead to bead for the 25mm intact which was always a 28mm tyre. I really wished the new Pro4 in 25mm would be 65mm from bead to bead.


Drac,

I received the Pro 4 Service Course 25mm as a gift, and didn't measure them before installing, but they are definitely not as large as my old Pro Race 25mm. 

The old Pro Race 25mm measured out at 27+mm in width, the newest versions are right at 25mm.

Also, you are correct on the Pro 4 Endurance (formerly known as Krylion) being small as well. My last set of 23mm Krylion's were made in Thailand rather then France, and measured 22mm ... definitely smaller than the old pre-Thailand versions. They were little harsher riding as well, in my opinion.


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## terbennett

dgeesaman said:


> Use whichever you prefer. The fact that even the pro peloton is not unanimous in their tire width choice should serve as evidence that if there is a difference in performance, it's very small.
> 
> Personally I used both 23 and 25mm. I've switched back and forth a couple of times and honestly I don't notice a big difference.


/
+1... I have to agree with this. If I ever felt a difference, it wasn't that big of a difference. This topic will be debated continuously because there is no definitive answer. Individual experiences determine which one is best. Plus unless you race, your wasting your time being concerned with such things. Then again, I do race and can hardly tell the difference in ride quality. Speed? I can't tell any difference at all.


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## Barteos

It's a slightly old thread but as a tyre geek I couldn't resist.

Like it or not, wider tyres have lower rolling resistance not just at the same but at their optimal pressure (e.g. using 15% tyre drop method).

As Bicycle Quarterly demonstrates in their tests (largely paid content - so most of people have never seen it), on perfectly smooth surfaces the differences are negligible but on typical far from perfect roads the ability of running several PSI less without increasing the risk of pinch flats makes you roll measurably faster. 

How wide is wide?

Please have a look at this thread (mid page)
*How do we build ourselves a fast road bike... that isn't a road bike? - Page 3
* in which I'm describing my experience of regularly riding 18-19mph (50-150min. long rides) on 2.10" wide "shaven" Racing Ralph mountain bike tyres at 20,30PSI, tubeless.
View attachment 280940
View attachment 280941

I would never suggest that everyone should be riding such wide tyres but the it demonstrates how far you can push tyre width without compromising your speed by increased weight or air resistance.

The funniest thing in all tyre discussions is that there's actually NO research suggesting that 23mm-28mm tyres are "the best compromise" for vast majority of recreational, non-competing road cyclists... 
They are just standards used by pros and that's what marketers will always be trying to sell you.

This strategy is certainly very effective

P.S. You can't "feel" rolling resistance. You have to measure it. 23mm at 120PSI will always *feel* faster than 28mm at 80PSI.


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## Maximus_XXIV

Aren't we talking about mere seconds over miles of riding? This is something that any number of factors can impact so it would 1) be hard to feel and 2) hard to know what caused the change in speed.

As others mentioned, you also need to measure the tires with calipers and not just trust the sidewall. There is quite a bit of variation out there.


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## SystemShock

Interesting– apparently most of the 2013 Giro field is on 25mm tires now.

*http://forums.roadbikereview.com/ge...on/2013-giro-90%-field-25mm-tires-305815.html*


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## Pete_G

I've always felt part of the "sluggish" feeling when you switch from 23mm to 25mm was because the effective gear ratio had been ever so slightly increased. In other words, you might FEEL slightly slower since the gearing is slightly taller, but other then that, the changes were minimal in terms of actual speed.

And of course the opposite when you go back.

Ever put slightly bigger diameter tires on a car or truck? It instantly feels like it lost horsepower. Even new tires of the same size on a car sometimes feel sluggish as they gained back the diameter they lost as they were used up. 

I don't know the science of it or how minimal the effect is but it has to be in there as part of the "change" that is perceived. The same gear as before should feel slightly taller.


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## dcgriz

Whenever I can not keep up with the A or AA group, I always blame my 25 or 28mm tires.


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## nOOky

Couple of general comments. Tire widths mounted on rims differ greatly. Not all 23mm tires measure 23mm mounted, not all 25mm tires are 25mm, you get the idea. Differing rim widths change that equation once again. The air pressure you run can influence the ride more than the tire brand, try experimenting with that more.
Almost universally, people that change from one brand of tire to another feel like it's a positive change, never mind that they are removing worn out tires and installing new ones. People generally tend to run the same air pressure every ride and with different brands of tires, which can make a great tire feel sluggish and vice versa.
Despite what the pros are using, the average speed on the grand tours isn't much faster than when they were using the "old tech" 23mm tires or even carbon wheels. It's kind of hard to quantify as the routes vary each year, but I suspect there isn't a 3mph difference at the end of the race 

This is only my opinion, but I doubt that most of us that went to 25mm tires and wider rims are any faster then before, but hopefully the ride is a tad more tolerable.


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## Rickard Laufer

I read of increased comfort with wider tires and decided to have a go at this.
So, i changed from Continental Force (24) and Attack (22) to Schwalbe Ultremo ZX 25mm's front and rear. Went with lower psi for the fatsos. Expected a decrease in vibrations and a more smoothed out ride, was i wrong!
I noticed a decrease in speed, not much but i can swear they are slower.
The comfort i was expecting, i can't say was static. At times it felt a bit smoother, at times it was vice versa. I was really noticing a more prone effect to vibrations, especially in the seatpost/ saddle and ass. I ran 85 psi in the rear and 75 psi in the front. My Contis i ran 85-90 psi in the front and 95-100 psi rear.


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## SystemShock

Rickard Laufer said:


> I read of increased comfort with wider tires and decided to have a go at this.
> So, i changed from Continental Force (24) and Attack (22) to Schwalbe Ultremo ZX 25mm's front and rear. Went with lower psi for the fatsos. Expected a decrease in vibrations and a more smoothed out ride, was i wrong!
> I noticed a decrease in speed, not much but i can swear they are slower.
> The comfort i was expecting, i can't say was static. At times it felt a bit smoother, at times it was vice versa. I was really noticing a more prone effect to vibrations, especially in the seatpost/ saddle and ass. I ran 85 psi in the rear and 75 psi in the front. My Contis i ran 85-90 psi in the front and 95-100 psi rear.


Some brands/lines run small. Your Ultremo ZXs may not really be '25s':

_ I had a similar experience with Schwalbe Ultremo ZX clinchers in a 25mm size which mounted onto Eurus 2 way fit rims ( a 20.5mm wide rim) at only 23.8mm, which is only 95.2% of specified width...
_
BNA - Australian Cycling Forums ? View topic - 700 x 28... I don't think so


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## Rickard Laufer

SystemShock said:


> Some brands/lines run small. Your Ultremo ZXs may not really be '25s':
> 
> _ I had a similar experience with Schwalbe Ultremo ZX clinchers in a 25mm size which mounted onto Eurus 2 way fit rims ( a 20.5mm wide rim) at only 23.8mm, which is only 95.2% of specified width...
> _
> BNA - Australian Cycling Forums ? View topic - 700 x 28... I don't think so


Well, i don't know external and internal rim width of Fulcrum Red Wind XLR 50.
But to the eye, the ZX looks larger than the Contis i had. My gripe is that i prefer the Contis which sadly were damaged running on new laid asphalt. I tried these due to what i've read of wider tires. Perhaps i'll go back to Contis or try something different next time. The Force and Attack had just that, they were faster. Looking at speedo down hill i achieved higher speed with the Contis and they felt more prone to accelerate faster and to.


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## SystemShock

Rickard Laufer said:


> Well, i don't know external and internal rim width of Fulcrum Red Wind XLR 50.


They're narrow rims, 20.5mm wide, just like the Eurus rims from the example I quoted.

wiggle.com | Fulcrum Red Wind 50 XLR (USB) Clincher Wheelset | Road Race Wheels

Which, if the other gent I quoted is credible, would seem to mean your Ultremos likely measure somewhere around 23.8mm, like his (things like tire stretch notwithstanding... though, since your tires are new, that might mean yours are even narrower).

On top of that, some tires just don't have a really great 'feel'... maybe they run a puncture resistance belt that's a bit stiff, the casing isn't all that supple, etc. etc.

Don't know if the Ultremos fit into that category, but given their true width, for comfort I'm pretty sure you can do better.


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## jaminM3

A super fast descender around here recommended I run 25mm if I wanted to corner faster in crits and canyons and the rolling resistance is the same or close enough. I think I will give a pair of 25mm a try next year in the crit series.


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## captain stubbing

On a super smooth velodrome, a 23 at max psi will be faster;
On the roughest road a 25 at lower psi will be faster;
In the real world, u will be somewhere in between, on occasions a 23 may be marginally faster and on others the 25 will be....however the difference is negligible.
For me, the most important thing is not too have much psi on a given ride, as the result is getting fatigued through the increased vibration/shock.
On short rides, i’m not bothered....on long ones, I’ll reduce my usual psi by about 5 – 10psi for added comfort so that I’ll be fresher to push the whole way.
Btw, i have bikes with 23s, 24s and 25s in various brands.....and they are not all the same, the Pro4 def run wider than the conti’s for example.


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## terzo rene

dcgriz said:


> I don't remember who's done it but a test on Crr showed a 0.3 watt difference between a 23 and a 25mm tire. So other than the perception that a higher pressure tire rolls faster because of its bouncing, I cant imagine how such a small difference could even be detectable by the rider.


 Speak for yourself - that 0.3 watts is easy to detect when it's 10% of your max!


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## nito

captain stubbing said:


> On a super smooth velodrome, a 23 at max psi will be faster;
> On the roughest road a 25 at lower psi will be faster;
> In the real world, u will be somewhere in between, on occasions a 23 may be marginally faster and on others the 25 will be....however the difference is negligible.
> For me, the most important thing is not too have much psi on a given ride, as the result is getting fatigued through the increased vibration/shock.
> On short rides, i’m not bothered....on long ones, I’ll reduce my usual psi by about 5 – 10psi for added comfort so that I’ll be fresher to push the whole way.
> Btw, i have bikes with 23s, 24s and 25s in various brands.....and they are not all the same, the Pro4 def run wider than the conti’s for example.


This is true. But you also need to add in Climbing (& Descent) will be faster on the 23. Due to rotating mass, more to accelerate when climbing and more to decelerate when descending. But you will be able to carry more speed through the corner with the 25.


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## STBW

My Fuji Gran Fondo 1.3 came stock with 25s. I rode them for a bit in the spring and then switched over to 23s. I was actually riding slower with a much less comfortable ride. A buddy of mine showed me a couple of studies about the pros moving towards 25s as well as the 25s having less rolling resistance. I moved back to the 25s and saw my speed go back up again. I recently changed out my wheels to Zipps 404s and kept the 25s on there and have picked up even more speed. 

Nothing scientific about my comments other than real life results. For me, 25s and more comfortable and faster.


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