# Continental GP4000S 25mm. Do they run large?



## chudak (Jul 28, 2012)

Bought a set of these a few months ago and installed them on my Felt Z4 this weekend. I've been running the stock Vittoria Zaffiro Pro Slick in front and a 25mm Gator Skin in back.

I swear these things seem way larger than the gator skins. They almost feel like a 28mm. They just barely fit. There is only about 5mm of clearance between the tire and the seat stay cross brace. They also feel much 'softer' at 100psi then either the gatorskin or the zaffiro pro.

Seems like the rubber is VERY tacky when new as well. These things were picking up small rocks and flinging them against my frame and shooting them out in front of my bike. Kind of like running over some fresh road tar in a car. Very odd.


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## brucew (Jun 3, 2006)

A frequent complaint about Continentals has always been that they run small for their indicated size. This seems to have been reversed with the 25mm 4000S. I don't have calipers to measure, but mine also look bigger than my other 25mm Contis, and nearly the size of the 28mm GrandPrix 4-Seasons on my commuter.

As for the ride, remember that Gatorskins are a pretty stiff tire. Darned near anything will be more supple and thereby feel more comfortable. I equipped my first road bike with 25mm Gatorskins. I always thought that bike rode rough, until I wore out the tires and replaced them with GrandPrix 4-Seasons. It wasn't the bike that rode rough, it was the tires.


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## NealH (May 2, 2004)

I have measured my 4000 25's, and they consistently run between 26 and 26.5mm. I like them.


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## Sisophous (Jun 7, 2010)

I just put two new Continental GP4000s tires (25mm) on my bike last night. I would not say they run large, they actually are tough to mount. I recently picked up a Kool Stop Tire Bead Jack and it made a huge difference in mounting these tires. My last tires were the GP4000 (no "s") and I think those were even slightly smaller. Not sure this matters much but the new tires seem to look smaller on my bike than my worn ones that I removed. I suppose when you break them in they flatten out somewhat. 

The largest size tire I can take is 25 mm for clearance issues. I actually would have gone with a 28 mm if it would have fit. Your post is helpful to me in that in the future I will avoid the Gator Skins if they seem smaller than the Continentals. 

And yes, the rubber is slightly tacky when new but they will be as smooth as silk once you put a couple thousand miles on them. I can't tell a difference in the ride between a new tire and my old ones.


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## SauronHimself (Nov 21, 2012)

And right now Wiggle has them priced at $35.82 USD apiece. For the 25mm version that's a steal.

Wiggle | Continental Grand Prix 4000S Road Tyre | Road Race Tyres


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## Cyclin Dan (Sep 24, 2011)

I'm about 230lbs and always run 23mm tires at high PSI. I've been giving consideration to trying done 25mm. 

I always run GP4000S these days.


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## looigi (Nov 24, 2010)

Note: The installed width of the tire will be influenced by the width of the rim. Tires that 23 and 25 mm wide on traditional 19mm rims wind up about 25 and 27.5 mm respectively installed on 23mm wide rims.


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## c_h_i_n_a_m_a_n (Mar 3, 2012)

Just did a quick measure on my 4000s and they were 27.0mm wide. The 4 Seasons were 26.5mm.

This is for 25mm tyres on 20mm external width rims.

_Mounting: I always use a bit of dish washing liquid on damp cloth and go around the rim edge and tyre bead to help._


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## vagabondcyclist (Apr 2, 2011)

They run smaller (and thus truer to size) than the Michelin Krylion 25mm tires I had last year.


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> I'm about 230lbs and always run 23mm tires at high PSI. I've been giving consideration to trying done 25mm.
> 
> I always run GP4000S these days.


25? you should be on 28mm tires. at 100psi tops. for real. explain to us how 23mm tires at (how high?) pressure make sense, please. 

i mounted a 4000s on an A23 today and it was 26.6mm wide. the 25mm Pro4 SC they guy had on that wheel was 28.9mm wide. rubbed the chainstays while out of the saddle on a Cervelo R5.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> 25? you should be on 28mm tires. at 100psi tops. for real. explain to us how 23mm tires at (how high?) pressure make sense, please.
> 
> i mounted a 4000s on an A23 today and it was 26.6mm wide. the 25mm Pro4 SC they guy had on that wheel was 28.9mm wide. rubbed the chainstays while out of the saddle on a Cervelo R5.


I run about 120 PSI. 

Explain how it makes sense? I can't explain it, that's just what I do. Over the past 3 years I've logged over 20,000 miles that way. Works fine, but I don't know any different.


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## Sisophous (Jun 7, 2010)

cxwrench said:


> 25? you should be on 28mm tires. at 100psi tops. for real. explain to us how 23mm tires at (how high?) pressure make sense, please.


I tend to agree with the above statement. I went from 23 to 25 and it made a major difference in not getting flats and a faster, more comfortable ride. I used to ride on my old bike size 28 which is what I would prefer now but my present bike can't clear size 28 with the frame. 

Check if you can clear a 28 with your frame and if so, go with it. As a larger size guy you should feel a major difference in ride quality with a larger size tire and filling them with slightly less pressure.

There is no right or wrong to this topic, it is what is most comfortable while out riding and the poster who suggested size 28 and at 100 psi sounds spot on right. To each his own.


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## Cyclin Dan (Sep 24, 2011)

Sisophous said:


> I tend to agree with the above statement. I went from 23 to 25 and it made a major difference in not getting flats and a faster, more comfortable ride. I used to ride on my old bike size 28 which is what I would prefer now but my present bike can't clear size 28 with the frame.
> 
> Check if you can clear a 28 with your frame and if so, go with it. As a larger size guy you should feel a major difference in ride quality with a larger size tire and filling them with slightly less pressure.
> 
> There is no right or wrong to this topic, it is what is most comfortable while out riding and the poster who suggested size 28 and at 100 psi sounds spot on right. To each his own.


I don't know if I can clear 28's...I have an S-Works Tarmac SL3. 

I'll order 25's next time because I know the tire I like is available and fits my bike. What PSI would you all recommend in those?


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## JM714 (Jan 22, 2004)

I was running 25mm GP4000s on an old Campagnolo rim (Omega) on a CAAD 10 frame. They fit great. I then got a new wheelset built with Kinlin XC279 rims and put the GP's on. The front wouldn't clear the fork. They looked huge. I had to go to 23mm GP's.

I haven't measured them to see what their dimensions are.


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> I don't know if I can clear 28's...I have an S-Works Tarmac SL3.
> 
> I'll order 25's next time because I know the tire I like is available and fits my bike. What PSI would you all recommend in those?


how are the roads you normally ride on? if they're good/smooth, then try 100rr/90frt to start. do you run over crap all the time? do you hit every pothole in the road? if so, add a little pressure. if not, try what i suggested before. i know guys your size that run as low as 95rr/80frt on 25mm tires and don't have any problems. the roads here in the north bay area aren't great, but they're not exactly 'bad'. 
i know 23mm tires and 120psi are 'all you know', but now you have some different input. try this and see what you think. give it a week or 3. honestly, do you really think that you at 230 lbs and a 115 lb woman or kid should be riding on the same tire? does that make sense?


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## SantaCruz (Mar 22, 2002)

Cyclin Dan said:


> What PSI would you all recommend in those?


I'm a shade over 200 and mostly ride 25mm tires. 100-105psi on gentler rides. 110 - 115 for longer, faster rides or if the pavement is rough. 

If the day's ride has a lot of chipseal or sections of dirt road, I take the bike that accepts 28mm on the rear and run about 105psi.

For tubulars about 120.


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## kbwh (May 28, 2010)

Listen to cxwrench and do what he tells you. 

cxwrench, you've been repped.


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## chudak (Jul 28, 2012)

Thanks for the input guys. I run 25s because I'm a heavier guy like Cyclin Dan (~240lb). As I mentioned, I never had a clearance problem with the Conti Gator Skins or the Vittorias, both in a 25mm. Although these new tires are 'plush' I don't like the minimal clearance and the fact that they hang up on the brake pads when I'm removing them. I measured them with a set of calipers and they look to be about 26.5mm. It would appear that the 23mm GP 4000s might end up fitting like the 25mm gator skins. I might give those a go on my next tire change.

As for cxwrenches psi comments: I normally run my 25s at about 105-110. I ride mixed quality roads. This pressure prevents me from getting pinch flats and itsn't so hard to beat me up too bad.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> how are the roads you normally ride on? if they're good/smooth, then try 100rr/90frt to start. do you run over crap all the time? do you hit every pothole in the road? if so, add a little pressure. if not, try what i suggested before. i know guys your size that run as low as 95rr/80frt on 25mm tires and don't have any problems. the roads here in the north bay area aren't great, but they're not exactly 'bad'.
> i know 23mm tires and 120psi are 'all you know', but now you have some different input. try this and see what you think. give it a week or 3. honestly, do you really think that you at 230 lbs and a 115 lb woman or kid should be riding on the same tire? does that make sense?


I appreciate all the help/input on this. I live in Utah, so there's a fair bit of chip seal and cracked/pothole riddled roads, but many of them are perfectly smooth. I try to avoid road hazards (don't we all?) but it isn't always possible to. 

I ordered a pair of GP4000S from Wiggle in 25mm width. I'll give then a go when they show up...I'll try the suggested pressure. I just don't want to figure out it's too little pressure by breaking a wheel, you know what I'm saying? How do you know when you have too little pressure?


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## cxwrench (Nov 9, 2004)

SantaCruz said:


> I'm a shade over 200 and mostly ride 25mm tires. 100-105psi on gentler rides. 110 - 115 for longer, faster rides or if the pavement is rough.
> 
> If the day's ride has a lot of chipseal or sections of dirt road, I take the bike that accepts 28mm on the rear and run about 105psi.
> 
> *For tubulars about 120*.



why 120? 


chudak said:


> Thanks for the input guys. I run 25s because I'm a heavier guy like Cyclin Dan (~240lb). As I mentioned, I never had a clearance problem with the Conti Gator Skins or the Vittorias, both in a 25mm. Although these new tires are 'plush' I don't like the minimal clearance and the fact that they hang up on the brake pads when I'm removing them. I measured them with a set of calipers and they look to be about 26.5mm. It would appear that the 23mm GP 4000s might end up fitting like the 25mm gator skins. I might give those a go on my next tire change.
> 
> As for cxwrenches psi comments: I normally run my 25s at about 105-110. I ride mixed quality roads. This pressure prevents me from getting pinch flats and itsn't so hard to beat me up too bad.


that sounds pretty reasonable for a guy your size. how wide are the rims you're running and do you by chance like your brakes adjusted on the tight side? if you're using narrowish rims w/ wide tires you'll get the tire hanging up on the rim when you remove the wheel. obviously if you like your brakes 'tight' (which i can't stand) it will happen. the way i set up my brakes i never have to open the brake to get the tire between the pads. i find that lots and lots of people have their brakes very very tight, they probably don't even realize it because some know-not mechanic set them up that way and they don't know any better. it's much better IMO to have more lever movement as you have more ability to modulate braking power, instead of your brake levers becoming an on/off switch. also your hands and forearms will tire less quickly if you can pull the lever closer to the bar rather than it being far away from the bar.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> why 120?
> 
> 
> that sounds pretty reasonable for a guy your size. how wide are the rims you're running and do you by chance like your brakes adjusted on the tight side? if you're using narrowish rims w/ wide tires you'll get the tire hanging up on the rim when you remove the wheel. obviously if you like your brakes 'tight' (which i can't stand) it will happen. the way i set up my brakes i never have to open the brake to get the tire between the pads. i find that lots and lots of people have their brakes very very tight, they probably don't even realize it because some know-not mechanic set them up that way and they don't know any better. it's much better IMO to have more lever movement as you have more ability to modulate braking power, instead of your brake levers becoming an on/off switch. also your hands and forearms will tire less quickly if you can pull the lever closer to the bar rather than it being far away from the bar.


I run 19mm wide rims. I don't have my brakes set very tight, I am with you there. I'm not that worried about having to relieve some pressure from the tires before removing my wheels either (although I don't think it will be a problem)...I typically only do that when I have a flat or need to work on the bike. I don't remove the wheels to store or transport. 

So...how do I know that optimal pressure point? I want to find out it's too little by breaking an expensive wheel...


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## chudak (Jul 28, 2012)

cxwrench said:


> w
> that sounds pretty reasonable for a guy your size. how wide are the rims you're running and do you by chance like your brakes adjusted on the tight side? if you're using narrowish rims w/ wide tires you'll get the tire hanging up on the rim when you remove the wheel. obviously if you like your brakes 'tight' (which i can't stand) it will happen. the way i set up my brakes i never have to open the brake to get the tire between the pads. i find that lots and lots of people have their brakes very very tight, they probably don't even realize it because some know-not mechanic set them up that way and they don't know any better. it's much better IMO to have more lever movement as you have more ability to modulate braking power, instead of your brake levers becoming an on/off switch. also your hands and forearms will tire less quickly if you can pull the lever closer to the bar rather than it being far away from the bar.


I'm running CXP-22's. Yeah, I do run my brakes on the 'tight' side. I spend most of my time on the hoods not the drops and I find tighter brakes easier to deal with on the hoods. If I spent more time on the drops I could see your point regarding lever travel. I do see the modulation point...but even running kool stop black pads, with my size I have to put a fair amount of pressure on the brakes to lock them up. It would be totally different if I was a buck fifty.


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## dcgriz (Feb 13, 2011)

Cyclin Dan said:


> So...how do I know that optimal pressure point? I want to find out it's too little by breaking an expensive wheel...


I don't agree with all of JH's beliefs/preferences but I do find this accurate about optimizing pressure points
Link: http://www.bikequarterly.com/images/TireDrop.pdf


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## cxwrench (Nov 9, 2004)

SantaCruz said:


> I'm a shade over 200 and mostly ride 25mm tires. 100-105psi on gentler rides. 110 - 115 for longer, faster rides or if the pavement is rough.
> 
> If the day's ride has a lot of chipseal or sections of dirt road, I take the bike that accepts 28mm on the rear and run about 105psi.
> 
> For tubulars about 120.





chudak said:


> Thanks for the input guys. I run 25s because I'm a heavier guy like Cyclin Dan (~240lb). As I mentioned, I never had a clearance problem with the Conti Gator Skins or the Vittorias, both in a 25mm. Although these new tires are 'plush' I don't like the minimal clearance and the fact that they hang up on the brake pads when I'm removing them. I measured them with a set of calipers and they look to be about 26.5mm. It would appear that the 23mm GP 4000s might end up fitting like the 25mm gator skins. I might give those a go on my next tire change.
> 
> As for cxwrenches psi comments: I normally run my 25s at about 105-110. I ride mixed quality roads. This pressure prevents me from getting pinch flats and itsn't so hard to beat me up too bad.





Cyclin Dan said:


> I run 19mm wide rims. I don't have my brakes set very tight, I am with you there. I'm not that worried about having to relieve some pressure from the tires before removing my wheels either (although I don't think it will be a problem)...I typically only do that when I have a flat or need to work on the bike. I don't remove the wheels to store or transport.
> 
> So...how do I know that optimal pressure point? I want to find out it's too little by breaking an expensive wheel...


you prevent breaking expensive wheels by keeping your eyes open. i will never understand basically overinflating tires to prevent the once or twice a year pinch flat (that may or may not damage your rim) that could be prevented by looking out where you're going. what you're doing is spending 99.9999% of your time riding on tires w/ too much pressure trying to avoid something that happens .0001% of the time. would your wear a rain coat in july because there is the slimmest chance of it raining even there isn't a cloud in the sky? inflate your tires to the pressure that provides the ride you want on the roads you ride. then, look at the road so you know what's coming and can avoid anything that might damage your wheels.

still wondering why santa cruz pumps his tubulars up to 120...that makes no sense either.


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## TomH (Oct 6, 2008)

cxwrench said:


> how are the roads you normally ride on? if they're good/smooth, then try 100rr/90frt to start. do you run over crap all the time? do you hit every pothole in the road? if so, add a little pressure. if not, try what i suggested before. i know guys your size that run as low as 95rr/80frt on 25mm tires and don't have any problems. the roads here in the north bay area aren't great, but they're not exactly 'bad'.
> i know 23mm tires and 120psi are 'all you know', but now you have some different input. try this and see what you think. give it a week or 3. honestly, do you really think that you at 230 lbs and a 115 lb woman or kid should be riding on the same tire? does that make sense?


At my worst I was 220lb (now more like 185 ). Ran 23's and 25's at all varying pressures.

Honestly, its not even half as big of a deal as you're making it out to be. I stuck with the 25's because they ride a little smoother, but really not that much smoother. Its still a fully rigid bike on tiny tires and high pressures. If someone wants to ride 23c's at 120psi, well I guess have at it. Its not really any slower or faster than lower pressure 25's. Its not THAT much more uncomfortable either.


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## cxwrench (Nov 9, 2004)

TomH said:


> At my worst I was 220lb (now more like 185 ). Ran 23's and 25's at all varying pressures.
> 
> Honestly, its not even half as big of a deal as you're making it out to be. I stuck with the 25's because they ride a little smoother, but really not that much smoother. Its still a fully rigid bike on tiny tires and high pressures. If someone wants to ride 23c's at 120psi, well I guess have at it. Its not really any slower or faster than lower pressure 25's. Its not THAT much more uncomfortable either.


no, it's not really any faster at all. but...
you'll have much better traction and the difference in ride is accepted by the VAST majority of riders to be much better. 
and it's free and ridiculously easy. why wouldn't you try it?


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## bikerjulio (Jan 19, 2010)

Back to the original question - with my answer being no.

I have three bikes with 25mm tires - Mich. PR4, Mich. Optimum, and Conti GP4000. All 19mm rims. At 90psi for all, the Conti's are a fraction under 25mm, the Optimum rear is dead on (front is about 0.5mm under), and the PR4's are about 0.5mm over.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> no, it's not really any faster at all. but...
> you'll have much better traction and the difference in ride is accepted by the VAST majority of riders to be much better.
> and it's free and ridiculously easy. why wouldn't you try it?


So you really believe I wool experience improved traction? To me, it seems like the squishier the tire gets, the more rolling resistance is created and this the slower you well be. The exception of course being extreme examples...things like a Top Fuel Dragster where they desperately need the traction.


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> So you really believe I wool experience improved traction? To me, it seems like the squishier the tire gets, the more rolling resistance is created and this the slower you well be. The exception of course being extreme examples...things like a Top Fuel Dragster where they desperately need the traction.


so you're going to ignore the dozens of posts on this exact subject where many, many knowledgeable people say the EXACT same thing i'm saying? 
if your tire is near max allowable pressure, yes...you have reduced the available mechanical grip. there is LESS flex in the casing to absorb cornering forces and surface imperfections. this is a fact. 
if your tires is near max pressure it is bouncing up and down over said surface imperfections, this is known as 'it sure _feels_ fast'. obviously, if it's going up and down so is the bike and the rider. which also means they're not going forward as efficiently as possible. this DEFINES 'rolling resistance'. somewhat lower pressure will allow some flex in the casing of the tire and absorb these imperfections and allow you to roll w/ less resistance. remember, the tire is the ONLY suspension on a road bike. 
if you lowered the pressure to 40 or 50psi, yes...you'd create more resistance due to flex of the tire casing (known as 'hysteresis'), but you're not going that low. 
the reference to top fuel drag tires is interesting but at the extreme opposite end of the pressure/traction spectrum. they run 6.5-7.5psi and rolling resistance is not even considered. 
yes, i believe you will experience improved traction. you think i'd waste all this time and effort telling people they're doing it wrong if it didn't make any difference?


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> so you're going to ignore the dozens of posts on this exact subject where many, many knowledgeable people say the EXACT same thing i'm saying?
> if your tire is near max allowable pressure, yes...you have reduced the available mechanical grip. there is LESS flex in the casing to absorb cornering forces and surface imperfections. this is a fact.
> if your tires is near max pressure it is bouncing up and down over said surface imperfections, this is known as 'it sure _feels_ fast'. obviously, if it's going up and down so is the bike and the rider. which also means they're not going forward as efficiently as possible. this DEFINES 'rolling resistance'. somewhat lower pressure will allow some flex in the casing of the tire and absorb these imperfections and allow you to roll w/ less resistance. remember, the tire is the ONLY suspension on a road bike.
> if you lowered the pressure to 40 or 50psi, yes...you'd create more resistance due to flex of the tire casing (known as 'hysteresis'), but you're not going that low.
> ...


Hey man, calm down. I'm not ignoring you, I just asked a question. Obviously I'm not ignoring you, I said I just ordered tires in that size. 

Again, I appreciate the input. I was just asking a question, that's all. Nobody is ignoring you.


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## Every_Hill_is_4_Cadel (Feb 8, 2014)

*23 is a Ferrari and 25 is the Rolls*



Cyclin Dan said:


> Hey man, calm down. I'm not ignoring you, I just asked a question. Obviously I'm not ignoring you, I said I just ordered tires in that size.
> 
> Again, I appreciate the input. I was just asking a question, that's all. Nobody is ignoring you.


I find the 25 a bit squishy on higher stress corners compared to the 23. It seems to wallow a bit, even at pressures towards the top of the recommended range.

Next time, if I stick to the Contis, I'll probably go back to 23s


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