# Conti GP4000S II - strange front tire blowout - wanted to share



## defboob (Aug 31, 2011)

So i've got around 200 mi on these tires (700x25 on CAAD10) and things were great, was really enjoying them - when on today's ride, I was just finishing up 30+ miles and i started to hear a strange sound from my front tire. As i began to slow down and pull off to see what was up, the tire just went KA-POW and was finished - blew out from the side. See below for a picture of what it looks like. Somehow the wire bead blew out the side and went outside of the rim walls, very strange. Anyone ever have this happen to them? Defective tire? I don't get it. It was inflated to 90psi, i'm about 170lbs - and i've had a good bit of riding on them so far with no issues, including a century ride. Thank goodness it didn't happen earlier on the ride in a spot that could have been way more dangerous, i was right near my neighborhood where i was just finishing up, so i just had to do the walk of shame home. Just curious to hear any insight from others - as far as I can tell i had it installed correctly and had a good bit of hard miles without issue.


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## MJCBH (Nov 25, 2002)

Exact same thing happened to my sister-in-law the other day. I'm not sure if her tires were GP4000SII or a previous model. They were pretty much new tires as well. Conti did warranty them after they returned them to the shop where they purchased them. I've ridden Conti's for a few years but will be switching brands because of numerous problems with weak sidewalls. Quality control seems very inconsistent with Conti (ie- some of my previous tires lasted for quite some time with little flats while others had sidewall blowouts or excess wear on the sidewall pre-maturely after just a few hundred miles). Too bad to hear the quality didn't improve much with the new 4000S II model.


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## upstateSC-rider (Aug 21, 2004)

Here come the conti-lovers saying that you hit a rock or installed it wrong or soaked the tire in hydrochloric acid, blah, blah. Anything but the truth which is way too many people have had problems with them, and this coming from a former conti-lover.
Glad you kept it upright.


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## ericm979 (Jun 26, 2005)

I don't see a picture. 

If the bead blew over the rim but is still connected to the tire, most likely you pinched the tube under the bead. Sometimes you can ride for quite a while with that before the tube fails. When it does it blows explosively and blows the bead over the edge of the rim. 

If the bead seperated from the tire, the tire was defective (or you damaged the bead while installing it, but you have to be pretty rough to do that).


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## spdntrxi (Jul 25, 2013)

my wife had that happen to a v1 of the 4000s... we both use v2 now.. and her bike has a few hundred miles and I probably have 5-600 hundred with no issue. The one that blew was 6 miles old.

when her's blew the bead was still connected to the tire.. not like yours.


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## OldChipper (May 15, 2011)

upstateSC-rider said:


> Here come the conti-lovers saying that you hit a rock or installed it wrong or soaked the tire in hydrochloric acid, blah, blah. Anything but the truth which is way too many people have had problems with them, and this coming from a former conti-lover.
> Glad you kept it upright.


And here come the Conti haters insisting that tires should last forever no matter what sort of road debris they hit or installation errors they make and insisting that any non-zero number of failures in one of the most popular tires in use today means they're all crap.


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## ericm979 (Jun 26, 2005)

Ok now I see it. Probably defective.

I've had that happen once, on a michelin. It was suggested that I may have damaged the bead when I remove the tire- at the time I would get enough of the bead loose then strip the rest of the tire of by running the lever around the rim. On modern tires there isn't a lot of material there.

I'd installed and removed that tire a couple times and it was on a very tight rim so I'd been levering pretty hard on it. I try to be gentler on tires since then, and don't strip the tire off with the lever when it's still tight on the rim.

I also use thinner levers- either the thin Conti ones which are impossible to find in the US, or the new Park TL4s. They're gentler on tires.


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## Audley_Yung (Aug 9, 2013)

I think the recommended tire pressure for someone your weight is 120psi...


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## Blue CheeseHead (Jul 14, 2008)

Let me first state that for a standard clincher I love the 4000s and it was my tire of choice until I went tubeless. That said, I have sold thousands of sets of tires over the past few years and the 4000s is by far the one that I saw the most warranty (defective tire) claims. It may have been 3 or 4 tires per thousand. The bead separation is a defect and not due to a road hazard.


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## jpaschal01 (Jul 20, 2011)

Audley_Yung said:


> I think the recommended tire pressure for someone your weight is 120psi...


Actually recommended tire pressure for that tire is 95 to 120 psi. At 170 pounds, he is nowhere near the max. And depending on his rim width, he may be able to go below the minimum recommended pressure.


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## defboob (Aug 31, 2011)

Thanks guys, yes these tires on on FLO 30 rims which are wide so 90psi feels great on them. I can't imagine 120psi that seems extremely high. The good news is that I got my replacement tire compensated, and i've been on them ever since without any issues, riding well again. Let's hope it stays that way!


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## bikerjulio (Jan 19, 2010)

Audley_Yung said:


> I think the recommended tire pressure for someone your weight is 120psi...


Ridiculous.

OP is running 25mm tires on a wide rim, so effectively 28mm, which is the same setup I have on a couple of bikes

I'm 200#

Through trial and error I've settled on 75psi front and 90 rear, which happens to coincide exactly with the recommendation given by this calculator for a total of 220# and 45/55 weight distribution.

Being 30# lighter than me the OP could go to 65psi front and 80 rear.

Bicycle tire pressure calculator

It's a noob thing to think that higher pressure is better - I was one once. If 120 is good then 140 must be better - right? I was also in a group when one over-pumper had his front tire explode, causing a nasty crash, numerous broken bones, and several months off the bike for the pumper.


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## shokhead (Dec 17, 2002)

*yite*

23's/93 in front/113 on rear. Almost 3k on rear. No problems with 4000s


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## dracula (Mar 9, 2010)

defboob said:


> Thanks guys, yes these tires on on FLO 30 rims which are wide so 90psi feels great on them. I can't imagine 120psi that seems extremely high. The good news is that I got my replacement tire compensated, and i've been on them ever since without any issues, riding well again. Let's hope it stays that way!



Swap it out for Continental Gatorskins where they have a much stronger and stouter sidewall and last > 5000 km; I often ride on gravel roads and my tyre pressure is 6 bar rear and 5 bar front.

I claim my Gatorskins 25 mm non-folding rear and 25 mm folding front gives me a smoother ride than my 24 mm Conti Grand Prix GP (the 24 mm Conti GP and 25 mm Gatorskin measure the same laid flat: 65 mm). Forget thread count and all the other crap; although on another bike the most uncomfortable tyre I ever had the displeasure to ride with was a green Vittoria Open Pave 24 mm with 320 tpi (threads per inch).

By the way: I just had a sidewall failure last Friday on the front on my GP 24 mm. I often rotate between the Continental Gatorskins and Continental Grand Prix.


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## BruiserBob (Apr 13, 2005)

had the same failure. I feel lucky to be alive since the sidewall failed on a descent


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## Migen21 (Oct 28, 2014)

What specific tire model is that?


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## Mackers (Dec 29, 2009)

Sure doesn't look like a 4000S


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## BruiserBob (Apr 13, 2005)

Continental Grand Prix 4 Season


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## Lombard (May 8, 2014)

bikerjulio said:


> Ridiculous.
> 
> OP is running 25mm tires on a wide rim, so effectively 28mm, which is the same setup I have on a couple of bikes
> 
> ...



^^^This^^^



> You must spread some Reputation around before giving it to bikerjulio again.


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## Lombard (May 8, 2014)

After seeing all this, I'll definitely stick with my bombproof Maxxis Refuses!


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## Migen21 (Oct 28, 2014)

Lombard said:


> After seeing all this, I'll definitely stick with my bombproof Maxxis Refuses!


The Maxxis Re-Fuse is a $25 60 TPI multi-use file thread tire.

The 4 Season is a 320 TPI training/road tire. 

They are not really in the same class.


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## dracula (Mar 9, 2010)

defboob said:


> So i've got around 200 mi on these tires (700x25 on CAAD10) and things were great, was really enjoying them - when on today's ride, I was just finishing up 30+ miles and i started to hear a strange sound from my front tire. As i began to slow down and pull off to see what was up, the tire just went KA-POW and was finished - blew out from the side. See below for a picture of what it looks like. Somehow the wire bead blew out the side and went outside of the rim walls, very strange. Anyone ever have this happen to them? Defective tire? I don't get it. It was inflated to 90psi, i'm about 170lbs - and i've had a good bit of riding on them so far with no issues, including a century ride. Thank goodness it didn't happen earlier on the ride in a spot that could have been way more dangerous, i was right near my neighborhood where i was just finishing up, so i just had to do the walk of shame home. Just curious to hear any insight from others - as far as I can tell i had it installed correctly and had a good bit of hard miles without issue.



Contis are world renowed for tyre blow-outs. You are not alone.

Btw: Don't make the mistake and buy a Schwalbe.

On the othere side: I haven't handled a GP4000S II but assume it is a race tyre with 1. paper-thin sidewalls, 2. zero rubber and 3. zero puncture protection. Such a tyre works in Disneyland but not on real roads.


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## goodboyr (Apr 19, 2006)

Oy........so much ass umption......


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## ericm979 (Jun 26, 2005)

I've seen this type of blowout twice now, one on my wheel and one on a team mate's. Both were Michelin and on carbon clinchers on a descent. I think that there are two factors that can cause or encourage this- rim heat and damage to the bead from poor mounting technique. As I posted above in 2014 I think my blowout was mostly from damaging the bead during installation (and one removal) by sliding the tire iron along the rim to remove the tire.

But I think that rim heat can also be a cause or contributor. Carbon clinchers are known to heat the tire bead area as it's close to the braking surface. 

GP4000S tires are quite durable for a race tire, lasting about twice as long as other race tires I've used. I use them all year round for training.


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## Oxtox (Aug 16, 2006)

dracula said:


> On the othere side: I haven't handled a GP4000S II but assume it is a race tyre with 1. paper-thin sidewalls, 2. zero rubber and 3. zero puncture protection. Such a tyre works in Disneyland but not on real roads.


an imagined description of a tire you've never used is greatly appreciated.

adds much to the discussion.


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## Lombard (May 8, 2014)

Migen21 said:


> The Maxxis Re-Fuse is a $25 60 TPI multi-use file thread tire.


Huh? Every description I've seen, this is a road/training tire.



Migen21 said:


> The 4 Season is a 320 TPI training/road tire.
> 
> They are not really in the same class.


I fail to see what makes the Conti GP4000S II "4 season tires". They look like slicks to me.

IMHO, I would rather have a lower TPI bulletproof tire, than a more supple higher TPI tire.


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## cobra_kai (Jul 22, 2014)

Lombard said:


> I fail to see what makes the Conti GP4000S II "4 season tires". They look like slicks to me.
> 
> IMHO, I would rather have a lower TPI bulletproof tire, than a more supple higher TPI tire.


The Continental GP4000s II is a different tire than the Continental GP 4 Season. The 4000s II is more towards a race tire, although it still does have some puncture protection. Continentals pure race tires are more like the GP Time Trial or Supersonic. The 4 season is what they describe as an all season durable tire. Continental Grand Prix 4 Season Rolling Resistance Review


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## tlg (May 11, 2011)

Lombard said:


> I fail to see what makes the Conti GP4000S II "4 season tires". They look like slicks to me.


The GP4000S and 4 Season are two different tires.

The 4 seasons are pretty bullet proof. Almost as much so as Gatorskins. I use them for winter and gravel riding.

Grand Prix 4 Season - conti-tyres.co.uk


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## dracula (Mar 9, 2010)

Oxtox said:


> an imagined description of a tire you've never used is greatly appreciated.
> 
> adds much to the discussion.


So you are saying the Conti is not a race tyre?

I mean I don't need to take heroin or LSD or whatever to be able to state a-priori the following: "that heroin is not good for your body".

It is simply a fact that the OP is not the first one with a Conti tyre blowout.


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## goodboyr (Apr 19, 2006)

dracula said:


> So you are saying the Conti is not a race tyre?
> 
> I mean I don't need to take heroin or LSD or whatever to be able to state a-apriori the following: "that heroin is not good for your body".
> 
> It is simply a fact that the OP is not the first one with a Conti tyre blowout.


All three of the points you "ass u med" are factually incorrect. Other than that you are right.....


dracula said:


> Contis are world renowed for tyre blow-outs. You are not alone.
> 
> Btw: Don't make the mistake and buy a Schwalbe.
> 
> On the othere side: I haven't handled a GP4000S II but assume it is a race tyre with 1. paper-thin sidewalls, 2. zero rubber and 3. zero puncture protection. Such a tyre works in Disneyland but not on real roads.


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## Oxtox (Aug 16, 2006)

dracula said:


> So you are saying the Conti is not a race tyre?


what I'm saying is that you're talking out your ass about a tire you've apparently never even seen.

quit while you're behind.


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## woodys737 (Dec 31, 2005)

ericm979 said:


> I've seen this type of blowout twice now, one on my wheel and one on a team mate's. Both were Michelin and on carbon clinchers on a descent. I think that there are two factors that can cause or encourage this- rim heat and damage to the bead from poor mounting technique. As I posted above in 2014 I think my blowout was mostly from damaging the bead during installation (and one removal) by sliding the tire iron along the rim to remove the tire.
> 
> But I think that rim heat can also be a cause or contributor. Carbon clinchers are known to heat the tire bead area as it's close to the braking surface.
> 
> *GP4000S tires are quite durable for a race tire, lasting about twice as long as other race tires I've used. I use them all year round for training.*


+1. I've found the same thing and run them year around down here in Phoenix. I think they handle the heat better than most tires. Given the crr is close to the best and after some bad experience now with Specialized Turbo cottons I'm back to using these for training and racing.


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## SauronHimself (Nov 21, 2012)

dracula said:


> On the othere side: I haven't handled a GP4000S II but assume it is a race tyre with 1. paper-thin sidewalls, 2. zero rubber and 3. zero puncture protection. Such a tyre works in Disneyland but not on real roads.


You know what they say about assuming...

I've had a good handful of GP4000S tires, and I can make a rear last 3500 miles easily. The sidewalls are also normal thickness. I have experienced only a single flat on this tire, whereas I got three punctures last fall on the same Michelin Pro 4 Endurance.


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## dracula (Mar 9, 2010)

SauronHimself said:


> You know what they say about assuming...
> 
> I've had a good handful of GP4000S tires, and I can make a rear last 3500 miles easily. The sidewalls are also normal thickness. I have experienced only a single flat on this tire, whereas I got three punctures last fall on the same Michelin Pro 4 Endurance.


Oh Jesus! Someone on the internet was wrong.

I apologise: I don't assume the Contis are race tyres with paper thin sidewalls, zero rubber and zero puncture protection. I for all claim and state the aforementioned as a fact. No assuming any more - we are talking about facts.

Amigos come on: I am a victim myself on my low spoke count wheels. You don't wanna know what all has been assumed here in the 'Wheels and Tires' section, about factory low spoke count wheelsets.


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## goodboyr (Apr 19, 2006)

Lol. Who cares. I've been using them for years without an issue.


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## Migen21 (Oct 28, 2014)

Dracula, you are talking about 'Contis' like it's one tire. Continental has a HUGE variety of tires. They make tires of every possible variety for every situation. From pro race tires down to the heaviest duty gravel and MTB tires. 

They have 13 tires that fit into the 'Road->Race->Clincher' category alone. 

Continental bicycle tyres

Some of these tires are designed specifically for winter training, rough roads, puncture resistance and good grip in poor conditions, at the cost of being heavy (and in some cases expensive). Others are specifically designed to be dedicated lightweight race tires that probably wouldn't hold up on a daily gravel ride.i 

Oh, and by the way, they also happen to be a large manufacturer of car tires as well.

Continental


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## dracula (Mar 9, 2010)

Migen21 said:


> Dracula, you are talking about 'Contis' like it's one tire. Continental has a HUGE variety of tires. They make tires of every possible variety for every situation. From pro race tires down to the heaviest duty gravel and MTB tires.
> 
> They have 13 tires that fit into the 'Road->Race->Clincher' category alone.
> 
> ...


I was always talking about the OP's tyre.

I tell you the truth: I have been using a Gatorskin rear tyre on my commuter for some time without any problem. I even happen to be using Contis on my summer bike in the Alps.

But this doesn't take away from the fact that OP's tyre system is a race tyre system. 

I have no dog in the fight (probably the worst the OP now could do is to get out and treat himself a Schwalbe race tyre).

PS: I loved the Michelin Krylion and Pro Endurance tyres. However, Michelin Pro3 Race were crap with paper thin sidewalls and zero puncture protection (like the Conti ones in OP's post) and didn't take long until a bulge developed (on a summer bike).


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## ericm979 (Jun 26, 2005)

The GP4000s does have a puncture protection layer. 
But OP did not have a puncture, he had the bead pull out of the tire.


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## SauronHimself (Nov 21, 2012)

dracula said:


> Oh Jesus! Someone on the internet was wrong.
> 
> I apologise: I don't assume the Contis are race tyres with paper thin sidewalls, zero rubber and zero puncture protection. I for all claim and state the aforementioned as a fact. No assuming any more - we are talking about facts.
> 
> Amigos come on: I am a victim myself on my low spoke count wheels. You don't wanna know what all has been assumed here in the 'Wheels and Tires' section, about factory low spoke count wheelsets.


That back pedal was so hard it could track stand a freewheel.


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## thumper8888 (Apr 7, 2009)

goodboyr said:


> Lol. Who cares. I've been using them for years without an issue.


ding ding ding, winner.
+1
I've got more than 20,000 miles on 4000s and 4000sII and yeah, I lose one every four months or so to a large, sharp rock hit off center because yes, the sidewalls are thin.
So what?
If the sidewalls aren't thin, tires can't be fast. It's straightforward physics about the force it takes to bend stuff.
If you can't make the tradeoffs it takes to go fast, don't do it, but quit clogging the forum with cries about tires needing to be bombproof, how the manufacturer should be taken outside and shot etc.
GP4000s's are really really robust for what they are, which is pretty much the fastest clincher there is, or at least within a watt or so of of it. If you want to ride 20-30 watts slower because you enjoy feeling safe and that great "pedaling though deep sand feeling" slow, go right ahead, just don't brag about how you will never buy "flimsy" tires.


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## Lombard (May 8, 2014)

thumper8888 said:


> ding ding ding, winner.
> +1
> I've got more than 20,000 miles on 4000s and 4000sII and yeah, I lose one every four months or so to a large, sharp rock hit off center because yes, the sidewalls are thin.
> So what?
> ...


You lose one every 4 months to a large sharp rock? Really? Do you not see large sharp rocks before you hit them?

But so what? So what if a tire blows and lands you in the hospital. Just another day on the bike, right??


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## thumper8888 (Apr 7, 2009)

Of course I see those rocks. I just refuse to believe a proper bicycle tire won't handle them so i AIM RIGHT FOR THEM.
Seriously,
It might be hard to believe, but large groups of racers a few inches apart going really, really hard might not always be perfectly focussed on calling out rocks.
Four months avg is prob overstating it, probably longer. I'm just a little bitter about losing one two weeks ago to a two-inch chuck of pavement... just three hours after I bought it. Hammer ride, attack on, and someone didn't call it out.
Rock was big enough that it should have destroyed the rim, too, but somehow didn't.
Not the tire's fault. Not the manufacturer's fault. Not my fault.
Stuff happens.
Yes, just another day on the bike. I crash about 1 time out of every 30 races or so. I don't like it, especially since it has never been my fault. Nor has it been because of tires.
But it's the cost of doing business, and that's a normal stat for racing. That's what these tires are for, serious performance and racing, not commuting, not C group rides running 17 mph.
If you run them, you just accept that they aren't as robust as gatorskins etc.


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## Lombard (May 8, 2014)

thumper8888 said:


> .....because you enjoy feeling safe and that great "pedaling though deep sand feeling" slow......


Seriously?? A "pedaling though deep sand feeling" while riding training tires? Me thinks you may need to train a little harder.


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## thumper8888 (Apr 7, 2009)

Lombard said:


> Seriously?? A "pedaling though deep sand feeling" while riding training tires? Me thinks you may need to train a little harder.


And methinks:
1) Anyone who doesn't notice -- and mind -- when they are slogging along on tires that are costing 20-30 watts isn't training enough to know the difference between good tires and bad and
2) you need to quit worrying about me, i.e. whether I can see rocks, whether I'm training hard enough etc and either move on, or focus on the discussion of tires.
You don't know me, I don't know you and I won't really put up with gratuitous anonymous internet BS attacks. Got it?


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## Lombard (May 8, 2014)

thumper8888 said:


> And methinks:
> 1) Anyone who doesn't notice -- and mind -- when they are slogging along on tires that are costing 20-30 watts isn't training enough to know the difference between good tires and bad and
> 2) you need to quit worrying about me, i.e. whether I can see rocks, whether I'm training hard enough etc and either move on, or focus on the discussion of tires.
> You don't know me, I don't know you and I won't really put up with gratuitous anonymous internet BS attacks. Got it?


Lighten up Francis! Believe me, I'm not worrying about you.  I was just being snarky because you came in here like a testosterone charged bad a$$ racer who crashes here and there, but so what?? With this attitude, you're inviting BS attacks.  

I hardly consider my remarks attacking you. It's a joke son, move on.


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## thumper8888 (Apr 7, 2009)

Lombard said:


> Lighten up Francis! Believe me, I'm not worrying about you.  I was just being snarky because you came in here like a testosterone charged bad a$$ racer who crashes here and there, but so what?? With this attitude, you're inviting BS attacks.
> 
> I hardly consider my remarks attacking you. It's a joke son, move on.


Eating the normal percentage of crashes doesn't make me badass, it really says nothing about whether I'm any good at racing -- and I'm not, particularly -- just that they happen and there's nothing that can be done about it.
But point taken, thanks.


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## dmanthree (Aug 22, 2014)

This thread is unreal. A single tire failure from an unknown cause under unknown conditions and quite a few riders are ready to write off the brand? Really? OK, here's another data point: I've ridden these tires for about 30K over the last few years with only a couple of pinch flats. No failures, no blowouts, no problems. So I guess I should ignore the success I've had with them and dump them based on a single incident.

Sheesh...


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## BacDoc (Aug 1, 2011)

dmanthree said:


> This thread is unreal. A single tire failure from an unknown cause under unknown conditions and quite a few riders are ready to write off the brand? Really? OK, here's another data point: I've ridden these tires for about 30K over the last few years with only a couple of pinch flats. No failures, no blowouts, no problems. So I guess I should ignore the success I've had with them and dump them based on a single incident.
> 
> Sheesh...


Thread is quite real bro, you've been on here a couple years and you haven't seen the usual suspects go after each other under the guise of debating a topic? 

Same thing happens on most online forums unfortunately but not everyone is a genius like us


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## dmanthree (Aug 22, 2014)

BacDoc said:


> Thread is quite real bro, you've been on here a couple years and you haven't seen the usual suspects go after each other under the guise of debating a topic?
> 
> Same thing happens on most online forums unfortunately but not everyone is a genius like us


Sigh...

And I thought we were discussing tires.


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## terbennett (Apr 1, 2006)

I know the earlier models were rubbish in terms of durability of the sidewalls. My understanding is that the GP4000S IIs are supposed to be an improvement over the old ones and the sidewall failure issue had been resolved. My 13 year old son is running the GP4000S IIs 650c on his road bike. Should I be concerned for his safety or are these just remote instances? He loves them and says that he can tell the difference between these and his old tires. I swapped them without even telling him and while out on his first ride. he said, " Dad, something is weird about my tires. They feel really light and they are super comfortable. They've never felt like this before. These tires don't feel slippery in corners anymore." I told him it was because I switched them for new tires. He swears by them now. I would just hate to switch him to a different tire when I've finally found a decent 650c tire, and one that he actually likes.


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## dmanthree (Aug 22, 2014)

terbennett said:


> I know the earlier models were rubbish in terms of durability of the sidewalls. My understanding is that the GP4000S IIs are supposed to be an improvement over the old ones and the sidewall failure issue had been resolved. My 13 year old son is running the GP4000S IIs 650c on his road bike. Should I be concerned for his safety or are these just remote instances? He loves them and says that he can tell the difference between these and his old tires. I swapped them without even telling him and while out on his first ride. he said, " Dad, something is weird about my tires. They feel really light and they are super comfortable. They've never felt like this before. These tires don't feel slippery in corners anymore." I told him it was because I switched them for new tires. He swears by them now. I would just hate to switch him to a different tire when I've finally found a decent 650c tire, and one that he actually likes.


The "old" GP4000s is the same tire as the "II" version, only the cosmetics have changed. It's a safe tire. It's not a pure race tire, but an all-rounder with decent puncture protection, but not the equal, in terms of durability, of the GP 4 Season. I've been riding them for thousands of miles with no tire failures of any kind. Yes, the occasional pinch flat, but that's about it. Pay attention to the wear dimples, replace them when there's just a little bit of the dimple left, and you'll be fine. The paranoia surrounding these tires is totally unwarranted.


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## mfdemicco (Nov 8, 2002)

BruiserBob said:


> had the same failure. I feel lucky to be alive since the sidewall failed on a descent
> 
> View attachment 314035


This is what Continental says in their instructions: "Sharp-edged rim flanges of carbon rims can slit open the tyre side. This increases the risk of an accident with unforeseeable consequences."


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## mfdemicco (Nov 8, 2002)

defboob said:


> So i've got around 200 mi on these tires (700x25 on CAAD10) and things were great, was really enjoying them - when on today's ride, I was just finishing up 30+ miles and i started to hear a strange sound from my front tire. As i began to slow down and pull off to see what was up, the tire just went KA-POW and was finished - blew out from the side. See below for a picture of what it looks like. Somehow the wire bead blew out the side and went outside of the rim walls, very strange. Anyone ever have this happen to them? Defective tire? I don't get it. It was inflated to 90psi, i'm about 170lbs - and i've had a good bit of riding on them so far with no issues, including a century ride. Thank goodness it didn't happen earlier on the ride in a spot that could have been way more dangerous, i was right near my neighborhood where i was just finishing up, so i just had to do the walk of shame home. Just curious to hear any insight from others - as far as I can tell i had it installed correctly and had a good bit of hard miles without issue.


This type of failure can occur if you slide a tire lever along the bead. It can damage the bead.


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## thumper8888 (Apr 7, 2009)

terbennett said:


> I know the earlier models were rubbish in terms of durability of the sidewalls. My understanding is that the GP4000S IIs are supposed to be an improvement over the old ones and the sidewall failure issue had been resolved. My 13 year old son is running the GP4000S IIs 650c on his road bike. Should I be concerned for his safety or are these just remote instances? He loves them and says that he can tell the difference between these and his old tires. I swapped them without even telling him and while out on his first ride. he said, " Dad, something is weird about my tires. They feel really light and they are super comfortable. They've never felt like this before. These tires don't feel slippery in corners anymore." I told him it was because I switched them for new tires. He swears by them now. I would just hate to switch him to a different tire when I've finally found a decent 650c tire, and one that he actually likes.


There's no more reason to worry about these than any other top of the range performance tire from any manufacturer.
Years ago there was a run of them with a manufacturing problem, but it's just not a problem now and there are many, many more of these out in the field than just about anything else of its type. Just a couple of aberrations noted here.
Of course he feels he difference... GP4000s may be worth 5-10 percent of a young rider's FTP power over another manufacturer.
Right now, for fast training, fast group rides and racing, there is no better mix of durability, puncture resistance, aerodynamics and rolling resistance.
The data is out there from numerous places and there is enough of it to make it inarguable.
Now, you remove any one of those and another tire may be better, and people pick tires for different reasons. If you have a long gravel driveway, or regularly ride sections of gravel, def get something else. There may be a couple of tires more aero but likely not, that's not one of the things like puncture resistance that often creates a tradeoff with weight and rolling resistance.
Specialized tires probably will or already have caught up, but there's not enough data out there on anything except rolling resistance, where Specialized has an edge, but are less aero. There's also a sense that maybe they haven't caught up in puncture resistance and wear, but they have hired the right people to fix all that, so its probably a matter of time.
The wild card is tubeless... various manufacturers like Schwalbe are getting really, really close to delivering great road tubeless tire that will change the equation of the various tradeoffs some, especially if you run them with high quality sealant.
But for now, anyone wanting a high-performance clincher should, like many tire testers, consider the gp4000s2 the benchmark.


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## izza (Jul 25, 2012)

As Thumper says the tyres are a benchmark for high performance tyres. The only caveat I have to that is in relation to the OP's sidewall issues and my own problems with melted bead cover on an alpine trip. 

I am now not keen on them but respect others may choose them for their tread performance.


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## rooksmith (Jul 4, 2005)

I had one with the new Continental







Grand Prix 5000 Not as bad but WHY should we put up with this?


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## OldChipper (May 15, 2011)

upstateSC-rider said:


> Here come the conti-lovers saying that you hit a rock or installed it wrong or soaked the tire in hydrochloric acid, blah, blah. Anything but the truth which is way too many people have had problems with them, and this coming from a former conti-lover.
> Glad you kept it upright.


Well honestly, I have over 80,000 miles on GP4000S II and GP5000 Tires over the last 10 years or so and have NEVER had a sidewall blowout that wasn‘t a direct and immediate result of hitting a large or sharp rock (and even then I think I’ve had a grand total of 2), so there’s that. IME most people who have that problem over-inflate their tires. I’m 84kg-ish and run 90/95 front/rear.


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## tlg (May 11, 2011)

OldChipper said:


> Well honestly, I have over 80,000 miles on GP4000S II and GP5000 Tires over the last 10 years or so and have NEVER had a sidewall blowout that wasn‘t a direct and immediate result of hitting a large or sharp rock (and even then I think I’ve had a grand total of 2), so there’s that. IME most people who have that problem over-inflate their tires. I’m 84kg-ish and run 90/95 front/rear.


Ditto. GP4k was my main tire on all my bikes for years before switching to GP5k TL. Never once had a sidewall issue.


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## No Time Toulouse (Sep 7, 2016)

He's just an "angry consumer" with an axe to grind; he just keeps posting the same thing in multiple forums.


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## Oxtox (Aug 16, 2006)

yeah, had a couple of sidewall tears with the older 4KI tires and switched to other brands for a while...tried Michelins, Rubino Pros, Schwalbe ONEs...

those tires were ok, but simply didn't match the Conti 4KIIs for ride quality and durability.

have gone thru at least 6-7 pairs of the 4KIIs with no issues. have a set of the 5Ks on deck and imagine they'll be fine.


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