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GP4000SII Sidewall Blowout

23K views 170 replies 43 participants last post by  Lombard 
#1 ·
I recently suffered a sidewall blowout on my front tire during a descent and am lucky to be alive. In 40+ years of riding I have never had this happen before. I am 6'1", 240 lbs and ride 2,000 mi/yr. The tires were relatively new (500 miles) Continental Grand Prix 4000sII. I sent a picture to Continental and they said it was road hazard damage, not their fault, despite the fact that somebody else posted a picture with
the exac Finger Brown Synthetic rubber Black Tan
Brown
t same damage. I think it was either a design or manufacturing flaw. I really liked the way the tires rode but now I am scared to use them again. Is this a normal event and do I need to use a tire with stronger sidewalls?
 
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#2 ·
Yes and no.

Yes, it's road hazard damage. They are right.

Yes, the other person had the same thing happen to them as you did.

So have I, a few times, with the same tire.


Yes, this tire is known for having sidewall cuts/blowouts.

Yes, riding a different tire could help solve this problem for you.

No, you don't need to ride a different tire, you just need to pay attention better now.



What most likely happened, 99% of time when this happens, is you hit a piece of gravel.

Yup, that's all that happened, you hit a piece of gravel. A rock.

If you can manage to retrain yourself to pay better attention and avoid the rocks, you can keep riding this tire. If you cannot manage to do that, you should switch to a different tire. Maybe the 4 seasons.


I know how frustrating and scary it is, it's happened to me over 40mph on the front wheel more than once. I continue to ride this tire though, for me it's the best tire on the market. I have hyper diligence about gravel. I've never punctured any other way besides a sidewall blowout on these tires in over... I don't even know... over 30k miles at least.
 
#6 ·
That does appear to be a rock cut.

but at 240 lbs, I think you should get the toughest tire you can find that'll still fit your frame. Look into an "endurance" 28mm tire.

and when you descend, take the lane, don't go into the shoulders, that's where are the sharp rocks tend to be. Try to ride along the wheel tracks of cars, these are the cleanest real estates of asphalt you'll find on the road (yeah, there's a possiblity of an oil slick, but small possibility compared to sharp rocks on the shoulders)
 
#9 ·
I cut three of them in about 100 miles.
I've never cut a Vittoria Pave or Corsa in 50,000 miles.

Some say this tires suck because of the sidewalls. Others say it's just bad luck and it would happen with any tire. You can guess which way I feel based on my experience.
Not that it really matters but, for the masses, I've had the opposite experience. GP4000ii's have been amazing while I've had really bad luck with the Corsa. I don't have an exact amount of milage on my current set of tires but, it's thousands of miles. I'm totally guessing here maybe 3000-4000 miles. They are pretty square and I'm starting to think it's time...but, the proverbial rash of flats has not started yet.
 
#12 ·
I think the bottom line here is that while there are tires that do one thing well and there are tires that do many things so-so, there are no tires that do everything well.

Conti GP4000S IIs seem to be loved for their ride characteristics. They are supple, as are most Conti tires. Supple tires have a high thread count per inch (TPI). The higher the TPI, the more supple the tire. However, because the TPI is higher, the threads are thinner and therefore more fragile and more prone to punctures.

A lower TPI tire like the Maxxis Re-Fuse will be bombproof. The ride will be relatively rough, but running lower pressure can offset that to an extent.
 
#13 ·
You rode a tire and the cords failed, before you realized you had tire damage.
Do you inspect your tires regularly? If not, one should consider your choice of tire.
Personally I would not ride a tire that normal usage results in catastrophic failure.
 
#20 ·
After cutting a pair of 200mi GP4K S IIs in this manner on the same ride (one blowout, one I noticed the cut later at home,) I decided to stop riding the tires. There’s too much cracked pavement, small twigs, random pebbles in my area for tires with such thin sidewalls. Oddly the Vittoria Corsa G+ I tried never suffered sidewall cuts, but they had a tread life of about 1300mi on the roads here.

For me the solution was going tubeless basically. The naturally beefier casings on even the race tires plus being able to seal most punctures means I’ve only had two flats this year. One was a giant screw, so on me for not seeing it. The second was a defective IRC Formula Pro Tubeless tire.
 
#21 ·
I have been riding Conti GP4000IIs and 4 Seasons pretty much exclusively on my road bikes for the last three or four years.

Probably 25k miles all tolled, and I've never experienced a sidewall cut, and only a few (3 or 4?) flats.

I did slice a pair of them to the rim, but that was an unusual circumstance, were I rode over a sharp piece of metal that was laying across the road in a shaded area on a bright day, and I did not see it in time to bunny hop it. It would have sliced any tire to the rim. Fortunately, I didn't crash, and I was within walking distance of my house.

I've tried a few other tires (Schwalbe Pro One, Hutchinson Sector 28, Vittoria Corsa G+), but I keep coming back to Continentals.
 
#34 ·
Anecdotes are anecdotes - good or bad, correct?

I ride on good roads and bad roads, in the Pacific Northwest where it rains often, and the roads and shoulders are usually covered in various forms of debris most of the year. I'm also 6' 5" and 230lbs and average 10k miles a year. I would think I would be more prone to sidewall cuts than the average rider who is lighter, rides in places where the weather is better and the road conditions are not great.

The conti sidewall issue is pretty well document on google. Take it for what it's worth, but to me it does mean something when google returns a lot of negative posts on it, lol.

The Conti 4000 is one of, if not the most popular tire on the road. Just by sheer numbers there are going to be more anecdotal reports of failures than other tires.
 
#23 ·
To Review

Until this happened, I had never had a sidewall failure in over 40+ years of riding 2,000 mi/yr. I have ridden in the city, the country, and mostly in semi-rural Bucks/Hunterdon Counties. I can't say I inspected my tires the day of the blowout. This was a normal weeknight ride like hundreds of others, the only difference being the relatively new GP4000SII tires. I have been using other Continental tires and this was my first experience with this model. IMHO these tires too susceptible to catastrophic failure for me and I will go back to a more durable tire.
 
#24 ·
hmm I am just finishing up a full year on gp4ks2. I really love this tire. and .. I often ride on gravel, plus the bike lanes here are strewn with gravel.

however, I have a set of new Schwalbe Pro one tubeless I plan to start using soon. But I plan to do a 170km fondo first on the conti tires - on the very rough Tucson roads. Maybe I ought to swap now.
 
#26 ·
"These tires work fine in my limited experience" isn't really helpful to the many who do find GP4K sidewalls unacceptably thin or fragile.

https://www.instagram.com/p/BDOiPZhSOcW/?taken-by=dorkeugene

Look familiar? Happened on a post-rain ride with a couple of stray pebbles strewn on the road surface. If GP4Ks were true race-day-only tires like Corsa Speeds or some Veloflex tires, I'd chalk it up to picking the wrong horse for the course.
 
#27 ·
I finally gave up on conti GP series after riding them from the 3000 series up through the 4000-II.

On the rides I do, they tended to be flat magnets.

I changed over to vred tri-comp variants.

About a year later, I reduced the number of spare tubes I carry from 2 to 1, and I should probably check that one for dry rot.

The change in durability between the conti gp 4000 tires and the vred tri-comp is that dramatic.

Plus, the vreds compound, where the rubber meets the road, is a lot stickier in corners than the conti tires. Comparing the two, the contis were hard and slippery in corners compared to the corner-on-rails vred tri-comps.

Just my experience. I'll never buy another overpriced, overrated (imho) conti bike tire.

When I hear horror stories like sidewall blowouts (well documented) at 40 mph, but then the person says "I'll continue to ride conti GP 4000" tires, I just scratch my head.


BTW, I had similar experiences with crappy durability and performance with my conti summer ultra performance tires on my GTI. I couldn't believe the improvement when I dumped the contis for Michelin Super Sport PS2 summer ultra performance tires.

I think conti is riding a wave of brand loyalty that has been undeserved for about 5 - 10 years.
 
#28 ·
I changed over to vred tri-comp variants.

About a year later, I reduced the number of spare tubes I carry from 2 to 1, and I should probably check that one for dry rot.


When I hear horror stories like sidewall blowouts (well documented) at 40 mph, but then the person says "I'll continue to ride conti GP 4000" tires, I just scratch my head.
Another fan of the Vreds.

And, yeah, I don't understand the loyalty to a tire with a sidewall that the owner expects to have sidewall issues with.
 
#31 ·
The conti sidewall issue is pretty well document on google. Take it for what it's worth, but to me it does mean something when google returns a lot of negative posts on it, lol.

My personal experience with contis is that it's sidewall does seem to start to show sign of fraying way before the middle of the tire has come close to wearing out its life. I ride mountains every weekend so that means a lot of heavy braking on the front wheel, and it's almost always the case that I would have to ditch a conti due to sidewall starting to show sign of fraying. Not about to risk my life on a descend by trying to extend its life by a few more hundred miles.

To be fair, Michilen Pro 4 and Schwable also show sign of fraying too, but those take on a lot more mileage before so. I've find that the Vittoria Corsa don't show fraying at all, yet the Vittoria is a thinner tire! So something about the sidewall construction of Vittoria that make it last. Vittoria also handle like a boss in fast corner. I now use Vittoria for the front.
 
#32 ·
mmsrepbike, how can you tell it is road damage? What are the clues the tell you the difference? I’m not doubting you but I have no idea what to look for and am just asking so I learn something. I know if they were my tires I might remember hitting something as a clue?
 
#33 ·
Supple? Not sure I ever heard anybody call these "supple," unless you ride them at 80psi. In my experience, riding at 100-105 psi, these rode rather harshly.
Like the OP, I suffered catastrophic sidewall failure from fairly wimpy "road hazards" within 500 miles on different rides. Put a dollar-bill boot in there to limp home. The sidewalls lack a mesh material like, say, a dollar bill. Tear easily as a result. Nothing of the sort with 50k of riding PR3 and 4's, which corner better and exhibit a supple ride.
 
#35 ·
If the cuts were small, I’d be inclined to say it’s bad luck. If it wasn’t anecdotes from close friends with the exact same sidewall cuts, then again it might be bad luck. Unfortunately these are gaping tears in the sidewalls and they aren’t clean slashes... it’s actually the threads pulling apart. It also happens to enough people I know personally with just Conti tires and not other makes.
 
#39 ·
Anecdotal, operator error, supple, these are all terms used by those to defend the contis.
I've owned various Schwalbe, Michelin, Vittoria and Specialized tires. None of wich failed and some that were a much more supple ride than the Gp tires. My first set the rear side wall failed within a few hundred miles and the front failed around 500 mi. I would not buy again.
My new bike came with Conti 4 seasons that I think I'll leave on for this winter for base miles then change in the spring.
 
#55 ·
...And I doubt there are that many more Contis on the road than any other brand.
On BRAG this past summer, out of hundreds and hundreds of bikes seen the Conti 4000 was on what appeared to be almost 7 out of every 10.

The range and style of bikes were great, as were the riders and where they reside.

I've ridden most everything at one time or another and have my opinions but like it or not, it's undisputed, the GP 4000 is extremely popular and clearly the best selling tire going today.
 
#46 ·
To complicate matters about the Contis, here's what I've read about them. Here goes, and take it for what it's worth. Don't kill the messenger though!

big UK warehouse online sellers like Wiggle, Ribble, Probike Kit, Merlin, often will have deep discount on Contis. Maybe this is one reason why people keep coming back to them, however hesitant they might be. There were back and forth discussions that in the "user review" section of one of these site (I forget which one), and people were saying that these online sellers were selling really old tires, tires that have been in sitting in storage and showing signs of rotting. Others were saying that it's "B stock" tires, tires that came from batch that didn't pass QC test, but somehow made their ways to these online warehouses (knowingly or unknowingly to the warehouses even).

anyway personally, Contis to me suck for one major reason, they handle not as good as almost all other brands in the same price range. Contis have a few things going for them though:
1. they're on sale frequently
2. their middle section tread does last long, good if all you do is drone on flat road
3. good rolling resistance

but all these positives means jack to me if it's a poor handler, and a harsh ride. I'm thinking that the properties that give them good rolling resistance and longevity also necessarily make them poor handler and poor ride quality.
 
#57 ·
people were saying that these online sellers were selling really old tires, tires that have been in sitting in storage and showing signs of rotting. Others were saying that it's "B stock" tires, tires that came from batch that didn't pass QC test, but somehow made their ways to these online warehouses (knowingly or unknowingly to the warehouses even).
Given that Conti has updated the sidewall graphics pretty much every year, it would be painfully obvious is sellers were pushing "way-old" tires. And they would indeed have to be "way-old" and stored badly in order for "tire rot" to have begun.

The chances that large numbers of defective tires have somehow been spirited out of Conti's plants and made it into retail channels beggars the imagination.

Conti tires are very popular, and as a result there are more reports of tire failure about Conti tires than any other. What no one has ever presented is some factual information showing that they are somehow fragile and unreliable. Anecdotes are not data. The fact that there are large numbers of reports of people putting lots of miles on Conti tires with zero issues are just as persuasive as reports of fragile sidewalls.
 
#51 ·
There was also talk in past discussion about the 4K that maybe the SII version was better, improved for sidewall cuts. I use the 4KSII tires on the back, and over 15K miles, no issues. Won't use them on the front, though, as flats there are more serious than the rear. And I did have sidewall cuts on the old 4K tires, maybe once or twice, but none in maybe 3-4 years now on the SII.

I run Open Corsas on front. Both tires wear out about the same that way. No problems with the Corsas up front either, and I do agree they have thicker/better sidewalls than the 4KSII. Makes me feel better on 40 MPH descents.
I get the usual (occasional) flats from fine wires, glass, and so on, but usually in the center tread.

Also use the Rubino pro III on the rear, especially in winter, which has a LOT of tread to start, but wears about the same as the 4KSII for me. These are also pretty rugged tires, a little less supple than the Corsa or 4K, but cheaper, especially when they were being blown out to make the way for graphene versions.

My front and rear tires don't have to match.
 
#53 ·
was just reading some reviews on the BTDirect site...

saw some posts about Schwalbe ONEs having sidewall tears and bulges. oh noes...! another German tire maker that can't make decent products.

and fwiw, with ~250 reviews, the 5-star vs 1- or 2-star ratings for Conti 4Ks runs about 9:1.
 
#69 ·
another German tire maker that can't make decent products.
That seems a bit unfair. 4000Ss and Ones are racing tires. Rolling resistance and durability are two mutually-exclusive goals, and racing tires tend to pursue lower rolling resistance. Thin sidewalls are what give them the low rolling resistance. Putting more material in the sidewalls will make them more durable but less supple. If you expect your tires to withstand gravel and debris, get touring tires.
 
#59 ·
There could be other factors involved too - making problem more likely or less likely. Factors like tire pressure and wheel width. Perhaps narrow rims with large tires run at lower pressure will let more tire sidewall "hang out", making it easier to be cut than on a wide rim with less light bulb effect? Or maybe narrow rims and high pressures are the problem? I guess one could use a piece of sharp gravel and experiment on old tires.
 
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