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  1. #1
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    GP4000SII Sidewall Blowout

    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 exacGP4000SII Sidewall Blowout-npw-tire-outside.jpgGP4000SII Sidewall Blowout-npw-tire-inside.jpgt 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?

  2. #2
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    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.
    use a torque wrench

  3. #3
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    do a forum search on 'sidewall'...

    there are some similar threads regarding Contis (and some other brands as well).

    ride em or don't...most users find them to be high-quality tires.
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  4. #4
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    Quote Originally Posted by MMsRepBike View Post
    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.
    ^This^. And post in the correct section, which would be...you guessed it...WHEELS&TIRES. General Cycling Discussion is NOT the place for every post.
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  5. #5
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    I came here thinking there was a Blowout Sale on tires.

  6. #6
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    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)

  7. #7
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    Quote Originally Posted by MMsRepBike View Post
    If you cannot manage to do that, you should switch to a different tire. Maybe the 4 seasons.
    4 Season sidewalls are no better than GP4000s, in my experience. I can't fault your advice about staying out of the gravel, though.

    Only other comment is that given the usual Conti failure mode, once I get even a small nick in a sidewall I write the tire off rather than try to eek more miles out of it. It's possible OP got a small cut a week or month ago and it picked this ride to let go.
    It's Mueller Time

  8. #8
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    I cut three of them in about 100 miles.
    I've never cut a Vittoria Pave or Corsa in 50,000 miles.

    Some say those 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.
    Last edited by Jay Strongbow; 1 Week Ago at 11:21 AM.

  9. #9
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    Quote Originally Posted by Jay Strongbow View Post
    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.

  10. #10
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    Quote Originally Posted by woodys737 View Post
    Not that it really matters but, for the masses, I've had the opposite experience.
    Google searching shows about 10x the number of hits for sidewall blowouts on contis compared to vittoria.

    I don't know the numbers of each ridden by cyclists, which would be needed to make a guestimate on probabilities. A WAGuesstimate of course.
    .
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  11. #11
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    Quote Originally Posted by QuiQuaeQuod View Post
    Google searching shows about 10x the number of hits for sidewall blowouts on contis compared to vittoria.

    I don't know the numbers of each ridden by cyclists, which would be needed to make a guestimate on probabilities. A WAGuesstimate of course.
    Yeah it's strange and freakin me out as I've had the opposite experience. 3 sets of wheels with these mounted. IMO they handle the heat really well and I do ride on messy fod ridden streets. Just ordered another set as I type...

    Another tire I tried and thought sucked (for flats but rolled better than anything) was the Specialized Turbo Cotton. People roll those all day and no problems. I gave mine away they sucked so bad. Maybe it's me.

  12. #12
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    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.
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  13. #13
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    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.
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  14. #14
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    Quote Originally Posted by woodys737 View Post
    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.
    We're talking about side wall cuts. Not natural wear or routine flat. Sounds like you are talking about wear and regular flats. No questions Vittoria corsa wears faster and probably flats easier.
    The difference being you have to throw out a tires with a side wall cut not regular flats and longevity is something you can choose to accept or not before buying.

  15. #15
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    Quote Originally Posted by Lombard View Post
    However, because the TPI is higher, the threads are thinner and therefore more fragile and more prone to punctures.
    I think it matters what those threads actually are not just the count. I've taken Vittoria Paves (320 TPI) though some nasty sharp rocks ect and never cut a side wall. Some of those 320 threads are kevlar and I think that matters.

  16. #16
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    Quote Originally Posted by Jay Strongbow View Post
    I think it matters what those threads actually are not just the count. I've taken Vittoria Paves (320 TPI) though some nasty sharp rocks ect and never cut a side wall. Some of those 320 threads are kevlar and I think that matters.
    Interesting. But are the Vittoria Paves as supple as the Conti GP4000S IIs?
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

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  17. #17
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    Quote Originally Posted by Lombard View Post
    Interesting. But are the Vittoria Paves as supple as the Conti GP4000S IIs?
    More so. in my opinion.

  18. #18
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    Quote Originally Posted by Jay Strongbow View Post
    More so. in my opinion.
    Hmmm. Maybe those are the ones I should try then. Noted. I love the puncture resistance of my Maxxis Re-Fuses, but wouldn't mind having something a little bit nicer riding.
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

    "Beware of geeks bearing formulas."
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    "Education is what you get when you read the fine print. Experience is what you get when you don't. -- Pete Seeger



  19. #19
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    Quote Originally Posted by Lombard View Post
    Hmmm. Maybe those are the ones I should try then. Noted. I love the puncture resistance of my Maxxis Re-Fuses, but wouldn't mind having something a little bit nicer riding.
    The are discontinued though you could probably still find some. But the new Corsa has the same casing so theoretically flat protection should be the same. They wear quick. Soft rubber and not a lot of it. Not sure how the new rubber with graphine they use now wears.

  20. #20
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    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. #21
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    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.

  22. #22
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    Some people just have better roads to ride on. The Conti sidewall issue is well documented. I don’t think our anecdotes are just noise.

  23. #23
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    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. #24
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    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.

  25. #25
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    Quote Originally Posted by npwhitman View Post
    IMHO these tires too susceptible to catastrophic failure for me and I will go back to a more durable tire.
    hey, whatever works for ya...

    I'll be rolling on Conti 4KIIs tomorrow with no worries whatsoever.
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