Continental GP 4000s Blowout

mitten reloaded · Joined: 27 Jun 2008 Posts: 330

So I had a sidewall blowout on my front Conti GP 4000s today on Toys Hill. Luckily I had just started the descent so made it to the side of the road safely. This is the 2nd side blowout I've had on a GP 4000 but otherwise have ridden Conti for years without incident.

Checking back, I bought them in Summer 2016. I wouldn't say they've had a huge amount of use & the wear indicators still have a fair amount of depth. I normally ride the winter bike with 4Seasons at this time of year so they really only get 3/4 of a year's use.

I have contacted Conti, more for their information, rather than for refund or complaint purposes, but I would be interested to know if:
- anyone has experienced anything similar with Contis ?
- is 2.5 years an excessive time to expect tyres to last ?

As an aside, both times I've fervently thanked whoever first thought of carrying a spare piece of old trye to make a 'boot' Smile

mattsurf · Joined: 28 Sep 2016 Posts: 852 Location: Zug, Switzerland

Was the bike sitting on a flat front tyre over the winter? if so this could have damaged the sidewall

Chrace · Joined: 28 Apr 2010 Posts: 2910 Location: Eating a Yorkie

Yup. I crashed.

I put it down to having done a major emergency braking exercise a few minutes before and possibly overheated the tyres in the process (alloy rim brakes). But I'm really not so sure.

Same as you I have ridden GP4000S and SII for years without incident but this one (SII) gave in with a complete failure in a sharp turn. Tyre rolled off the rim completely and I ended up turning on the wheel rim itself, which obviously then went sliding out under me.

I investigated a fair bit since it's what I can only call a catastrophic failure and I really can't afford that. Searching for "gp4000s sidewall" in Google quickly resolves with "gp4000s sidewall blowout" as autocomplete which is alarming. But searching for a variety of other tyres gives similar results and I couldn't pin it down.

The GP4000S is light due to less rubber in the sidewalls which would normally be ok but I got scared and changed to Continental Grand Prix (exact name) afterwards which is a heavier tyre but with double the sidewall thickness.

I've since then, about 2 years later, gone back to GP4000SII and had no problems since. And recently I have switched to disc brakes which hopefully removes the overheating problem - IF that was ever the problem. I hope it was.

My old comment can be found here.
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GrahamO · Posted: Mon Mar 11, 2019 2:18 pm Post subject:

Might be a thought but do you get the sidewall 'thread' coming off the rims on occasion ?

I recall I was always having threads stripping off from near the bead area and it would often wrap around the axle, and I notived the tyres then became a bit 'loose'.

Looking at your photo it looks as if the sidewall has lost something and I wondered if it was these supporting threads ?
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Andy916 · Joined: 08 Oct 2011 Posts: 712 Location: Cambridge

Is that the bead we can see in the second photo, or is that a sidewall split with the bead still seated? Had you recently fitted it to the wheel in place of your winter tyre?

I've known similar once, with a different tyre, when I managed to pinch the inner tube between rim and bead. It blew a short while later, damaging the tyre sidewall and taking a few cm of bead away from the rim.
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mitten reloaded · Joined: 27 Jun 2008 Posts: 330

Thanks for the advice. Photo is bit unclear - the bead was still seated, it's the sidewall that blew. The tyre had been on for a while so no pinching AFAIK & I don't recall seeing any threads stripping out prior to this. I did wonder about braking, although I had only just started the descent ( the 1st steep pitch on south side for those who know it) so I'm not sure about the effects of heat build up.

The other tyre that blew was the rear on a flat road so no consistency there either. I used to change my commuting tyres at the start of every winter so should maybe do the same the other way round.
I'll put it down to bad luck & just be grateful I wasn't 100yds further down at 30mph Smile

p.s. have just bought a new Canyon with discs so 50% of the possibilities should hopefully be eliminated Cool

Tony Stark · Joined: 26 Apr 2007 Posts: 2486 Location: Milton Keynes

MTBing is all about tyre inserts at the moment - I wonder how long before they make it to the road market.

dsm · Joined: 06 Sep 2011 Posts: 14 Location: catlow

had one blow out in 10 years on gp4000 i use 4 season in winter.if the wheel in the top picture is still attached to the bike then the tyre is on the wrong way.there is a rotational arrow on the sidewall

stenard · Joined: 04 Sep 2013 Posts: 2063

Jorgan · Posted: Thu Mar 14, 2019 4:15 pm Post subject:

Chrace · Joined: 28 Apr 2010 Posts: 2910 Location: Eating a Yorkie

There is a directional arrow on them but I'd question how much it matters. There is likely a small grip difference in corners but I've never seen anything mentioned about "internal thread layup" or similar that would affect the tyre if you brake on it the wrong way.

That said, I've always put them on the right way and had a blowout all the same.
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mitten reloaded · Joined: 27 Jun 2008 Posts: 330

GrahamO · Posted: Tue Apr 02, 2019 10:59 am Post subject:

Well I knew I shouldnt have commented on this thread as it was like talking about p*nctures.

The side wall on my front GP4000 just went ...... and looks somewhat like the OP's.

On further inspection, the side wall looks 'tired' (no pun intended) as if over the years its flexed to the point of becoming thin and weak. The wall separated from the bead slightly and that was enough to rub the brake block, heat up the tube and blow it. When the tyre was flat, it was a pain to find it.

Fortunately my emergency bit of tyre got me home but it wasnt the time to find out that my Co2 inflator won't fit to my valve extenders so the minipump it was to get what little I could into the tyre.

On to the next thread - how to use CO2 cartridges on extenders ....
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GrahamO · Posted: Tue Apr 02, 2019 5:02 pm Post subject:

The hole looks small but when the tyre is inflated is bulges along the rim line quite a bit, and you can see its well inside thr rim wall so not caused by a hard object hitting the side of the tyre wall.
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Whisk · Joined: 09 Jun 2005 Posts: 8739 Location: London