anyone has seen this before (tire bedding failing) ?

[dorin]

hi there,

yesterday for the first time i got a faulty tire (continental gp4000 II), the tire is about 6months old, ~5'000km, the wear mark still has plenty space available.
i did a long descent about 5 hrs before the tire "blew", ironically it did blew in the last 50km of the route where is nice and flat...

just wondering does anyone what can cause somethinkg like this, or is all down to usage / faulty product ?

[2lo8]

I've seen it before, but usually on pretty old cheap tires. I'm not exactly sure what causes it. Riding on flat tires, overinflated tires, or being left outside to dry rot might contribute, as I've normally seen this sort of failure on old or beat up bikes.

What pressure are you running at? the tread looks very flat for 5000km

[dorin]

Used to keep the rear at 7.5 bar (108 psi) for the last month was at 7 bar (99psi). Still the max allowed is 8.5 bar (125 psi).
The bike was always stored indoors, hence the thing that confuses me....

[Js2]

I had a similar blow out too, but diagonal instead of along the round path. Tons of tread left on the tire, noticed a bulge but lucky for me it blew out once I came to a stop.
Ran it on Zipp 303 NSW at 80 psi front 25mm
The GP4000 II were not even a year old...

Currently using the Vittoria Corsa Open G+

[jlok]

Have seen too many GP4000S/S2 failure, and I got one bulge at sidewall... great inexpensive tire, but have to accept that the construction is not the top.

[Calnago]

Sharp edges along the bead of some carbon clinchers can easily cause that and is a common warning. Continental and Veloflex are amongst the manufacturers who specifically state this. For example, Vision carbon rims and Veloflex clinchers are not a good combo. You don’t say what rims you are using but it’s something to keep in mind.

[dorin]

I put a picture instead Zipp 303 NSW, I still ride the combination fair 5’000km till this failure...

Sharp edges along the bead of some carbon clinchers can easily cause that and is a common warning. Continental and Veloflex are amongst the manufacturers who specifically state this. For example, Vision carbon rims and Veloflex clinchers are not a good combo. You don’t say what rims you are using but it’s something to keep in mind.

[sungod]

I put a picture instead Zipp 303 NSW, I still ride the combination fair 5’000km till this failure...

there's no set time/distance for a sharp edge to cause sufficient damage to lead to failure, batch variation in rim, tyres, other factors, or just bad luck, but cf clincher rims can certainly do this

fwiw this thread is also about carcass failure, it looks very much like cut by the rim, with zipp wheels...
https://weightweenies.starbike.com/foru ... 3&t=152486

[spdntrxi]

Have seen too many GP4000S/S2 failure, and I got one bulge at sidewall... great inexpensive tire, but have to accept that the construction is not the top.

This.. I've seen it on other brands but 90% it's always the Gp4000S/S2

[Shrike]

I had that last year. Posted a thread here about it. Low miles on the tyre.

In the end we couldn't work it out, though thinking was revolving around a sharp carbon rim being to blame, though hasn't happened since on that same rim and couldn't really find a rough bit on the rim.

Definitely quite strange.

Edit: to be clear it was on these 4000sII's.

[dvq]

Had this happen on a set of IRC tires for me, caused a flat, haven't tried any of their other tires. Has never happened to me again before/after.

[bm0p700f]

What rim dvq IRC use the Shimano standard for there tyre design and use there rims for testing. Campagnolo 2 way fit is the same, Mavic UST is so close that it's the same and kinlin is somewhere in between so that's the same too.

Rims that deviate from this standard can have bead hook radiuses that are too sharp or simply the wrong shape ( enve ses3,4 for example). Such rims may result in tyre failure.

It's not the tyres fault but rims made to a that will do standard. Also some alloy rims have sharp bead hooks. It not just carbon rims.

[dorin]

Could it be the rim (only)? I still managed to get 5’000km on the tires, I wouldn’t complain not having any flats and knowing I must replace the tires every 5k km...

[bm0p700f]

Next time though it might happen sooner though.

[dorin]

there are so many Zipps out there and carbon clinchers, if carbon rims are the culprit shouldn’t the net be flooded by examples like this?