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Discussion Starter · #1 ·
Today I did a short ride to test out my new Reynolds DV46C wheels and Swisstop pads. On the 1.5 mile steep twisty descent near home I heard a faint rubbing noise from the front, in time with the wheel. After a moment I figured out that it only happend when the brake was on and I thought "oh no, that's not good". Before I could stop the tire blew out explosively. No problem getting to a safe stop and I managed to walk home.

But I'm concerned because I don't know why the tire blew. The brake pads are no where near the tire and the tire doesn't show any signs of being rubbed by a pad so that's out. One of the tire sidewalls looks like it seperated from the bead (pic below). It's like the bead pulled right out of the tire.

On the other side is a 1/2" cut (2nd pic). I don't remember running over anything that would have caused that, but it's possible that I did and didn't notice it.

The rim felt warm to the touch when I stopped, but not hot. I'm wondering if I damaged the bead area when I mounted the tire. These were the most difficult tires to mount (on these wheels that is) that I've had in 20 years.

Any ideas what happened?

View attachment 129127
View attachment 129126
 

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where was the rip in the tube?

On the blown-out-bead side, or the side with the smaller cut?
 

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"One of the tire sidewalls looks like it seperated from the bead (pic below). It's like the bead pulled right out of the tire."

That's what happened.

Once that happened, the tube was able to bulge out, and then blew.
 

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Discussion Starter · #4 ·
Not sure. When I looked at the tire before removing it, the blowout in the tube looked like it was under the blown out bead side. But when I line it up on the rim with no tire on it, it's on the cut side. Maybe I had the tube twisted inside the tire. I'm usually pretty careful about that but with the difficulty of mounting the tire it might have gotten twisted.
 

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Discussion Starter · #5 ·
That's what I think too, but what would cause that? Excess heat? It wasn't all that hot for an aluminum rim but I don't know if carbon is different. Damage while mounting? A bad tire?

The tire's a Michelin Pro2.
 

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Maybe it started with the cut, which could happen from hitting some road debris, without you being aware. The tube bulged through the cut, and the sound you heard was the tube bubble brushing the caliper when the brakes were applied. Then the bubble blew, and your high-speed stop on a totally-deflated tire did the rest of the damage, including the ripped-out bead.

That's the best theory I can come up with. I would inspect the rim carefully, but I'm sure you know that.
 

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same thing

Had the same thing happen a few years ago with a Conti Gatorskin. Just blew a hole in the sidewall, separting from the bead. Happened while still in the garage as I as inflating it. Chalked it up to just a bad tire.

I wondered at the time if there was a chance I damaged it when I installed, as it was a tight fit, as you mention. Don't know how I'd figure it out, though.
 

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Discussion Starter · #10 ·
edorwart said:
You may want to read what I posted at the end of this the thread below about my Reynolds Carbon Rims.
It looks like you have a different issue than I did. On yours the tire cut above the bead. On mine, the part of the tire that wraps around the bead seperated and the fibers of the bead pulled through the tire.

I'm pretty sure that I damaged the bead area when installing the tire. The tires were TIGHT and the most difficult to install that I've dealt with in 20 years of riding. Of course I could have damaged the bead on a sharp edge of the rim. I'll inspect the rims again.

Did lightly sanding the bead area of the rim fix your issue?

The more I think about my problem, the more certain I am that the bead failed first. The noise I heard was the loose tire hitting the brake arm when I braked. The cuts on the opposite side were from the loose tire getting pinched between the road and rim.
 
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