TromboneAl

I had a 700 x 26C tire that I'd used for a while -- this one:



I put it on the rim of my wife's bike. The rim is labeled 700C.

When I pumped it up to 110, I noticed that the bead was coming off the rim. I assumed that I hadn't seated things, so I deflated, and redid it. Pumped it up to the recommended 115. While I was putting it on the bike, I heard a little rubbery squeaky noise, followed by BAM! Right in my ear -- could someone get the phone?

Why did that happen?

rhenning

The side wall has a cut in it just to the right of the word Sport. Side wall was damaged before you put it on your wife's bike, possibly while you were riding it or during the time it was off the bike. Your wife is not worth new tires. Mine is. Roger

HillRider

How old is your wife's bike? More correctly how old are the wheels? If it has the older "straight sidewall" rims, no tire will stay on above about 85-90 psi.

If it has newer "hook bead" rims, the probability is you had some of the tube caught between the tire's bead and the rims sidewall and it pushed the tire off the rim as you inflated it. It's a relatively common mistake. You should do a complete inspection of the tire/ rim interface to be sure the tube is completely within the tire before you inflate any newly installed tire.

Al1943

What HillRider said and the same can happen if even a very small part of the tube is caught between the tire's bead and the bottom of the rim, doesn't have to be the sidewall of the rim.

Al

DannoXYZ 

That's not a cut on the sidewall. It's just some clear plastic covering the decal that's coming off.

A blow-out from a cut-sidewall will expand that cut into a giant frayed star-shape hole, but the bead will not come off the rim. In TromboneAl's case, the tyre is perfectly fine after the blow-out, but the tube shoud have a massive gaping star-shaped hole due to it squeezing out from between the tyre and rim.

The ONLY reason a bead will come off the rim is due to a pinched tube that's stuck between the tyre and the rim (99.99% of the time this happens). After mounting a tyre, let the air out and pull it sideways to inspect the gap between the sidewall and rim. No tube should be showing. Move around the tyre systematically and pull the tyre sideways and inspect the entire circumference. Then do the other side of the tyre. No tube should be showing anywhere. Only then should you pump up the tyre.

Berre

I had the same problem with old "straight walled" rims; when inflated above 80psi the bead did not hold. Bought new (hooked) rims and built new wheels. Problem solved. Now I can inflate up to 110 psi. You really need that high pressure. Riding at lower pressure causes "snake bite" flats.

TromboneAl

Thanks for the help.

It's an 87 Centurion Ironman Dave Scott. I got it new, so I don't know about the wheels -- the one in front, which has one of the above tires on it now, is different.

The outer edge of the rim does hook around. I'll post pictures soon.

TromboneAl

I'll try putting it on again today, and will check carefully.

Here are the pictures of the wheel and rim with the tire that is currently on.

dobber

Wow. THe depth and breadth of your knowledge is truly underwhelming.

operator

...

Your tube was caught between the bead and the tire. Solution is to squeeze the tire all the way around to check for this once the tire/tube is mounted on the rim.

Failure to do this will lead to explosions.

TromboneAl

I guess you are right. I put the tire on today, checking very carefully, and it seems OK. Thanks for the help.