Weird exploding tires

Hello All

Hope it's alright to cross-post this to these two groups.

I have a very strange problem all a sudden on my old, trusty Fiorelli 10
speed (I have a 23 lb alternative machine, but this old, heavy bike just
feels right). I just repacked the hubs and replaced the tires and tubes.
Though I have old steel 27 1/4 rims, I have for decades used 27 1/8 100lb
tires for the higher pressure.

This has never been a problem until now. I mounted the front tire about a
week ago (set to 105 recommended pressure on Avenir Discovery Korean-made
tires). That went fine. Today, I mounted the rear tire and brought it up to
105. After about 5 minutes with the bike sitting by itself, the sidewall on
the rear one literally lifts out of the rim, blowing out the new tube. I
decide to try again. This time I take it up only to 90 lbs. About 10 minutes
later... the exact same thing! The tire lifts out of a section of the rim by
itself and the tube blows. I was down the block with a friend, and we could
hear it happen with the bike in my house and the door closed. Sounded like a
gun going off.

I can't figure out the cause. (I made extra sure that I did not catch any of
the tube under the sidewall when I mounted the tire). I'm 49 and have been
riding this bike since I was 17. I never saw a tire pop out of a rim like
this on its own. Tomorrow I'll mount an old tire and my last tube, just to
see what happens. But has anyone seen this before? The only possibilities I
can think of a

1) Using narrower 1 1/8 tires in 1 1/4 rims? (Never been a problem before
.... plus the front holds fine)
2) Some kind of defect in that rear tire
3) These are cheap tires with weak sidewalls or something. They were
inexpensive ($13). I've not used this brand before. But the front one hasn't
blown at full 105 lbs
4) Something suddenly wrong with the rim? It looks ok.

Any thoughts appreciated, especially if you've seen this before. I hate
blowing out tubes and REALLY don't want to blow out one of my ear drums.
Fortunately, in both cases so far, I was well away from the bike.

Thx


--
Regards,
Anthony Giorgianni

The return address for this post is fictitious. Please reply by posting back
to the newsgroup.

Thanks for posting that link .. and so quickly.

But nothing there seems to apply. There wasn't any heat. I didn't even get a
chance to try these new tires. And I used an old tube the second time. So it
couldn't have been the tube. But that page does make me wonder if there is a
defect in the bead of this new tire. Anyone seen that before , resulting in
a tire unseating itself?

--
Regards,
Anthony Giorgianni



From the Bicycle FAQ:

Blowouts and Sudden Flats:
http://www.faqs.org/faqs/bicycles-fa...section-2.html

On Fri, 20 Aug 2004 02:02:30 GMT, "Anthony Giorgianni"
wrote:

Hello All

Hope it's alright to cross-post this to these two groups.

I have a very strange problem all a sudden on my old, trusty Fiorelli 10
speed (I have a 23 lb alternative machine, but this old, heavy bike just
feels right). I just repacked the hubs and replaced the tires and tubes.
Though I have old steel 27 1/4 rims, I have for decades used 27 1/8 100lb
tires for the higher pressure.

This has never been a problem until now. I mounted the front tire about a
week ago (set to 105 recommended pressure on Avenir Discovery Korean-made
tires). That went fine. Today, I mounted the rear tire and brought it up to
105. After about 5 minutes with the bike sitting by itself, the sidewall on
the rear one literally lifts out of the rim, blowing out the new tube. I
decide to try again. This time I take it up only to 90 lbs. About 10 minutes
later... the exact same thing! The tire lifts out of a section of the rim by
itself and the tube blows. I was down the block with a friend, and we could
hear it happen with the bike in my house and the door closed. Sounded like a
gun going off.

I had a similar experience with a different brand and size of tire;
what I concluded was going on in that case was that the rim involved
was built with the assumption that the tires would have a reasonably
well-defined bead, and not have flat sides in the area which is in
contact with the rim walls. Flat-sided tires work perfectly well on a
rim that has a shallow flange (though getting the tires on can be a
challenge if they don't have a deeper recess in the center), but they
can produce the type of behavior you describe if the rim has a deep
flange that can allow one part of the tire to climb up as another
drops down into the recess.

Once I'd figured out what was going on, I made sure to use only tires
that had a protruding bead on that rim. No further trouble.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Anthony Giorgianni wrote:

Thanks for posting that link .. and so quickly.

But nothing there seems to apply. There wasn't any heat. I didn't even get a
chance to try these new tires. And I used an old tube the second time. So it
couldn't have been the tube. But that page does make me wonder if there is a
defect in the bead of this new tire. Anyone seen that before , resulting in
a tire unseating itself?



Yes, it happened to me with a very cheap 26 inch x 1.75 tire on my
mountain bike/commuter. The tire was brand new and just too poor
quality. Cost about $8 at a bike shop. I tossed the tire and bought a
rather nice Kenda gumwall tire - still inexpensive, but it's a fine
tire, with no problems after many miles of rough commuting.
The tire bead was too soft and would not stay on the rim with only 50
psi. I'm agreeing with your analysis and thinking the tire is the culprit.
When you manipulate the tire, does the bead feel too soft? Does it
appear to be poorly finished along the bead edges? If yes, then maybe
it's time to raise the bar a bit, if you know what I mean!

Best regards, Bernie

Anthony Giorgianni writes:

Blowouts and Sudden Flats:
http://www.faqs.org/faqs/bicycles-fa...section-2.html

Thanks for posting that link .. and so quickly.

But nothing there seems to apply. There wasn't any heat. I didn't
even get a chance to try these new tires. And I used an old tube the
second time. So it couldn't have been the tube. But that page does
make me wonder if there is a defect in the bead of this new
tire. Anyone seen that before , resulting in a tire unseating
itself?

I think you missed the part of the tube lying under the tire bead.
This is the most common blowoff problem, especially when no braking
heat is involved. If the tire bead is not properly seated in the
hook of the rim sidewall, it will come off.

Jobst Brandt

Anthony Giorgianni wrote:

Hello All

Hope it's alright to cross-post this to these two groups.

I have a very strange problem all a sudden on my old, trusty Fiorelli 10
speed (I have a 23 lb alternative machine, but this old, heavy bike just
feels right). I just repacked the hubs and replaced the tires and tubes.
Though I have old steel 27 1/4 rims, I have for decades used 27 1/8 100lb
tires for the higher pressure.

This has never been a problem until now. I mounted the front tire about a
week ago (set to 105 recommended pressure on Avenir Discovery Korean-made
tires). That went fine. Today, I mounted the rear tire and brought it up to
105. After about 5 minutes with the bike sitting by itself, the sidewall on
the rear one literally lifts out of the rim, blowing out the new tube. I
decide to try again. This time I take it up only to 90 lbs. About 10 minutes
later... the exact same thing! The tire lifts out of a section of the rim by
itself and the tube blows. I was down the block with a friend, and we could
hear it happen with the bike in my house and the door closed. Sounded like a
gun going off.

I can't figure out the cause. (I made extra sure that I did not catch any of
the tube under the sidewall when I mounted the tire). I'm 49 and have been
riding this bike since I was 17. I never saw a tire pop out of a rim like
this on its own. Tomorrow I'll mount an old tire and my last tube, just to
see what happens. But has anyone seen this before? The only possibilities I
can think of a

1) Using narrower 1 1/8 tires in 1 1/4 rims? (Never been a problem before
... plus the front holds fine)
2) Some kind of defect in that rear tire
3) These are cheap tires with weak sidewalls or something. They were
inexpensive ($13). I've not used this brand before. But the front one hasn't
blown at full 105 lbs
4) Something suddenly wrong with the rim? It looks ok.

Normally, either the tube was trapped under the bead (in which case it
may not actually pop off until you put more air in or the bike is ridden
a few miles), or the rim flanges are splayed from hitting a big hole.

But you shouldn't use 1 1/8 tyres if the rims really are 1 1/4 - this
will make them pop off at a lower than usual pressure. The optimum
tyre/rim width ratio is something like 1.5.

What great responses I'm getting here. Great ideas.

After reading your response, Bernie, I went over to compare the bead with
what's on my last tire (ISO Tech 2). It feels the same, BUT the sidewall on
these new ones seems tissue paper thin, especially where the light-colored
sidewall meets the black tread. I wonder if that's the problem, though I
wonder why the front one isn't slipping out.

I'm also wondering if Zog is right, that I shouldn't be using a narrower
tire. But I've never had problems with this before.


Regards,
Anthony Giorgianni

860-529-3308
Email:
Web page: www.giorgianni.homestead.com

"Bernie" wrote in message
...
Yes, it happened to me with a very cheap 26 inch x 1.75 tire on my
mountain bike/commuter. The tire was brand new and just too poor
quality. Cost about $8 at a bike shop. I tossed the tire and bought a
rather nice Kenda gumwall tire - still inexpensive, but it's a fine
tire, with no problems after many miles of rough commuting.
The tire bead was too soft and would not stay on the rim with only 50
psi. I'm agreeing with your analysis and thinking the tire is the
culprit.
When you manipulate the tire, does the bead feel too soft? Does it
appear to be poorly finished along the bead edges? If yes, then maybe
it's time to raise the bar a bit, if you know what I mean!

Best regards, Bernie

Thanks for the response Zog

Are you certain about that width issue???? I always thought it was fine to
use slightly different size widths. And this web site I just found seems to
agree ...
http://www.sheldonbrown.com/tire_sizing.html

I hate to go back to 1 1/4 (that IS what the rim says) because I can't find
any high pressure tires in that size. Also, I didn't even get a chance to
ride on this tire before it unmounted itself twice, so even if the size
isn't optimal, its seems unlikely that's the problem. But if you really
think it is, I guess I could go back to the 1/4s instead of the 1/8s :O(

As far as catching the tube under the bead, I'm always very careful with
that. When I first mount a tire, I always watch to see if the bead lifts any
when I start to put in air for the first time - a sure sign that tube is
caught under the bead. But after the tire unmounted itself the first time, I
was especially careful - blowing up the tube slightly and pinching the bead
slightly to double check that the tube wasn't caught anywhere.


--
Regards,
Anthony Giorgianni

The return address for this post is fictitious. Please reply by posting back
to the newsgroup.
"Zog The Undeniable" wrote in message
news:4125a37a.0@entanet...
Anthony Giorgianni wrote:

Hello All

Hope it's alright to cross-post this to these two groups.

I have a very strange problem all a sudden on my old, trusty Fiorelli
10http://www.sheldonbrown.com/tire_sizing.html
speed (I have a 23 lb alternative machine, but this old, heavy bike just
feels right). I just repacked the hubs and replaced the tires and tubes.
Though I have old steel 27 1/4 rims, I have for decades used 27 1/8
100lb
tires for the higher pressure.

This has never been a problem until now. I mounted the front tire about
a
week ago (set to 105 recommended pressure on Avenir Discovery
Korean-made
tires). That went fine. Today, I mounted the rear tire and brought it
up to
105. After about 5 minutes with the bike sitting by itself, the sidewall
on
the rear one literally lifts out of the rim, blowing out the new tube. I
decide to try again. This time I take it up only to 90 lbs. About 10
minutes
later... the exact same thing! The tire lifts out of a section of the
rim by
itself and the tube blows. I was down the block with a friend, and we
could
hear it happen with the bike in my house and the door closed. Sounded
like a
gun going off.

I can't figure out the cause. (I made extra sure that I did not catch
any of
the tube under the sidewall when I mounted the tire). I'm 49 and have
been
riding this bike since I was 17. I never saw a tire pop out of a rim
like
this on its own. Tomorrow I'll mount an old tire and my last tube, just
to
see what happens. But has anyone seen this before? The only
possibilities I
can think of a

1) Using narrower 1 1/8 tires in 1 1/4 rims? (Never been a problem
before
... plus the front holds fine)
2) Some kind of defect in that rear tire
3) These are cheap tires with weak sidewalls or something. They were
inexpensive ($13). I've not used this brand before. But the front one
hasn't
blown at full 105 lbs
4) Something suddenly wrong with the rim? It looks ok.

Normally, either the tube was trapped under the bead (in which case it
may not actually pop off until you put more air in or the bike is ridden
a few miles), or the rim flanges are splayed from hitting a big hole.

But you shouldn't use 1 1/8 tyres if the rims really are 1 1/4 - this
will make them pop off at a lower than usual pressure. The optimum
tyre/rim width ratio is something like 1.5.

"Anthony Giorgianni" wrote:

Today, I mounted the rear tire and brought it up to 105. After
about 5 minutes with the bike sitting by itself, the sidewall
on the rear one literally lifts out of the rim, blowing out
the new tube. I decide to try again. This time I take it up
only to 90 lbs. About 10 minutes later... the exact same
thing! The tire lifts out of a section of the rim by itself
and the tube blows.

Are you using hooked rims:
http://www.sheldonbrown.com/gloss_h.html#hook

I was first alerted to this problem when using Conti
TravelContact tyres. The sidewall of these states "Mount only
on hooked rims".

John

This reminds me of the time I tried installing a new tube and tire on
my first good wheel, not so long ago. Being quite inexperienced, I
pinched the tube between the tire and the rim. When I pumped it up to
about 105 psi, the tube exploded like a shotgun. Birds flew up around
me, dogs began barking, etc. Hard on the ears, too. It opened a
3-inch gash in the tube and I had to junk it. So I took the tire and
wheel into the bike shop at the local REI store and paid them to
install a tube and the tire. While I was browsing around the
merchandise waiting, I heard a similar loud BANG from the repair shop.
A minute later, the mechanic sheepishly came out to the floor to pick
up another tube for my wheel.
I felt much better about my own mistake.