Blowout from heat?

High heat here, and much of the city without electricity.

Got no answer on phone, so I pedaled over to check on someone.

While there, my bike was on her front porch in the sun. The front rim
was new and so was the tire. (Replaced the day before.)

We heard a noise which I assumed was a .22 caliber firearm (that sort of
neighborhood).

When I tried to leave a few minutes later, the front was flat.
Examination revealed an inch-long tear in the sidewall and a similar
slit in the tube under it.

An 80 psi tire. Temperature only about 95°F Do tires blow out under
those conditions?

--
Wes Groleau

Why does everyone call it a “fanny pack" ?
When was the last time you saw one on a fanny?

On 7/1/2012 9:59 PM, Wes Groleau wrote:
High heat here, and much of the city without electricity.

Got no answer on phone, so I pedaled over to check on someone.

While there, my bike was on her front porch in the sun. The front rim
was new and so was the tire. (Replaced the day before.)

We heard a noise which I assumed was a .22 caliber firearm (that sort of
neighborhood).

When I tried to leave a few minutes later, the front was flat.
Examination revealed an inch-long tear in the sidewall and a similar
slit in the tube under it.

An 80 psi tire. Temperature only about 95°F Do tires blow out under
those conditions?


No, unless there was an already existing defect (or improper mounting)
aggravated by the heat.

--
Tºm Shermªn - 42.435731°N, 83.985007°W
Post Free or Die!

On Sun, 01 Jul 2012 22:59:47 -0400, Wes Groleau
wrote:

High heat here, and much of the city without electricity.

Got no answer on phone, so I pedaled over to check on someone.

While there, my bike was on her front porch in the sun. The front rim
was new and so was the tire. (Replaced the day before.)

We heard a noise which I assumed was a .22 caliber firearm (that sort of
neighborhood).

When I tried to leave a few minutes later, the front was flat.
Examination revealed an inch-long tear in the sidewall and a similar
slit in the tube under it.

An 80 psi tire. Temperature only about 95°F Do tires blow out under
those conditions?

No. If we assume an ideal gas, a constant volume of air, and 80 psi
tire pressure, the increase in pressure produced by raising the
temperature from 70F (294K) to 95F (308K) is only:
308K/294K * 80psi = 84psi

With a good tire, it's impossible to pump enough air into the tube to
blow out the sidewall. I've tried it and found that the tire bead
will pop off the rim first. With a tear or slit, I would look for
matching knife damage in both the tire and tube.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Jul 1, 10:59*pm, Wes Groleau wrote:
High heat here, and much of the city without electricity.

Got no answer on phone, so I pedaled over to check on someone.

While there, my bike was on her front porch in the sun. *The front rim
was new and so was the tire. *(Replaced the day before.)

We heard a noise which I assumed was a .22 caliber firearm (that sort of
neighborhood).

When I tried to leave a few minutes later, the front was flat.
Examination revealed an inch-long tear in the sidewall and a similar
slit in the tube under it.

An 80 psi tire. *Temperature only about 95°F * Do tires blow out under
those conditions?

I've had it happen twice. The most memorable was in the mid-1970s
when I lived in Georgia.

A bike shop friend had been telling me I needed to switch from
clinchers to tubulars. I kept on saying it wasn't worth the cost (I
was pretty broke), but he ultimately insisted I give his wheels a try
- light rims, Campy hubs, Clement del Seta silk tubulars.

So on a foggy Saturday morning I went out for a solo ride. The tires
and wheels felt nice, but I returned about noon, leaned the bike out
front in the hot sun, sat down to some cold drink and told my wife it
still wasn't worth the cost to me.

After maybe half an hour, there was a huge BANG and I went out to find
a hole, about 3/4" diameter, blown in the very top of the front tire,
right in the center of the tread. At that point, I was _sure_ it
wasn't worth the cost. (My friend let me split the cost of the tire
with him, since he'd been the one to insist I try it.)

The second incident was just a few years ago. My touring bike had new
Avocet Fastgrips on it, and was lying inside my parked car in the
sun. I came back to find a blowout due to a sidewall split.

It's never happened to me with a cheap tire. Go figure.

- Frank Krygowski

On Sun, 01 Jul 2012 20:45:44 -0700, Jeff Liebermann
wrote:

On Sun, 01 Jul 2012 22:59:47 -0400, Wes Groleau
wrote:

High heat here, and much of the city without electricity.

Got no answer on phone, so I pedaled over to check on someone.

While there, my bike was on her front porch in the sun. The front rim
was new and so was the tire. (Replaced the day before.)

We heard a noise which I assumed was a .22 caliber firearm (that sort of
neighborhood).

When I tried to leave a few minutes later, the front was flat.
Examination revealed an inch-long tear in the sidewall and a similar
slit in the tube under it.

An 80 psi tire. Temperature only about 95°F Do tires blow out under
those conditions?

No. If we assume an ideal gas, a constant volume of air, and 80 psi
tire pressure, the increase in pressure produced by raising the
temperature from 70F (294K) to 95F (308K) is only:
308K/294K * 80psi = 84psi

With a good tire, it's impossible to pump enough air into the tube to
blow out the sidewall. I've tried it and found that the tire bead
will pop off the rim first. With a tear or slit, I would look for
matching knife damage in both the tire and tube.


You may be right in theory, Jeff, but I have had several tires blow
the sidewalls from sitting in the sun, particularly on pavement. The
local temperature of the tire in direct sunlight, sitting on pavement
(asphalt or concrete) can quite easiy excede 150F on a 90F day, and
the heat softens the rubber of the tire as well. A properly seated
tire bead on a good rim can hold more pressure than a weakened
sidewall.
One weekend , I guess it was 2 years ago, we were having a garage sale
to get rid of some of the accumulated bicycles around my place and I
lost 3 tires in less than an hour. One was an older 20 inch fractional
tire, one was a newer 20 inch decimal tire, and one was a virtually
brand new 26 inch decimal (mountain bike ) tire.

The first one scared the heck out of me - and the next two were just
as bad. I let the pressure down on the rest of the bikes when the
second and third ones popped.

insolation

prob

1) vandals.....MO ?

2) uncured ur defective layup

a 'pop' sound LOUD is prob defective material, knifes et al ice pick....A WHAT ? releasing air more gradually

tires are 'handmade' off course being foot made or machine made....but whi knows in China....and everyone does it wrong OIAW.

wjat kinda tire was it ? did you say ?

new rims need examination, cleaning, poss deburring: check the underside of the area where the tire's bead grips.

prob take a better look at the tire next time, all times.

On Mon, 2 Jul 2012 02:22:40 -0700 (PDT), datakoll
wrote:

new rims need examination, cleaning, poss deburring: check the underside of the area where the tire's bead grips.

prob take a better look at the tire next time, all times.
In the case of mine, the tires had been on the rim for quite some
time. At least one was a Kenda, which had been on the bike for a
number of months.And no, there was no icepick or any other "attack"
involved.

On Mon, 02 Jul 2012 00:40:05 -0400, wrote:

On Sun, 01 Jul 2012 20:45:44 -0700, Jeff Liebermann
wrote:

On Sun, 01 Jul 2012 22:59:47 -0400, Wes Groleau
wrote:

Examination revealed an inch-long tear in the sidewall and a similar
slit in the tube under it.

With a good tire, it's impossible to pump enough air into the tube to
blow out the sidewall. I've tried it and found that the tire bead
will pop off the rim first. With a tear or slit, I would look for
matching knife damage in both the tire and tube.

You may be right in theory,

I just hate it when reality doesn't agree with my theory. Time to
change reality.

The
local temperature of the tire in direct sunlight, sitting on pavement
(asphalt or concrete) can quite easiy excede 150F on a 90F day, and
the heat softens the rubber of the tire as well.

Let's try the traditional frying an egg on the sidewalk trick, which
requires about 170F (352K) to fry.
352K / 294K * 80psi = 96psi
Ok, that's high enough to become worried but should not produce a blow
out failure, unless the tire was somehow defective or softened by the
heat.

I've seen a few blowouts, but they were caused by the tire coming off
the rim, exposing the inner tube.

http://sheldonbrown.com/brandt/blowouts.html
If there was an audible bang, then the tire was off the rim,
exposing the inner tube. However, the undamaged tire usually
remains on the rim because tires usually fall back into place
after exposing a tube. A tube cannot blow out inside the tire
with a bang, because a bang is caused by a sudden change in
volume, an expansion. Such an expansion is not possible
within a tire casing that is essentially air tight.

A properly seated
tire bead on a good rim can hold more pressure than a weakened
sidewall.

The OP notes that it was a new tire (and rim), which may have been
defective.

One weekend , I guess it was 2 years ago, we were having a garage sale
to get rid of some of the accumulated bicycles around my place and I
lost 3 tires in less than an hour. One was an older 20 inch fractional
tire, one was a newer 20 inch decimal tire, and one was a virtually
brand new 26 inch decimal (mountain bike ) tire.

The first one scared the heck out of me - and the next two were just
as bad. I let the pressure down on the rest of the bikes when the
second and third ones popped.

If it was that bad, my simple calculations must be in error or
something else was causing your tires to blow out. I'll assume that
the tires were not coming off the rim because there was a slit in the
tire sidewall. The increased tire pressure might have exposed a crack
in the tire sidewall, which then failed. However, that's unlikely on
3 different tires at the same time. The tread pattern would certainly
make a good stress riser, but the failures seem to be in the side
walls, not the tread.

Ok. I give up (for now)...



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Mon, 02 Jul 2012 07:33:46 -0700, Jeff Liebermann
wrote:

On Mon, 02 Jul 2012 00:40:05 -0400, wrote:

On Sun, 01 Jul 2012 20:45:44 -0700, Jeff Liebermann
wrote:

On Sun, 01 Jul 2012 22:59:47 -0400, Wes Groleau
wrote:

Examination revealed an inch-long tear in the sidewall and a similar
slit in the tube under it.

With a good tire, it's impossible to pump enough air into the tube to
blow out the sidewall. I've tried it and found that the tire bead
will pop off the rim first. With a tear or slit, I would look for
matching knife damage in both the tire and tube.

You may be right in theory,

I just hate it when reality doesn't agree with my theory. Time to
change reality.

The
local temperature of the tire in direct sunlight, sitting on pavement
(asphalt or concrete) can quite easiy excede 150F on a 90F day, and
the heat softens the rubber of the tire as well.

Let's try the traditional frying an egg on the sidewalk trick, which
requires about 170F (352K) to fry.
352K / 294K * 80psi = 96psi
Ok, that's high enough to become worried but should not produce a blow
out failure, unless the tire was somehow defective or softened by the
heat.

I've seen a few blowouts, but they were caused by the tire coming off
the rim, exposing the inner tube.

http://sheldonbrown.com/brandt/blowouts.html
If there was an audible bang, then the tire was off the rim,
exposing the inner tube. However, the undamaged tire usually
remains on the rim because tires usually fall back into place
after exposing a tube. A tube cannot blow out inside the tire
with a bang, because a bang is caused by a sudden change in
volume, an expansion. Such an expansion is not possible
within a tire casing that is essentially air tight.

A properly seated
tire bead on a good rim can hold more pressure than a weakened
sidewall.

The OP notes that it was a new tire (and rim), which may have been
defective.

One weekend , I guess it was 2 years ago, we were having a garage sale
to get rid of some of the accumulated bicycles around my place and I
lost 3 tires in less than an hour. One was an older 20 inch fractional
tire, one was a newer 20 inch decimal tire, and one was a virtually
brand new 26 inch decimal (mountain bike ) tire.

The first one scared the heck out of me - and the next two were just
as bad. I let the pressure down on the rest of the bikes when the
second and third ones popped.

If it was that bad, my simple calculations must be in error or
something else was causing your tires to blow out. I'll assume that
the tires were not coming off the rim because there was a slit in the
tire sidewall. The increased tire pressure might have exposed a crack
in the tire sidewall, which then failed. However, that's unlikely on
3 different tires at the same time. The tread pattern would certainly
make a good stress riser, but the failures seem to be in the side
walls, not the tread.

Ok. I give up (for now)...
Just aa a matter of interest, ONE of the three bluew the sidewall
right at the bead. The bead stayed on the rim, but the sidewall
separated from the bead. IIRC that one was an older tire. The new
Kenda popped about 1/3 of the way from the bead to the tread, and as
much as I respect the late Sheldon Brown's opinions and expertise, his
statement that a tire cannot cause a "bang" without the bead
separating from the rim is bogus. If a cord ruptures catastrophically
and the tube splits at the rubture, the volume of the bang can be
considerable.

Back when I was a young chap, about 45 years ago, more or less, a
couple friends and I decided to cycle from Elmira Ontario to New
Hamburg- a distance of about 40 Km one way. My bike was a then-ancient
single speed CCM 28 incher, my brother's an even older 28 inch
Cleveland with the double top bar - a tank- while both other friend's
had more recent 3 speed sturmey archer geared 3 speeds on 26 inch
fractional (not decimal) wheels. One of them had the skinny "racing"
type tire (smootish tread). As we were leaving Baden on our way to New
Hamburg (at about 35 Km or so into the trip) I broke off one of my
pedals, so we turned around to head for home. With a look of twine on
the remaining pedal to alow me to pull the ledal up as well as push it
down, we came down the old Rummelhart hill on Erb Street into
Waterloo through a police radar trap, at about 35 MPH. The cop told us
to be carefull - we were going too fast. As we headed out the old
Highway 85 through St Jacobs towards Elmira I was at the back of the
pack going down the incline past the Mennonite Church when the back
end of my friend Dave's bike jumped about 3 inches in the air with a
terrible "crack" and he swerved around a bit before coming to a stop
with a rip about 1 1/2 inches long in the sidewall. We walked the 4
bikes to the top of the hill, stashed them in a fence-lune and
hitch-hiked home. Dad went out with the van and picked up the bikes
after supper.