armstrong101

Hi folks

Has this happened to anyone before?

I left my bike in my caravan. At the end of the day, I take it out. I notice the rear tire is not completely mounted on the rim and there was no air in the tire/tube. So one tire sidewall was still entirely in the rim, but the other - had a 25 cm length of its sidewall outside the rim, as though the tire was being mounted, and the last step (sticking in the last bit) hadn't been done yet. The tube was blown, and on the rim there was some of that white talc dust on the rim where the tube blew.

I had ridden that morning and the tires were pumped to 100 PSI. There was no problem with the front tire as I released some air after the ride to remove it from the frame for storage in my van (they are 25c and they need to have air released to fit through the brake pads). The rear wheel wasn't removed and hence air pressure was left alone.

Hot day yesterday. I figure what happened was the air in the tube expanded - must have caused a balloon effect - ballooned itself outwards from a sidewall area, and eventually expanded until it created a hole, and "burst" (although the tube itself didn't burst like a balloon - it has a small perforation/opening).

Anyways - has this happened to anyone else before? Lesson learned. On a hot day, release air from your tires if you leave your bike in your car.

armstrong101

f/u question. At what PSI would a tube have to go to, in order to "open itself" from the tire and burst out the side like that? I'm wondering now if the sidewall of the tire I had is compromised. It did seem "stretched" at the point where it was outside the rim. Probably doesn't help that it was probably 60 deg celsius or whatever, inside the car. The PSI of the tire is rated to 120 (gatorskin).

thumpism 

I've been in there with one when it happened, and it was larger than a bike tube. Windows rolled up, it's an experience.

Then there was the time I was moving across country and had my Batavus wired to the ceiling ribs of my old panel truck with coat hangers. Eventually, a sewup sidewall wore through with that flatting sound we all loved in the '70s.

Spoonrobot 

Well, it's a continental tire so we can almost be positive it was a defective rim bead.

This is in jest but this is grounded in truth as well. https://www.bikeforums.net/road-cycli...en-happen.html

Darth Lefty 

Tire and rim models? Wire bead or folding? I'm curious.

Bikerider007

I vote tire defect if you could find no rim damage near hole that might cause that with a little expansion.

Trueblood

^ This. And the rims, hooked or not vs tire pressure rating for the tire?

Darth Lefty 

Consider that 60C is about 13% hotter than 22C on the absolute scale, and therefore making only 13% more pressure. Possibly less if the tire volume expands due to pressure or thermal expansion of the materials. Also consider that tires are vulcanized at something like 180C. Signs point to defect or damage.

corrado33

If we assume that air is an ideal gas, (bad assumption, but I'll allow it.) If the tire and air inside the tire reached 60C, then the pressure in the tube was ~200 PSI. Assuming you filled them up at 30 C. (Also assuming volume doesn't change, which it probably does, so probably a bit less than 200 PSI)

steelbikeguy

it's been a very long time since Chem 101, so I'm assuming that we're using PV=nRT. My rusty memory is telling me that the temperature uses degrees Kelvin, which would mean that the change in temperature would be roughly from 300K to 330K, producing a 10% pressure increase. .. ... ... right? (I'm really not sure)

I do think that the heating in the automotive greenhouse is the likely culprit. Many years ago, I saw the results of a can of soda sitting in a car, under the large hatchback glass, heating up enough to burst the aluminum can and act as a rocket, ending up in the front passenger seat and empty. Very remarkable! Fortunately, it was a diet soda, so it didn't leave sticky syrup all over the car's interior.


Steve in Peoria

NYMXer

I'm more along the lines of tube failure rather than tire failure. I think the tube couldn't handle the psi and once it ruptured, the tire sidewall broke the bead.
Look at it this way, if it was tire failure, the tube would still hold air? Just throwing it out there, not talking as a know it all.

corrado33

Crap, you're right, I'm an idiot.

armstrong101

I'll go home and get some answers and hopefully some photos for you all tomorrow.

Regarding the pressure, you would calculate it using Kelvin (not celsius), so it's far closer to a 10% increase than a 100% increase, going from 30 to 60 (although in my example, I'm guessing it's going from 20 to maybe 65? How hot does the inside of a car get on a hot day?)

D1andonlyDman

You've confused Celsius with Kelvin. The gas laws all assume temperature in Kelvin. I's closer to a 10% increase in pressure due to thermal expansion. Frankly, not as much as if you were riding on hot asphalt in the summer. I vote for defective tire and/or installation. BTW, to the OP, you're much better off that it blew in the car, than if it blew on a high speed turn.

steelbikeguy

that's okay... we are all idiots some of the time.

It would be fun to get a grant to study the basic issue of tires blowing due to heat, though.
Is it due to the beads stretching when warm?
Maybe the rubber gets soft and slides easier, making it easier to pop the bead off the rim?

Or maybe it's just those tires that were halfway to having the beads pop off the rim anyway? I've had tires that fit loosely and were prone to popping off if they weren't seated exactly equally around the rim.


Steve in Peoria

p.s. "PV = nRT" is one of the few things I remember from Chem 101, and it does come in handy now and then. Money well spent!

Darth Lefty 

Once upon a time when I had a black car and worked in the desert, my Starbucks frappucino cup shrank. In the process it did not leak. I'd have taken a photo but the employer was still figuring out their flip-phone camera policy. The same car over the first summer melted all the bits of glue holding its interior together.

RobbieTunes

It gets hot in those cars. I handled a couple of claims wherein a Bic lighter on a seat simply overheated, the car caught fire and burned the car on each side of it. I doubted it was possible, but the C&O investigator thought it might have been a prism effect via the lighter's case.

Slash5

I'd say a failure of some sort or possibly a prism effect as RobbieTunes says. I looked into this a while ago and I found that at least from what I could find on the Internet it's extremely unlikely - pressure increase should be fairly minimal.

Andy_K 

I haven't had it happen in a car, but I have had a tire explode in the middle of the night. I went down to the garage to see who got shot. It took me a while to figure out it was my tire. I had changed the tube earlier that evening. My best guess is that when I inflated the tire the bead wasn't entirely seated but was close enough that it took a while to work its way loose enough to blow. I didn't have related problems with the tire or rim before or after the incident, so whatever happened I'm certain it was user error.

Dave Cutter

A tire popped while I was in my garage... a short time after a ride. It "popped"... I heard the swish... and the tire went flat.

repechage

In the early 80's Mercedes would not sell the 500sec to the USA, a family member worked for a guy who brought one in grey market, black over black. San Fernando valley heat. Much of the interior plastic warped, the formulation used in Germany was not the same for the USA product. The car company would not warranty it, the cheapest route was to export the car back and warranty it in the homeland.
My guess was the interior temp reached 220+ degrees F.
For the ABS plastic to "flow", probably not enough acrylic -that will start to slump at 247 degrees F.
My guess though in this case that a very small amount of the tube was pinched between the bead and rim, ok under normal pressure, not happy when the system was heated up.

plonz 

I think Chrysler has a recall on the Caravans for excessive cabin temperatures when left in direct sunlight

Seriously, not uncommon to have a tire blow when left still in direct sunlight. Just happened to my buddy last weekend. I remember having a tandem tire blow just sitting on the rack on a really hot day. It was a self sealing tube and it blew that gunk everywhere.

tarwheel 

I haven't had a tire tube explode in my car due to heat, but I know quite a few other cyclists who have had this happen. If I need to leave a bike in my car all day in the sun, I'll let some air out of the tires. That should prevent the problem.

On a related note, I used to ride with a big guy who ran Vredestein 23 mm tires on his bike, pumped up to about 140-150 PSI. Vreds have very high pressure ratings, but I personally think it's crazy to run tires at that pressure. It also crazy for such a big guy to be running 23s. Anyway, I went on two consecutive rides with him in which one of his tires blew out about 40 miles into each ride. Both days started out with cool temperatures and warmed up significantly during the ride. After the second blowout, we convinced our friend that the flats were due to the air expanding in his over-inflated tires as the temperatures warmed up. I am certain that was the cause.

DiabloScott

Factors affecting blowouts:
You can estimate the importance of each factor, presented here in no particular order.


High initial pressure
Increase in pressure due to heat
Hot rim expansion and softening
Hot tire expansion and softening
Hot tire/rim interface effect
Size of tire and rim
Damaged tire bead
Damaged rim
Improper tire mounting

10 Wheels

Caravans do that.

When there is..Improper tire mounting