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What the Hell caused this?????

I was running a large articulating forklift with grader tires on it and just finished unloading 8 lowboys with our steel building beams and parts on them (200’ x 700’) ish and one tire popped from bead to bead. It launched gravel over 150’ and blew out a truck window and scared the shit out of me. Sounded like a 12ga behind my ear.
 
the reason they run the huge tires is specifically so they can run low pressure
low pressure means low ground pressure, less compaction, less work when doing tillage (or less need for tillage)
That isn't quite how it works. Ground pressure is determined by the area of the tire in contact with the ground divided by the weight on the tire not solely the pressure in the tire. The lower pressure will increase the footprint to aid in that, but that is not the only factor.
 
second, those tires are not designed to handle high psi, so failure should be at a relative low psi. Or does not seem enough for that truck damage
Construction can aid in momentarily holding high pressure.

(I'm making this up as an example)

Let's compare pyro in a OTR tire vs rear tractor. The tractor tire is rated to cruise at 30psi, OTR runs 110psi. If you try to run the tractor tire at 110 it's eventually going to let go. BUT, sudden pressure spike during Pyro, maybe the OTR tire blows at 300psi but the tractor tire can hit 500-600 before letting go.
 
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Heat increases air pressure
While thats true, I cant see a tire getting hot enough to build that much pressure without either some outside influence or a chemical reaction like pyrolysis taking place.
 
Thankfully no one was in the area when it happened.

Just FYI. Aircraft have plugs that are installed into the wheel so when there is an over temp. of the wheel, the plug melts and releases the air inside the tire. That way the tire doesn't explode. I've heard the rush of air start after shutting the aircraft down. This happens, especially with hot brakes.
 
Too much either, lol

Watch his video and see much air can expand when it's heated, kinda like steam. This is actually why a diesel likes boost, the same thing happens when it fires, it transfers the heat to all the boost and takes advantage of all the enegry.

 
I've been present for four tractor trailer tires blowing in the past couple years - three tractors (drive wheels) and one trailer. Just sitting there - not even run that day. BOOM! Then we spend a few minutes going around trying to find which tire blew.

The combine is likely different as it was being operated.
 
Propane or ether used to seat the tires was left in there and heated up. That’s not simply overinflated tires.
It would take like 900 degrees to ignite propane. Gotta be just overflated, propane is irrelevant without a spark, right?

Just saw video above. Why and how do the temps go over 1,000???
 
I would have thought those had wet brakes, I guess not. Even still, I'm surprised they got that hot just from a short term usage. That blew on the ladder side, coulda been deadly.
If they are made like their s series replacement combines, which i highly suspect they do, they they do have wet brakes.

The only thing I have seen dry brakes on is the spreaders and sprayers. They have 2 calipers per each disc and the disc is about 2.5 to 3 ft in diameter.

I'd suspect tire damage aggravated by flexing via steering with brakes with a hopper full of grain (notice the extended auger.)

People just in a hurry. Nothing wrong with fixing that thing in the field where it died and driving the service truck to it. Its when you attempt to drive or move broken stuff that the really stupid shit happens.
 
It would take like 900 degrees to ignite propane. Gotta be just overflated, propane is irrelevant without a spark, right?

Just saw video above. Why and how do the temps go over 1,000???
Those front tires support most of the weight of a 30k lb machine, 12k lb cutting head, and another 15-25k lbs of grain, depending on hopper size.

They also function as the main suspension for the machine.
The air in those is constantly being rapidly compressed and expanded with a LOT of weight and force.
 
People just in a hurry. Nothing wrong with fixing that thing in the field where it died and driving the service truck to it. Its when you attempt to drive or move broken stuff that the really stupid shit happens.
I read it as they had multiple combines working in the field and moved it out of the way so that the other combine (or combines) could keep harvesting rather than having an area that couldn't be harvested until that combine was fixed.

Aaron Z
 
Just saw video above. Why and how do the temps go over 1,000???
It's a chemical reaction. The rubber essentially breaks down internally, and that releases heat, the more heat, the faster the breakdown of the rubber, which in turn creates more heat, which snowballs into more chemical breakdown.

The heat in turn causes the air to increase pressure until..... Boom.

At least that's how I understand it.

edit; pyralisis takes a catalyst to get it started. Typically something hot, and in direct contact with the rubber, such as welding on the wheel.

on the flip side of the coin, I've had a 10 ply light duty truck tire explode at or around 100 psi, and it sounded like a bomb going off... assumed it was from damage to the tire, or, old age, as truck was sitting at the time in my driveway.
 
It would take like 900 degrees to ignite propane. Gotta be just overflated, propane is irrelevant without a spark, right?

Just saw video above. Why and how do the temps go over 1,000???
Run away chemical reaction.
 
That isn't quite how it works. Ground pressure is determined by the area of the tire in contact with the ground divided by the weight on the tire not solely the pressure in the tire. The lower pressure will increase the footprint to aid in that, but that is not the only factor.
I suppose the carcass does hold quite a lot of weight when they're as thick as ag tires are
I just got suckered in by the simple math and engineering of "hey its a balloon pressed against the ground, of course its internal pressure is the ground pressure"
 
It doesn't take many P's to generate a big bang when you've got a lot of SI's

In order to get an over-pressure big enough to do that to a truck tens of feet away you need a lot of PSI at the source.

The truck has a ton more overall area than the tire. Even if you could magically make all the force on the tire translate to force on the truck you're still looking at a several to one reduction.
 
Why would multiple combines be running in a row?

If you need to get a combine out of the field for a repair like this, is it common to move the trailer move for move with it? Or to park the trailer back under the arm while doing the repair?

In the second picture, you can see over 20 ft to left of the combine and blown out tire. No truck to be seen. Maybe the guy sucks at gauging distance? maybe they moved the truck?

In the third picture, is that not the broke dick combine in the background of the truck? Again, maybe they moved the truck that is now filled with broken glass and deployed airbags?

Not to say it didn't happen and was a heat related issue. Just weird observations.. Would the bead come of the entire lip and and come back into the tire like that in the event of pyrolysis caused blowout? They use the cutting breaks constantly in combine derbys, never seen any of them blow out a front tire due to the heat. Not sure how far this kid went and why he would have been zig-zagging the whole way.
 
Why would multiple combines be running in a row?

If you need to get a combine out of the field for a repair like this, is it common to move the trailer move for move with it? Or to park the trailer back under the arm while doing the repair?

In the second picture, you can see over 20 ft to left of the combine and blown out tire. No truck to be seen. Maybe the guy sucks at gauging distance? maybe they moved the truck?

In the third picture, is that not the broke dick combine in the background of the truck? Again, maybe they moved the truck that is now filled with broken glass and deployed airbags?

Not to say it didn't happen and was a heat related issue. Just weird observations.. Would the bead come of the entire lip and and come back into the tire like that in the event of pyrolysis caused blowout? They use the cutting breaks constantly in combine derbys, never seen any of them blow out a front tire due to the heat. Not sure how far this kid went and why he would have been zig-zagging the whole way.
That’s my point about heat. Was he making a big wide arc and riding the brake for a mile? The explanations do not add up to pyrolysis started by brake heat, leading to blow out with so much force it caved in the side of a pickup with no carcass shrapnel
 
Why would multiple combines be running in a row?

If you need to get a combine out of the field for a repair like this, is it common to move the trailer move for move with it? Or to park the trailer back under the arm while doing the repair?

In the second picture, you can see over 20 ft to left of the combine and blown out tire. No truck to be seen. Maybe the guy sucks at gauging distance? maybe they moved the truck?

In the third picture, is that not the broke dick combine in the background of the truck? Again, maybe they moved the truck that is now filled with broken glass and deployed airbags?

Not to say it didn't happen and was a heat related issue. Just weird observations.. Would the bead come of the entire lip and and come back into the tire like that in the event of pyrolysis caused blowout? They use the cutting breaks constantly in combine derbys, never seen any of them blow out a front tire due to the heat. Not sure how far this kid went and why he would have been zig-zagging the whole way.
My bet would be that they pulled the combine near where the truck was parked (to use the compressor and/or tools to fix the tie rod), then moved the truck after the tire blew out to get the grain cart underneath the auger so they could unload the combine into the grain cart and make it easier to jack it up and change the tire.
On the bead, if I am seeing the picture correctly, it looks like the rim of the bead is there for where the "window" blew out of the sidewall.

No idea on why it happened to this one, but not to others.

Aaron Z
 
My bet would be that they pulled the combine near where the truck was parked (to use the compressor and/or tools to fix the tie rod), then moved the truck after the tire blew out to get the grain cart underneath the auger so they could unload the combine into the grain cart and make it easier to jack it up and change the tire.
Good point. :beer:
 
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