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So a friend of mine sent me this picture of a "blow out" that happened on his wife's car (some Infinity coupe). She said that it just happened all of a sudden with no warning.
She says she pulled over as soon as possible, but from that severe damage, it seems like something else must have happened.
What would cause the entire sidewall of the tire to disintegrate like that? I'm not sure, but these could be run flat tires since its a newer, nice car.
This tire was driven on long after the blowout
When there is sidewall separation from tread carcass like this it had to have been driven on longer than claimed.
When a tire suffers pressure loss and the car compresses what's left of the tire there's a fold along the sidewall that, if driven on, heats up due to the bending and associated friction.
Once the carcass gets hot enough the tread portion will separate from the sidewall, which is what happened here.
I don't know what actually punctured the tire but it's clearly been driven on for too long.
A word in defense of the driver
Sometimes a rear tire failure is not really evident and if you're driving in a straight line you may not know the rear tire is flat if you don't pay attention to such things. Granted, that's bad but, it's the way it is too.
Answer
Driven on long after pressure loss.
Open Question
Unable to determine root cause of pressure failure.
Why doesn't your friend believe his wife? The tire probably blew up when it hit a pothole or curb. She drove without noticing until it started to pull to the side. Probably a little while until she found a safe place to park.
What's so unbelievable about the above scenario? You and your friend should chill out and be happy that she is OK. Blow outs can kill you.
From the look of the rim, it seems it may have been in contact with something ... that something may have been a curb or two. If so, this could have weakened the side wall, which caused catastrophic failure. Given other factors, like if the tire was low on pressure and was continued to be driven on, then this to could have exacerbated the situation. Hot road/area conditions may be of some consequence as well.
Bottom line, while I'm sure this appeared to have happened spontaneously to your friend's wife, there were probably a plethora of other circumstances which have caused the tire to become a molten mass of rubber. Rather than allow your friend to beat his wife up (figuratively) over the blown tire, tell him to get it replaced and thank heaven there was no loss of life. Having a blow out like that at highway speeds leaves the driver with just about zero control. Looks like she did a good job of getting the vehicle to the side of the road without loss of life or limb. Have your friend congratulate her on her great control and get some brownie points for it.
I've had the wall separate like that after a blow-out, just in the time needed to stop. My impression is that the rim sliced it as it drove flat.
So, it doesn't take a "long time". Just going from freeway speed to stopping at the roadside is time and distance enough.
If you look at more than just the sidewall, you'll notice the tread shoulder is heavily worn. This tire is well beyond 3/32 and verging on bald in most of the tread pattern. There is slight cupping that indicates habitual under inflation by 3-6 pounds. Another factor is that it looks like a lower profile tire (though hard to tell for sure from this angle), which is affected by under inflation even more. There less sidewall support. In turn that causes more flexing and increased heat when under inflated. I bet if you were to ask the wife or the friend, how it felt while corning, they would use the word spongy as the tire slightly rolls side to side under load. They would, if checked, see lots of microcracks about 2" out from the rim on the other tires. They should replace all 4 tires.
Let's look at some other clues. They are in the Desert SouthWest where running bald is done more often because people stupidly think that tread is only for moisture control. I'm betting they have to drive several miles to reach a filling station and that the tires are well hot at that point.
To get a better understanding of the inflation, they should get a dial tire pressure gauge, spend a couple of extra bucks for the one that holds its pressure until released so they can write down the numbers. Then measure all 4 tires right around sunrise. Drive to the filling station and add extra air to each tire based on the cold pressure measured at/before sunrise. They may need to check on multiple days, based on how low the cold tires are. Also I'd be willing to put $5 on that they are slowly loosing air though the hammered sidewalls. Example: cold temp is 29, vehicle placard says 35 for that tire. that tire gets 6 lbs on top of what it reads at the station.
In answer to your other question, I don't think it was driven on long, but the tire is so hammered as a unit that once the sidewall failed it was a like a zipper ripping open all the way around the tire. You can see that by the jagged edges on the tear. There is splaying where the laminate separated but the edges are still crisp and there are thin fibers which would have been worn off if there was any appreciable distance on the rim. I bet the inside is beat up if not partially separatated as well?
Only thing I can think of is that the sidewall was destroyed by a curb at just the wrong height, or something similar. You would have to be fairly oblivious to not notice that the drivers side rear of the car was no longer on a tire, but rater on the sidewall. I would guess it was something faster, like a sewer drain lip, curb, something that dug into the sidewall and nothing else.
But it's really hard to tell what really happened as the damage hides the root cause pretty well. It could be that it was driven on for a long time after the blowout.
I once stopped to help a couple of fellow motorists who had that kind of damage to their tire. In their case they had a small object (like a screw) stuck in the tire. So it seems they had gotten a slow leak which caused the tire to depressurize until the walls of the tire gave out.
The rim looks fine from what I can see in the picture so I find no reason to believe that someone has driven on the rim for an extended period of time after the failure.
Hence my guess is small damage led to a leak that led to a rapid failure when the walls gave out.
I have had a similar experience of the rear off side tyre disintegrating on the highway. The car was mainly used for short distance city travel only. First noticed a vibration from the rear of the car and by the time got to the shoulder to check the tyre was heated up and shredded. Maybe about half a km. I guess even a few rotations with the edge of the rim digging into the soft rubber can cause it to separate. The other important thing is to check the manufacture date of the other tyres which is embossed on the side wall (maybe only on one side) It gives the week and year of manufacture. If more than 5 years better replace all as if it happens on the front it can be very dangerous due to loss of control.
