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Front tire blow-out
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Per what Brand of tires did you have, I’m going to watch the Video. Isn’t a TPS suppose to warn you of over pressure, When you set you baseline it’s like 20 percent over or under ?? My front is 13,700 and I run 100 PSI
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I would be extremely doubtful over pressure was the cause. The cold inflation pressures, if not exceeded compensate for heat and pressure build up.
The description of the tire completely disassembling itself from the wheel is a pretty good description of what happens with a zipper failure and those are almost 100% caused by running a tire at low pressure at some point in its life.
Unless Per bought those tires originally and knows their history he could have had a tire or tires a previous owner ran on low pressure.
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Jon, thanks for your kind comments in posting the “this video could save your life, yesterday.
Thanks, Jimmy for hot direct link
Over 300 hundred hits in one day after Per’s post there is interest again in this Michelin tire video.
Content and detail instructions have not changed even with age of that video.
AL
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Jon Said: “zipper failure and those are almost 100% caused by running a tire at low pressure at some point in its life., Re: “zipper failure and those are almost 100% caused by running a tire at low pressure at some point in its life.” A couple questions Jon.
1. What is considered low pressure on bus tires?
2. How many miles on low pressure before a long term tire problem would be expected on the tire degrading?
I understand there may not be an absolute but what are your thoughts? This is a great discussion as few things are more important than our tires!
Harry
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The tires were all Michelin XZA2s. They were 2012 vintage, and we bought the coach in December 2015. I run 120 psi steer, 100psi on drive and tag. By weight I could have gone 90 psi on the drive and tag, but I simply did not like the way the tires looked at 90psi.
No TPMS, I check the tires before any outing, but I may reconsider a TPMS!
All new shoes on the coach this morning. Prevost have XZA2s still, and I’m OK with those. Probably will make the next tire change at 6 years, though. I had them put the Goodyear 670 on the tag. Least critical, and I have heard people have had good service with Goodyears.
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If the tire casing was available a tire expert likely could do an examination of it and define the circumstance or circumstances that led up to the failure.
The reason I said zipper failure is in that type of catastrophic tire failure the entire sidewall of a tire opens almost instantly as if there were a zipper around the entire sidewall and it opened rapidly.
Think of taking a thin gauge strip of metal, kind of like a tape measure, and bending it back and forth over the same spot rapidly. We’ve all done something like that to break a strip of steel. As we constantly flex it, it gets warm, then hot then it breaks where it got warm and was flexed.
When a tire is under inflated that is what is happening to the steel belts in the sidewall of the tire. They are flexing too much, eventually starting to fail, getting warm, then hot, and then all of a sudden due to the tire pressure the belts start to let go. The ones that didn’t break initially fail because they couldn’t hold the tire together all by themselves.
A low pressure is defined as any pressure 20% or more lower than the pressure required based on the weight the tire carries. If a tire has been run at a low pressure it needs to be taken from service and inspected. If it has been damaged the evidence will be a dark spot around the inside of the sidewall on the inner tire liner. If you can see a dark spot on the outside of the tire you don’t need an inspection. The tire is junk, dangerous, and needs to be removed immediately.
If you find you have driven on low pressure and have to add air to the tire use extreme caution. That tire has the potential to literally explode. If you decide to add air yourself prior to an inspection, attach the tire chuck and stand well to the side while increasing pressure. If you hear any noises or snapping of what sounds like a steel wire breaking stop adding air immediately and get away from the tire.
We have had members describe damage and injuries due to tire failure. Per mentions how it took some of the coach skin off. Others have reported the tire also taking off skins from the coach, coach fenders and even a muffler. One member was airing an inner drive tire and when it exploded it blew the fender off the XLII, knocked him against a garage wall where he sustained serious injuries. Had it been the outside tire he could have been killed.
If you have low pressure on a drive tire, both tires on that side have been underinflated and both require inspection.
From Per’s post it is entirely possible the tire failure could have been the result of tire damage sustained prior to his ownership.
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For those wondering about tire temperatures, I took a picture of the Michelin tire rep’s slide presentation at the Prevost show a year ago. This is just informational so don’t shoot the messenger, but our tires can take a lot of heat.
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Per, no doubt a TPMS is helpful. But doing morning tire pressure checks and then during the day at rest areas shooting tire temps is a good alternative. Tires whose pressures are set according to weight carried are all going to run at similar temps, so while hot tire pressures are not reliable the temps are a good indicator all is well.
I have never seen tire temps greater than 150. It is most common during 80 to 85 degree days for me to see 135.
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Here’s an example of tire temps and pressures on a very hot day in the mountains out west last month.
The variation in temps and pressures while driving with the Pressure Pro and slight changes as the sensors report are normal.
Per – The one big plus for a TPMS is the alert should a tire start losing air due to a an unseen road road hazard such as a nail, bolt, screw, etc. Contact me if you’re interested in Pressure Pro.
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What I do not understand is how tire pressures are a constant, but temps are up.
It does show that tire temps on external sensor TPMS are based on an algorithm and are not an actual temperature reading. But they are accurate enough to show excessive values. Tom’s high temps are consistent with the values I have seen when using an IR temperature gun. The 160 reading is probably inaccurate on the high side, but still well below a dangerous temp.
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Frequent braking always pushes the inside tire temps up.
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That wasn’t my point. It is a law of physics that says as the temperature of the air goes up, so will its pressure within a sealed vessel.
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P*V = T
V = T/P, if V (volume) is constant then as T increases so will P … and vice versa.
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I’m surprised at such a small increase in pressure from pre trip to underway.
Mine increases much more than that……but, I don’t have the new sensors either.
My inside right rear drive is always hotter than others too.
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I went back and reviewed the video again. The one comment I have is that I’m pretty sure the drivers knew it was coming, and had a corresponding tight grip on the wheel. Unless you have a death grip on the wheel, the wheel will turn right out of your hands, and you need to be quick to regain control of the wheel. Pretty sure I did that at the same time I goosed the accelerator. I estimated I drifted a couple of feet into the left lane before I gained control, so be aware you need to be quick if this would happen to you, and I don’t wish that on my worst enemy. I’m not sure my heart rate is back to normal yet!
P.S. Progressive agreed to get a new wheel and tire, so I have proper wheel and a new Michelin om the tag as well. Will try to sell the wheel and tire back to Goodyear, if not, maybe as a emergency spare.
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