RV Tire Safety: People still erroneously blame “defective” tires for “blowouts”

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By Roger Marble
Here is a post from July 22, 2012. The owners of this Airstream continue to use the word “defect” but also fail to identify the defect. I also see no signs of them running a TPMS.

“Blowout” – A real life experience

Picture 112

In a previous post I covered Run Low Flex Failure (RLOF) and how there were telltale signs or physical evidence. These, while taken individually, are just circumstantial in nature, but when taken as a whole they make a very strong case for the tire having been operated for a number of miles at very significant air loss. In this post, I want to walk you through the thought process of a forensic analysis of the evidence that is available and show how an opinion or conclusion is reached.

Picture 108

First, I need to tell you that I have not had the opportunity to personally inspect the subject tire, but there is a YouTube video and I will show you some shots from the video and tell you what I see in these shots.

Second, I cannot tell you about the individual as I have had only limited correspondence about this tire failure. But according to statements in the video they called it a “blowout,” said they had checked the air pressure in the morning and had only driven about 45 miles before the loss of air occurred.

Picture 057

So, let’s see what the pictures show. I have highlighted the area of interest in each picture. In picture #112 (above) we see in the yellow area signs that the interior of the tire was worn from abrasion on the inside of the tire under one side of the tread rubbing on the inside of the tire above the wheel. This occurs at 0 psi but takes more than a half-mile that it takes to come to a stop to wear this much.

Also the tire must still be in one piece such that the tread can uniformly contact the lower interior of the tire, so the wear occurred before the tread part of this tire broke away. In the red area we can see a few dark holes where the body cord has melted and shrunk back into the tire structure. This occurs when the body cord exceeds 390° F. To put this temp in perspective, properly loaded and inflated tires may get to 160° F and ultra high speed tires such as seen at the Indianapolis 500 may see 200° to 210° but rubber starts to come apart at just a little more than that.

Picture 426

In picture 108 (above) is another view of the same location of melted body cord. If the cord had simply failed due to high pressure, the cord would be frayed. Also note the nice circumferential line the failure took. More on that later.

Picture 121

Moving on to picture 057 (above), note the areas circled in red. An alternate view is seen at the arrow in picture 426 (above). Now, if we compare the loss of the ridge that is easily seen in picture 121, what this means is that the upper sidewall was in contact with the road surface for a number of miles and the outer edge of the sidewall “Scuff Guard” raised rib has been completely worn down. What we do not see is the lettering of the “Scuff Guard” worn away, so we know that the wear was not due to the trailer being repeatedly parked against a curb.

+++++++++

Now, I am sure some are wondering how I can tell the difference between running a tire at 5 psi vs. 0 psi. Well, here are some shots from an experiment I ran a few years ago.

This first picture (above) shows the wear of the upper sidewall that occurred in only 3.9 miles while the tire had a minimum of 5 psi cold inflation. This is a bit like the wear on the RV tire sidewall.

The next picture (above) is of the interior of the same tire. You can see the nice circumferential crease/crack that has formed. This tire did not generate enough heat to melt the body cord as I was driving at less than 10 mph for the 3.9 mile test. That crease is at the location up the sidewall similar to where we see the circumferential failure in the “blowout.” Note there is no contact between the inside of the tread and the inside of the tire above the wheel as seen in the RV tire.

Here are some examples that I use as reference pictures to help me understand the root cause of a tire failure.

These pictures show melted (fused) body cord, broken body cord and the holes sometimes left when the cord heats up and shrinks as it melts.

I hope this helps you see how easy it is to be mistaken when you think the failure is because of a defective tire when in fact the evidence shows the tire lost air, the RV continued down the road at normal highway speed, and after a few miles the tire “blew out.”

The only way to have some warning and to protect yourself against this all-too-often type of failure is to have a TPMS – which will warn you as soon as the tire loses 10% of its air.

Bottom line: I do not think this tire was “possibly defective” or a “crap tire.” It did not “fall apart for no apparent reason.” It came apart because it lost its air and the operator did not know until too late.

Read more from Roger Marble on his blog at RVtiresafety.net or on RVtravel.com.

 ##RVT976m

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Gary Broughton
4 months ago

Had 2 flats on my trailers in 45 years.
I don’t buy cheap Chinese or cut rate tires. I check my tires for air and flaws, maybe not daily but often. I have seen people turn corners dragging across curbs and driving thru holes and debris.
I’ve had 2 friend who have had several tire problems, even losing tires off the rim and one lost the rim off the axle.
It’s your trailer, check your tires.

Really
4 months ago

Roger:
I always enjoy your articles and since SAFETY is my NO. 1 thing in RVing, it makes me wonder why so many RVers will NOT invest in a TPMS (Tire Pressure Monitoring System)

We pay allot of money for our RIGS, why not invest in a TPMS for under $500???

Have a good day!

Kenny
4 months ago
Reply to  Really

I did invest in a TPMS system and after MANY trips with sensors going bad and false alarms going off for no reason and the warning that was real happened the second I heard thr tire blow I got tired of it and took them off. And yes they were set up properly as I had plenty of conversations with the company. By the way when the side of our rv got tore up by the time the sensor went off it was to late. These were tire minders.

billh42
4 months ago
Reply to  Kenny

I have had similar problems with my TPMS. I ended up sitting by the side of the road with a blown tire and after I called my road service provider the Tire Minder suddenly told me the tire had no air. Duh? I have also noticed that in urban areas with lots of RF interference there can be many false alerts. I also see at least one or two LOS alerts per trip. (I have the amplifier installed). Mine is at least five years old. Maybe the new ones are better?. Oh, and one other thing. The temp readout is not the tire or the wheel, it’s the temp of the valve stem. Could be a big difference. Also, every time I pull into a rest area and as the the tires cool and the pressure drops more false alerts. it’s better than nothing I guess but not by much.

Roger Marble
4 months ago
Reply to  billh42

I can’t address the delayed alert. have you run a TPM test as I outlined in my Blog? https://www.rvtiresafety.net/2019/05/have-you-tested-your-tpms.html

LOS may be low battery related.
I have written about the temperature warning. Metal conducts heat so the metal stem is going to be similar to the wheel which is similar to the hub & brakes. Your false alerts suggest your initial warning levels might need to be reviewed. See this blog post https://www.rvtiresafety.net/2017/08/how-i-program-my-tpms.html

Larry
4 months ago

Thank you for that very interesting and informative article.