Tire Problems? Some Facts from a Tire Engineer

[tireman9]

I haven't been as active on Heartland as I would like but I have a dozen forums to monitor and of course my RVTireSafety.com blog, plus I do have other interests. But I felt I might help owners have a better understanding of tires and tire problems with this summary

First off there is a lot of confusion about tire failures. Incorrect terminology makes it harder or even impossible to properly diagnose the reason for a failure. I think you can understand that if you run over a screw or nail there is a good chance you will leak air which can ultimately lead to a Run Low Flex failure (most call this a Blowout). Any tire can get a puncture so blaming the tire is of no value.


You can also have a leaking valve or an actual failure of the valve body itself which again leads to air loss followed by Run Low Flex failure

You might have a detachment of the tread and/or belts from the body. In this cast the tire may even retain all its air. The cause for this can be excess heat or age has caused a loss in flexibility and strength of the belt rubber.

Finally there may have been a problem during manufacturing. In this case we usually see a batch (100 to 100,000) tires that might have a failure. Usually there is a recall.

Run Low Flex failures can be almost completely eliminated if you run a TPMS. While checking the air each morning is good thing to do, it does nothing to warn you that you have a leaking valve or a cut or puncture. It only takes a few miles at very low pressure to flex the sidewall to the point the body ply melts.
and and are examples of Run Low Flex failures

Here is what melted body cord can look like or

These conditions are physical proof the tire was run miles at significant underinglation and highway speed.


A Tread detachment results from weakening of the belt rubber. If the wrong rubber was used in manufacturing( defect) the tire would most likely fail at very low mileage. A much more likely cause is accelerated aging of the belt rubber. This occurs when the tire is overheated. The aging rate of rubber doubles with every 18F increase in temperature so parking with the tire in full sun and not under a white cover can accelerate the aging ( loss of strength) to 4 times as the test I wrote about in this post shows a 36F increase in tire temperature because of no cover.

Another cause of increased belt rubber temperature comes from higher speed and certainly increase heat comes from higher loading. These affects are additive.

Finally we need to remember that damage (aging) to the rubber is cumulative and cannot be reversed. Once you run your tire underinflated putting air back in the tire does not repair the damage already done. The heat/time affects are cumulative and every hour/day week spent at elevated temperature causes the belt rubber to loose its elasticity which can lead to tearing and ultimately to a belt/tread separation.

I have over 100 blog posts and I am sure there is a lot of information that you might find of value, so take a look if you have more questions.
I have my email posted on the blog under my picture and will answer questions. I do ask you provide the complete tire size information including Load Range and your tire loading will certainly help.

Roger

 

[brianharrison]

Thanks for the link Roger - good information on your blog.

Brian

 

[mattpopp]

Tireman,

When mine blew. The thread came off. Then the tire blew. I know this because the trailer felt like I ran over a small car and then it was follow by an loud explosion.

Trailer was less then a few months old with approx 1000 miles on it. I was about 40 or 50 miles from the house. Before leaving I had just checked the tires air pressure. This was a Cyclone but for the most part the trailer was empty with the exception of about 200 lbs worth of personal items in it.

Because of reading all of the horror stories before that happened I was terrified to drive over 60mph. Now that I have 17.5's with a tire rating well beyond what the trailer can handle and a speed rating of 75mph. I exploit that every chance I can get. It's a good feeling when you have a few ounces of confidence in your tires.

You can only assume that the trailer was delivered with proper tire inflation.

But one thing you have to assume. Is that people that have trailer tire failures caused by the end user. You would think they treat all of their tires the same. Including their TV and any other personal vehicles that they have. It seems that they would or could see the same possible failures across their personal fleet. That's in the aspect that they would report those tire failures as well.

If they don't and most cases of tire failures on this forum and any other Trailer based forum are only related to ST tires. The trend seems that ST tires are just poor quality tires. Not made to the same spec and quality as of passenger tires.

I guess my argument is why aren't we seeing several TV tire failures as well if we want to blame the end user for not properly caring/using his tires? Or blaming it on a road hazard. Because most of your conclusions are suggesting that most cases are caused by mis use. Just seems like there should be alot of TV tire failures as well if that is true.


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[Rodbuster]

Roger, thank you for taking the time to post that information.

Dick

 

[caissiel]

Tireman,

When mine blew. The thread came off. Then the tire blew. I know this because the trailer felt like I ran over a small car and then it was follow by an loud explosion.

Trailer was less then a few months old with approx 1000 miles on it. I was about 40 or 50 miles from the house. Before leaving I had just checked the tires air pressure. This was a Cyclone but for the most part the trailer was empty with the exception of about 200 lbs worth of personal items in it.

Because of reading all of the horror stories before that happened I was terrified to drive over 60mph. Now that I have 17.5's with a tire rating well beyond what the trailer can handle and a speed rating of 75mph. I exploit that every chance I can get. It's a good feeling when you have a few ounces of confidence in your tires.

You can only assume that the trailer was delivered with proper tire inflation.

But one thing you have to assume. Is that people that have trailer tire failures caused by the end user. You would think they treat all of their tires the same. Including their TV and any other personal vehicles that they have. It seems that they would or could see the same possible failures across their personal fleet. That's in the aspect that they would report those tire failures as well.

If they don't and most cases of tire failures on this forum and any other Trailer based forum are only related to ST tires. The trend seems that ST tires are just poor quality tires. Not made to the same spec and quality as of passenger tires.

I guess my argument is why aren't we seeing several TV tire failures as well if we want to blame the end user for not properly caring/using his tires? Or blaming it on a road hazard. Because most of your conclusions are suggesting that most cases are caused by mis use. Just seems like there should be alot of TV tire failures as well if that is true.


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I have many reasons to agree with your comments rather then the OP.
I have used overloaded and overiflated LT tires on my trailers for years without problem. While having replaced failing ST tires that were twice the cost and failed within 2 years. And they were either GY or Carlisle.

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[tireman9]

A couple things are very different between TT and "personal vehicles". 1. The TT was probably towed x hundred miles at y speed (time is money) from factory to dealer. Are you 100% certain the factory inflated the tires to the sidewall pressure when it left the factory and the guy being paid to deliver never exceeded 65 mph? maybe we can ask how many people confirmed they had the correct inflation when the left the dealer.
Second thing is that cars are delivered on trailers. I know tire inflation is set at the factory to spec as I have monitored tire inflation at a number of OE factories. Finally cars normally have 20% reserve laod or more while it is well documented that over 50% of TT have a tire overloaded.

 

[MCTalley]

When we left the Heartland National Rally in Goshen this summer, we headed west on I-90 to the Seattle area. We were passed by several trailers being delivered from Indiana to points west, typically running speeds from 70-75 (we always run 62-65, even though I have G-rated tires rated for 75). At least one was a toy hauler from a manufacturer we are all very familiar with.

 

[danemayer]

When you consider that most of the tires are rated at max 65 mph, and that they can't shed built-up heat that occurs at 75 mph, and that heat damage is cumulative, maybe it's not too surprising that we see lots of early-life tire failures.

I've also wondered how many trailers are towed nose-high or nose-low, putting excessive load on and possibly damaging one of the axles.

 

[mattpopp]

A couple things are very different between TT and "personal vehicles". 1. The TT was probably towed x hundred miles at y speed (time is money) from factory to dealer. Are you 100% certain the factory inflated the tires to the sidewall pressure when it left the factory and the guy being paid to deliver never exceeded 65 mph? maybe we can ask how many people confirmed they had the correct inflation when the left the dealer.
Second thing is that cars are delivered on trailers. I know tire inflation is set at the factory to spec as I have monitored tire inflation at a number of OE factories. Finally cars normally have 20% reserve laod or more while it is well documented that over 50% of TT have a tire overloaded.

You are relying on a bunch of "what if" scenarios to prove the user is at fault for ST failures.

At the end of the day if a ST tire was manufactured to the same specs as a LT (Passenger Tire) you would see a great reduction in tire failures. Probably at that point trailer tire failures will be as common as they are on your pickup.

So rather then trying to make people understand why they are at fault when a ST fails. Why not research and test using a LT tire as a trailer tire. The sell the idea to people why a LT tire is the right choice with a ton of data/research to back that fact.

Because it seems for every reason why a ST tire is the right choice for trailer tires it is also the exact reason why they are horrible for handling loads.


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[caissiel]

Well said and I totally agree.

My ST failures were only used by me. I to have seen delivered trailers zoom by me at excessive speeds. When I first checked my new trailer G Rated tires they were at 85 to 90 psi cold.
But delivered trailers are not usually loaded to the Max. And how many realty check tire pressures and temperature. Kicking tires and checking hub temperature is more like the norm.

 

[murry135]

I like what tireman9 has to say. An ounce of prevention is worth a lot. Many variables that we forget to take into consideration like the deliveries and the abuse prior to our ownership is a big concern. Unit leaves factory A-OK but is abused for several hundred miles and then we get it. Not every problem is visible so take into consideration ALL FACTORS when it comes to safety. Things will fail thats why we have Home Depot, Lowe's and home reapir experts.

 

[mattpopp]

I find it hard to believe that these tires result to premature failure due to possible mistreat from the factory delivery across serval state lines.

Bottom line, ST tires are junk that are made with very low standards. When they are used to close of their max rating they can't handle it. It's why you see so many failing on TH. Make any accuse blaming the end user or the delivery man.

I'll stick to my original argument. If the problem is the end user then why aren't they also complaining about the constant premature failures on their personal vehicles. Because they will treat their trailer tires the same as their vehicle's tires.


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[danemayer]

I think Progressive Insurance has a device that plugs into vehicle connectors to record driving patterns including mileage and speed. They use it for insurance purposes, but I wonder if it's inexpensive enough that RV manufacturers could by a few dozen to monitor what the transport drivers are doing. Just thinking out loud.

 

[dave10a]

I set my speed control to 62mph and enjoy the ride. My tires run about 50 deg above ambient depending on the sun location and run a little hotter when the sun is directly on them. My rear axle is out of alignment by 1inch which make the rear tire run 5-10 deg hotter while it is slightly feathering. I am not sure how alignment affects the tires other than high rate of wear.

 

[Gary521]

I find that Tireman9 has a lot of good and informative information. I will continue to read his stuff. However, I think that mattpopp is kinda on the right track too. There is something symptomatically wrong with the ST tires made in China. It may be inferior materials, inferior manufacturing methods or something else. Something is not right. Maybe from a design and engineering standpoint, ST tires are the thing to use. From a manufactured in China standpoint - forget it. A couple of years ago we had a huge problem with springs failing on Lippert suspensions from springs made in China. Was there abuse by the end user here? I think there is a pattern here that needs to be heeded. If you like playing Russian Roulette, keep using these tires.

 

[caissiel]

My ST tire problems started in 98 and solved in 2002 with cheap LT tires. At the time in 98 all heavy units had LTs. But on 5k axels they had ST D rating tires that were GY junk. A least on my unit.



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[Manzan]

Dave10a, I would think the tire scrubbing would take its toll on the bearings. When I had the bent axles the bearings as well as the tires got ruined but must have been bent a lot worse. Did major damage in just 3800 miles. My rig is a lot lighter but still had problems but all is good now. Tires run about 10° above ambient and a bit more in the sun.

 

[dave10a]

Dave10a, I would think the tire scrubbing would take its toll on the bearings. When I had the bent axles the bearings as well as the tires got ruined but must have been bent a lot worse. Did major damage in just 3800 miles. My rig is a lot lighter but still had problems but all is good now. Tires run about 10° above ambient and a bit more in the sun.

Not sure about the bearing wear. However, the tire temperature of 50 deg F above ambient is about right according to the Valor tire monitor company. That s tihe inside casing temperature and not the tread temperature. Racing tire get near 200 deg on the tread and aircraft tire get near the same. That's one reason, I believe, racing and air craft use nitrogen instead of normal air the small amount of oxygen in normal air can cause a fire (rapid oxidation) while nitrogen does not. Axel alignment turns out to be a bigger problem than I thought for RV trailers-- especially with some trailers having an uneven weight distribution because of slides and/or poor engineering/layout to please the layout demands of the public. Any tires is a big topic with a lot of bias out there. BTY I experimented with nitrogen and found it a waste of money for normal pickup and RV applications-- the effects turned out to be negligible as I would expect.

 

[mattpopp]

Race cars that demand absolute performance tend to use a high quality nitrogen (such as medical grade) because there is almost no moisture in it. Moisture expands due to heat causing air pressure to increase in those type of situation.

Otherwise I wouldn't run Nitrogen. Being that nitrogen is thinner then air you will find that nitrogen can leak in a tire where regular compressed air won't.

But my air compressor already produces 78.09% Nitrogen.

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[brianharrison]

Being that nitrogen is thinner then air you will find that nitrogen can leak in a tire where regular compressed air won't.

But my air compressor already produces 78.09% Nitrogen.

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This is incorrect. it is the O2 that "leaks" out - ie permeates the rubber. The O2 molecule is a bit smaller in size than N2. Do not confuse molecular weight with molecular size.

http://www.getnitrogen.org/pdf/graham.pdf