Claims of "defective" tires causing "Blowouts" continue to be posted on YouTube

 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

In the previous post, I covered Run Low Flex Failure, RLOF, and how there were telltale signs or physical evidence that while each taken individually are just circumstantial in nature but when taking as a whole 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.

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.

So lets see what the pictures show. I have highlighted the area of interest in each picture. In pic #112 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 the half mile 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 an just a little more than that.


In pic 108 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.


 Moving on to picture 057 note the areas circled in red. An alternate view is seen at the arrow in pic 426. Now if we compare the loss of the ridge that is easily seen in pic 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 myself a few years ago.


  This first picture here on the left shows the wear of the upper sidewall that occurred in only 3.9 mi 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 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.

If you look at some of the examples shown in the previous post you will note that many show the same nice circumferential failure line.

Here are some examples that I use as ref pictures to help me understand the Root Cause of a tire failure.

Here are pictures of melted 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 till too late.  

 

##RVT976

Was your "Blowout" caused by parking at Quartzsite two years ago?

This is a bit of a continuation on the topic of "tire Dressing" from last week's post.

I do wonder how many that complain of sidewall cracking or less than desirable tire durability makes the effort to protect their tires from the heat and UV degradation from direct sun exposure.

While there might be some benefit and shielding from applying such as "Dressing" or "Shine" or other "stuff" to the tire sidewall for UV shielding. No dressing will protect a tire from the accelerated aging process due to being "baked" by the sun's heat.

There is no standard SPF for tire dressings as there is for sun-tan lotion, It would not be that difficult to measure the level of UV shielding by measuring the UV going through some clear plastic sheeting and then applying the tire dressing to the sheeting and measuring the level of reduction if any in UV rays.

In many cases, the rubbing of the tire sidewall when applying a dressing can remove the special anti-oxidants and UV protection provided by the chemicals the tire companies use in all tires.

All rubber, natural or synthetic, loses strength and gets stiff over time. The rate of degradation is also temperature-dependent with the rate effectively doubling with each increase of 18° F. As I have shown in my blog on the use of tire covers sunlight can easily accelerate the rubber degradation by 4 times with 8 times not unreasonable in Southern states. This loss of strength and flexibility can eventually lead to a belt separation, which many sometimes call a "blowout". Maybe that unexplained "blowout" in June was brought about by the eight months of direct sun exposure in Quartzsite, AZ, over the last two winters.

I have confirmed, with temperature measurements, the significant temperature drop with the use of white vinyl covers on Class-B, Class-C and RV Trailer sizes, and the use of a flat mesh "Tire Shades" on Class-A motorhomes. I would recommend against the use of black or dark color solid vinyl covers as they would act more like an oven by both transferring the sun's heat to the tire and preventing cooling air circulation around the tire.

##RVT948

Contain tire Blowout?

Every few months someone posts a question on one of the numerous RV Forums I monitor, asking if it is possible to prevent the damage done to the RV when a tire fails and has a belt separation or comes apart from a sidewall Run Low Flex failure.

 I have previously written on the idea of trying to "contain" tire failure on my blog but for those that missed the information here is a summary and links for more details.

In the tire industry, we have test drums surrounded by steel grating which weighs 6 to 10# per square foot so don't forget you would need a substantial structure to support a 200# - 500# "shield over each tire position. This extra weight would also significantly decrease the amount of "stuff" you can pack into your RV.
 IMO having worked around tire test labs, an effective "shield" on an RV is unlikely to work. I feel that prevention is a much better approach.

To better understand the problem I suggest you review the following.

1. Read this post.

2. This post shows the kind of forces we are talking about.

3. Check out the safety cage around this tire test machine.

4. Buy, program and test a TPMS

5. Every 2,000 miles or annually (whichever comes first) do a "Free Spin" inspection of trailer tires.


Prevention is much better than and less expensive than trying to protect your wheel wells.

I bleed off the high air pressure so I don't exceed the "Max Pressure"

The above statement or a variation of it seems to be made about once a week on one or another of the various RV forums I frequently review. It appears that many people incorrectly believe that exceeding the 'Max Pressure" number molded on the tire sidewall is going to result in tire failure and explosion.
It may help to let people know about some of the testings that tires undergo during the development phase.

First some background. The "Max Inflation" statement on your tire sidewall really is the inflation associated with the Maximum Load capacity. If you actually read your tire sidewall you will see that is what it says. So the number of PSI is really the minimum needed to support the stated load. It is important to understand that we are always talking about the "cold" inflation and not the inflation of a tire that is running down the highway or has been in direct sunlight or driven on in the prior couple of hours. "Cold" inflation does not mean the tire needs to be refrigerated but it means the tire is at the prevailing Ambient temperature.

With the introduction of aftermarket TPMS that report both tire pressure and the temperature of the sensor, people are now being exposed to numbers, they have no experience with. They see tire pressure rising as they drive down the highway. Some may see a 10% rise in pressure from the pressure they set their tires to just a half-hour earlier. Others may see a 20% or even a 25% increase in pressure and for some, this increase was a cause for concern. Not because they had any working knowledge of tire operating temperature or pressure but simply because the pressure was higher than they expected. A few people have decided that they need to bleed down the high pressure because they thought the pressure number of the tire sidewall was the max it should ever see.  Of course, the action of bleeding down the hot pressure was exactly the wrong thing to do as that meant that the tire would no longer be operating at the pressures expected by the tire engineer when they originally designed and tested the tire specification.

Obviously, this raises the question of how much pressure a tire can tolerate before the owner should be concerned. Well, I am going to give you some numbers but these are only examples. I cannot speak for every tire companies process of specifications but if we start with a few guidelines I think you can get comfortable and hopefully, you will believe that tire design engineers do have a reasonable idea of what they are doing.

First off we are only going to discuss regular production street tires that have passed DOT testing. The numbers I will use would basically be seen on new tires. I cannot advise on a tire's capability after it has been damaged or run for many thousands of miles. Damaged tires can fail when re-inflated as seen in THIS video. Heavy truck multi-piece rims MUST be inflated in a safety cage. If you suffered a puncture and drove any distance with the tire underinflated you may have permanently damaged the body cords which is why you should always tell the tire service person you drove on the under-inflated tire so they know to use a cage or other restraining safety equipment. Age and miles can reduce the strength of any tire but we do consider this degradation when approving a design. Another consideration is the availability of high-pressure air. Most home compressors or those that supply air to hoses made available to consumers have an upper limit of about 150 psi so we don't expect any consumer to have access to or to use industrial air pressure which can be 400 psi or even special inflation units as used on aircraft tires.

Basically many tires are tested to 300 to 400% of their rated inflation or above 200 psi whichever is lower. I had a number of tires that could contain over 300 psi when new but if they had been damaged the same tire might fail at less than 200psi but I also never, in my 40 years saw a tire fail from normal pressure increase and I was involved in the testing and evaluation of thousands of tires.

The BOTTOM LINE is Please do not bleed down your hot inflation pressure. You should ONLY set and adjust inflation when the tire is cool and at Ambient temperature. Doing otherwise MAY result in you having a failure days or weeks later because you were running lower pressure than what was needed for the tire load you were applying.

Two front tire "Blowouts" in one day

There was a thread started by the owner of a Class-A motorhome who suffered two front-end "blowouts" on the same day. There was not a lot of data provided such as actula load on each front tire or the tire age or even when the last tire inspection was completed. But here is one of the replies in the thread:
 "The reason that your coach is equipped with a heavier axle and bigger tires is exactly that the axle and tires on the earlier model Aspires were too close to what the coach was carrying. The close limits on the Aspire as well as the tire choice on OEM tires have been a well-known concern for years and many Aspire, owners, that frequent this forum have shifted their tires to tires with higher weight tolerances and inflation load-carrying specs and overall better safety record.

My 15 Anthem was similar. With me fully loaded for travel (which was still well below the coach's maximum rated weight, and tanks all loaded and us sitting in our seats, I was also overloaded on my front axle by 140# which was deemed acceptable. It was that way the whole time we owned her. A whole lot of weight is borne by these front axles on coaches this big and heavy..... within tolerances and specs but close."

I can't address the accuracy of Gary's comments on the Aspire or Anthem motorhomes but I have heard of other cases where the OE tires and even front axle in one case, was in overload when the RV was shipped from the MFG. added the following:

Individual tires don't care about the load on the other tires on a coach or the average load on all the tires. Only on the load on that individual tire. This is why "4 corner weights" is strongly recommended for all RVs.

GAWR, not GVWR is what is important for each axle BUT that is assuming a perfect 50/50% side to side split in load which is almost never the case. Some coaches have been fount to be unbalanced by 500# to over 1,000# yet still close to GAWR.

Also having a reasonable "Reserve Load" is very desirable, especially in the more critical front position. A reserve load (tire capacity minus the measured load on that tire) of at least 5% with 15% being a good goal may require changing the amount of "stuff" you carry or moving "stuff" around or even getting higher rated tires.

You can also stagger tire replacement if you have the same size tires in all positions. I cover how to do that in my post on spreading out the replacement cycle.  My post has a 1-year cycle but you could easily change that to 2 years and never have tires over two years old on the front axle.

##RVT915

Question on radial tire belt "Interply Shear" or IPS

Originally posted on Airstream forum, but the answer applies to anyone running radial tires.

"From my reading, if you see a post where the tire failed with the tread coming off AND the tire carcass still held air pressure, that is likely to be an inter-ply shear failure. It is my understanding of the issue, that inter-ply shear (twisting of the tire) breaks the bond of the tread from the tire carcass. This may start as a small section that can be seen as a bubble under the tread. Then rolling the tire expands the failed area until in all comes apart.

For what it's worth, I've seen plenty of these in various posts. I suspect it is also possible for the tread to separate from the carcass and in the process of self-destructing, punctures the tire carcass resulting in tire deflation.
Do I understand the consequences of a high level of  IPS?"

My reply:

The short answer is YES.

OK, now to the questions of IPS (nice acronym BTW).

If you have reviewed my numerous posts that mention IPS you can learn the background and the steps suggested to lower this destructive force.

All radial tires exhibit this force. It is a function of having belts under the tread that are at a high angle relative to the low angle body ply. Here low angle is about zero with the body ply running radially from bead to bead. Belts are generally in the range of 60 to 70 degrees relative to the body ply. The two belts ply or layers run in opposite direction and for the width of the tread. NOTE:  Different tire companies use a different reference for the "radial." Some call that 90 degrees and they say their belts run in the 20- to 30-degree range, but the result is the same as only your reference changes.

Do tires ever fail due to IPS? Yes, it is these forces that initiate microscopic cracks which grow over time and use. Air loss or not is not a controlling factor as air loss can occur because the belts have separated from the body, which allows tearing of the rubber between the body ply cords, which then leads to air loss. This can occur in fractions of a second so the air loss is indistinguishable from the belts and tread detaching from the body. The rapid loss of air can sound "explosive," which leads many to use the catch-all term "Blowout".


In THIS post the two PRIMARY reasons for tires to fail are covered. We are not talking about air leak here.

It is the air pressure that supports the load, not the tire construction. (Yeah, the tire does support some of the load but maybe only 5% at best, so we are discounting that.)

In general, a stiffer tire can generate higher cornering force than a tire with low inflation. Cornering force is not just from the contact area. This is well known in the racing community as our tires generally run higher pressure than we would run on the street. I know this from first-hand experience running and winning numerous road course events in my Camaro.

(6-time winner of the 24-hour race at Nelson Ledges, Lap records at 6 different tracks including Lime Rock, Mid-Ohio, Watkins Glen and others.) I ran real "DOT street tires" as required in my class, not special-purpose-built racing tires that wouldn't last 15,000 miles of street use. Those other tires were only available from race tire dealers. Most of the time I ran 34 to 36 psi cold vs. an estimated 20 to 22 psi, which is what I would have needed to simply support the actual load -- so clearly more contact area from lower inflation did not provide race winning results.


We don't need to get into the sales (price) and marketing decisions of RV companies on what size, type or brand tires they supply. We as RV owners are trying to get the best durability and overall performance from the tires we run on our RVs.

Tire durability (not coming apart) is our number one goal. You can choose to follow our recommendations or not. All I ask is that you not complain if or when you have a "Blowout" that has the root cause of the failure traced to a failure to follow my recommendations. Lowering the IPS force can be accomplished by increasing the margin between the tire load capacity at a given inflation and the actual load on your tires.

You can accomplish this with larger tires or by unloading your RV, but not everyone can do those things. This leaves increasing the tire pressure. Especially on multi-axle trailers, you need to do all you can to increase the margin, and running the inflation molded on the tire sidewall can be done by, and is recommended for, trailer owners.

Sidewall "Bubble" or ? A Tire Autopsy

Took the wife's Miata down for an oil change and tire rotation. Contacted by the store, that they had discovered a "Bubble" in the sidewall and wanted to know what I wanted to do.
After a quick look at the location of interest I concluded that we were looking at a Sidewall Impact Break. I had the store replace the tire with a new one and asked that the allow me to do a "Failed Tire Inspection".  Here is what I found.

Picture 1 is of the inflated LF tire on the car.
You can easily see the "Bubble" on the sidewall under the molded word"OUTSIDE". What tipped me off to the damage being an impact and not a sidewall bubble or blister was the shape (more radial in nature than round) and the gradual nature of the rise of the shape. Sidewall blisters are normally more abrupt.



The interior picture is what we see inside the air chamber at the location of the sidewall "bump".

I have an arrow pointing at the stress marks of the body cord on the inner liner rubber.






Picture 2 is of my initial examination cuts.   Note I did not cut directly through the area in question as I did not want to destroy or contaminate the "evidence" that I suspected would be found in the area of interest. This is an important point that many inexperienced investigators sometimes miss.

In picture 3 we see the location of interest. I added an arrow that points to area os special interest. If you look closely you will see a short dark line. This is a depression where the interior rubber has been "sucked" into the damaged area of the sidewall,




After removing the section of the tire, close examination revealed some of the initial Innerliner cracks / tears.  Here is a close-up shot.

These cracks would grow and could eventually result is air loss through small cracks in the sidewall. It is important to consider that the cracks will not grow in just a couple of miles or maybe not even in 100 miles but if driven long enough would most certainly result in an air loss. The driver would have no recollection of ever hitting a bad pothole or road debris so in all likelihood simply claim that the "Blowout" was due to some tire defect.

 Finally, we can see the separation of the body cord from the surrounding rubber. It is possible for this type of separation to allow the cords to move independently from the rubber next to the cord and the rubbing can generate heat which under the right circumstances could lead to a cord failure.
Again this could take weeks or months to progress to a loss of air but is another example of why few drivers connect the effect of a tire losing air to the real cause of suffering a sidewall impact break.

This break was actually quite minor. A more severe impact was covered in THIS post.

Not a "Blowout" but definitely was a Run Low Sidewall Flex failure. No TPMS was cause

Read the following on an RV trailer forum:
"BOOM it happened again, however, this time it was with the upgraded Maxxis tires, seems to me that a lot of these "trailer tires" are just plain garbage. 
The only positive thing I can say is that the Maxxis tires did not blow up like the TowMax tire did thus I suffered zero damage this time, call that a win-win.
All tires were checked prior to departure and filled to 80PSI, less than 20 miles to our destination (220-mile trip) I saw a bit of smoke coming from right side pulled over and the side wall gave out. 
Changed it with the spare Goodyear Marathon that camping world lovingly overcharged me for last year ($197.67 to be exact) and went on my way very slowly. 
Found a tire shop called Gattos in Palm Bay FL that had my size 235/80R16 and installed four new Goodyear Endurance tires (FYI tire shop was way less than camping world by $34 dollars per tire!)
Why 4 you might ask, well it just made sense to me kids, wife & dog in the truck better safe than sorry. Took the three good Maxxis home with me as they look fine, may use one and make a second spare tire. 
Let's hope the Goodyear Endurance tires are as good as they say at least they are made in the USA VS the Marathon that's made in China & had a really bad track record. Anyways just sharing my experience will be purchasing a TPMS system very soon before our next trip that's for sure. Any recommendations? Seems many offer a six-tire system all I need is a 4 tire system."

=============
My reply

Sorry to see you had another tire failure but there is no such thing as a "failure-Proof" tire. All tires need to be properly inflated. ALL THE TIME. Not just at the start of a trip.
The pictures provide the evidence with that nice 360 flex that resulted in one side ending up with just the bead area and lower part of the sidewall. This piece of convincing evidence is seen in upper left part of the picture.

I hope you held onto the other 3 tires as there is no reason to expect them to fail as they apparently didn't lose air like the failed tire did.
In case you wonder about my diagnosis you might review THIS blog post where I was provided with a number of sharp pictures of the failed tire.

As covered in THIS post, 99+% of tire failures are due to one of two different causes. Your tire has clear and convincing evidence of failing due to Run Low Flex Failure of the sidewall.

I would strongly suggest a TPMS be installed so you could get advanced warning of air loss.

Note: I have even seen instances where the valve core sticks open and if the valve cap is not metal with an internal "O" ring the tire just takes longer to go flat as plastic caps are really, IMO only reliable at keeping dirt and small birds out of the valve core sealing ring. You might review THIS post on valve cores to understand why metal caps with 'O"rings or TPMS sensors are the only items I consider acceptable to use on the end of a valve stem.

When to replace tires? Can you drive on one "dual"?

Was reading a magazine aimed at motorhome owners and there was an item about a man that suffered a tire failure. It was one of his rear duals. The RV owner reported that he decided to drive to the nearest tire store where it was suggested that he replace all six tires. The tire dealer had to educate the RV owner about the life of tires in RV service being 10 years or less with many recommending that tires be replaced after six or seven years life.

The magazine did offer a brief explanation on how to "read" a tire DOT serial and learn it's age.

IMO the magazine missed an opportunity to further educate their readers with a warning of the damage that was probably being done to the mate of the tire that failed.

First off there is a good probability that the tire, being over 10 years old, failed from a belt/tread separation. We can't be sure, as the RV owner didn't have a TPMS, so we don't know if he could have avoided the problem of a "Blowout" or Run Low Flex Failure on the Interstate. We do know if there was a slow air loss, the tire that did not fail was being run with ever-increasing overload, for as the companion tire lost its air the load on that end of the axle was being transferred to the fully inflated tire.

In the tire industry, there are tables that provide information on how slow you need to drive as you increase the tire load above its normal load capacity.

Basically, you need to run no faster than 40 mph if you are running 107% of the rated load.
If you want to run 113% you can drive no faster than 30 and the max speed drops to 20 mph if the overload is +21%.

Since our RV owner was running at 200% load I would estimate that maximum speed he could travel without doing damage to the "good" tire to be no faster than 5 mph and even that is questionable as there are also distance limits for those conditions

BOTTOM LINE
If you have a tire failure, no matter the reason, you need to change out the failed tire and should not attempt to "limp" home on its companion. If you are concerned for your safety on the side of the road you need to be aware that driving over 5 mph means you need to have the companion tire also replaced. No matter its age. As always when changing tires in a dual position you must also match the pair as covered in THIS post.


Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 17th year. Learn more or subscribe.

##RVT820

Why does a sidewall "blow out" when you run on low inflation?

The title for this post is essentially the exact question I was asked.
"Tireman9, can you explain why, when the tire pressure drops below a rating for a tire, that the sidewall of the tire blows out with great force? What pressure drop will cause this type of damage? When the tire blew it had enough force to damage the motorhome with the rapid escape of air that made a large bang when it blew."

My answer:
OK, let's see if i can cover the details of why and how a tire sidewall fails due to being run without proper inflation.

The mechanics are essentially the same, be it a textile (usually Polyester) tire as are most P, LT, and ST type tires, or for tires with steel body cord as most commercial grade LT tires and "TBR" Truck-Bus Radial" tires. These cords are referred to as the "body ply".

I think we all realize that tire sidewalls bend when loaded. This can be observed by simply looking at the bottom (near the road) vs. the rest of the tire sidewall. The amount of bending is essentially just a function of tire size, load and inflation. This bending includes some stretching of the outer surface of the tire and of the rubber surrounding the body ply. This stretching results in some heat being generated. You can test/experience this heat generation yourself with a simple test of holding a rubber band against your lip and stretching and releasing the rubber band rapidly. Your lip is sensitive enough to feel the temperature rise of the rubber band.

Now the rubber used in tire construction can tolerate some temperature rise. The heat generated can transfer to outside air at about the same rate it is being generated. This is what happens for hopefully tens of thousands of miles and hundreds of thousands of revolutions, i.e., sidewall flexes.

So what happens if there is a leak of inflation air? Or if the tire was not properly inflated in the first place? With lower air pressure the amount of bending increases and with an increase in bending we see more heat being generated. Increased heat generation means increased temperature of the rubber internal to the tire structure. Since rubber is a good insulator, heat transfer can be slower than heat dissipation to the outside air so the temperature can continue to rise ever faster.

The strength of the rubber decreases with an increase in temperature which allows more bending. With slower heat transfer from the internal structure to the outer surface and increased heat generation as more air leaks out, I think you can see how it is possible to get to a point where there is something like a chain reaction or "runaway" temperature increase.

The above heat generation can also result in the polyester experiencing a rise in temperature with the associated loss of strength. You have seen the effect of high heat by holding a match near the end of a piece of Nylon or Polyester rope and see the textile melting. In the steel body ply tire the increased bending can result in a fatigue failure of a steel cord. You can test the fatigue with a steel paperclip. Simply bend the paper-clip a few times and it will break. In the case of a tire the number of bends to failure can easily be in the thousands.

So what you are seeing when the sidewall fails is the result of dozens, hundreds or thousands of miles of excess rapid flexing of sidewall rubber and sidewall cords. If the bending is great enough the materials that are being bent simply fail. An explosive loss of air can occur if/when the force of the remaining inflation exceeds the strength of the body cord. Since there is an almost infinite combination of load, inflation, bending and speed involved, it is impossible to give an exact answer as to when the sidewall will finally fail.

If we have a large tire we can have significant force involved even at relatively low pressure. 20 or 30 psi can easily generate over 30,000 pounds of force.

##RVT809

"Run Flat" vs "Blowout" protection

Saw a thread on run flat fixtures to be used on the front of an RV to provide some protection against losing control if a front tire were to fail. A lot of discussion and conjecture but not many facts. Before I start it's important to be sure we all are on the same page with these terms.

"Run Flat" capability in today's tire market is a reality for passenger car tires. Tires designed and so labeled can provide mobility at reduced speed for various number of miles even after a complete loss of air. Some advertise 50 miles at 50 mph. I know of no true run flat tires for LT, Truck or RV application.

"Blowout" is a generic term used by many to describe a tire failure. This term does not provide information to tire engineers on the condition or possible cause of the failure.

"Rapid Air Loss" or "RAL" is any sudden loss of all the air in a tire.

"Belt or Tread Separation" -- This is when the belt and or tread portion of a tire separates from the rest of the tire. The carcass or body of the tire many times will still hold air.

"Run Flat Device" -- This is some equipment that fits inside a tire. It may prevent the beads from De-seating from the rim or may limit the collapse of the tire after the loss of air.

"Steering Stabilizer" -- This is vehicle equipment that may lessen the "jerk' of the steering in the event of an RAL.

I do understand the concern of some about the loss of control of a large RV in the event of a front tire failure. Yes, I have seen some of the videos and they are spectacular, but a front tire failure does not have to mean you will have a crash.

Back in the early '70s I worked extensively on a new type of tire from Firestone, the LXX, which was intended to replace 10.00-20 and 11-22.5 size tires but used a 26.5 rim. I even spent a week in Texas at the test track intentionally puncturing front tires with a 2" diameter hole to test vehicle control. While the tire worked as designed, the cost of new wheels made the tire design not viable in the truck tire market.

Here is a picture in the Akron newspaper at the time showing the tire with my then boss Ed Henry.

The main challenge for vehicle control is to either limit the "drop" when a tire suffers an RAL or to limit the steering response which can send the vehicle into another traffic lane.

There are a number of systems on the market:

Tyron is designed to keep the tire on the wheel. It does not appear to lessen the collapse of the tire.

Rodguard inserts for 14" to 17" tires appears to partially support a flat tire.

Safe-T-Plus steering stabilizers take a different approach to vehicle control.

Hutchenson seems to focus on extreme situations, such as military applications.


I recall hearing about multi-piece inserts like this one from TAC but was not able to find current info for 22.5 RV size tires.

IMO the best approach to preventing a loss of vehicle control is three steps:

1. Use a TPMS and have it set to tightly monitor your inflation. Test your sensor to confirm it reports pressure loss at the level you expect. It may not be set correctly and a test can confirm.

2. Closely inspect your tires at least annually and if possible even have your tire dealer check for out-of-round or lateral wobble of the tread and bulges in the tire sidewall. These can be early warning of separations or other structural damage to a tire.

3. Study and review the safety videos on how to maintain vehicle control in the event of an RAL.
   Here is one from Michelin, and another, and yet another.


##RVT807

When should you replace your tires?

Saw the following question on an RV forum from a motorhome owner.
"Does anyone ever just replace their front tires after 7 years? It seems that a tire failure on the front is much worse than the back. If the tires have a lot of tread and no sign of cracking, why replace the back ones?"

One reply correctly said, "There's more to consider than age. Were they properly inflated? Did you bang into curbs to damage the sidewalls? There are many failures due to improper operating conditions. Not just age."

I would first ask if you know the "life experience" of the tires:

Did the RV have a previous owner?
While they may claim they always checked inflation, can we be 100% certain?
Did you purchase the tires direct from a major tire company and know the complete use history?
Have you confirmed your load on all the tires from day one?
Did you ever discover one of your tires 20 or 30 psi low one time?

There are many things to consider, but if you are confident the tires have always been properly inflated for the actual load the following should help.

"Blowouts" (look at the picture at the top of my page), or more properly Run Low Sidewall Flex failures, happen because of running on low inflation. This can be avoided with the use of TPMS.

Belt separations, which are much less common on commercial grade tires, may occur after the rubber at the belt edges degrades due to cumulative damage from heat.

UV does not affect the internal structure of tires and external cracking is only one symptom of exposure to sunlight. I consider external cracking like having a person run a temperature. Having a temperature is just a symptom of some other illness, usually an infection. You can be seriously ill but not be running a temperature. Think of heart disease or cancer as two things that can kill you but don't cause you to run a temperature.

The suggestion on when to replace tires is only based on probability, as it is impossible to know just how much damage has been done to the components of a tire. The general suggestion is to have tires closely examined by a tire expert at 5 years and each year after that. Tires should be replaced at 10 years no matter what is visible on the surface of a tire.

I wrote a blog post on a suggested inspection and "step replacement" concept. A version of this suggestion could result in your keeping newer tires on the front, which in theory should improve your chances of not having a belt separation on the front. Of course also running TPMS will improve your chances of not having a Run Low Flex Failure too.

##RVT803

"Dry Rot" is a misnomer regarding tires

Read this on an RV trailer forum, but most of the info applies to all types of tires.

"My understanding is that there seems to be a belief or a known orthodoxy that despite external appearances, the inside could rot out and that tires that appear all fine and dandy on the outside, after that long are not on the inside?

I believe the only "proof of concept" is common anecdotal experience:

People have owned tires that appear fine that are "old yet all seems fine", and they experience unanticipated tread separation and such....several anecdotes to the point of it being a "common wisdom" best I can tell.

Beyond that, I have not seen a "more objective" verification of this...in my mind, after the death of such an "old yet otherwise in good shape and used properly" tire, an autopsy of that tire could show evidence of this "rotting from the inside"....I am not sure anyone has posted details about what that would look like (beside unexplained otherwise tread separation)?

Absence of such "more objective review", I am very very inclined to accept the common wisdom or orthodoxy on this matter until clearly proven otherwise as the cost of being wrong is potentially massive comparatively!!!!!!!!! Many many posts on this site have expressed huge regret about pushing past such "widely accepted advice"

My response to the above:
I did "tire autopsies" for decades before retiring. I have even posted pictures on my blog and have over 30 posts that have "Failure" as a label. Best advice I can give is to read and review the information on my blog. Listen to the only two (to my knowledge) actual tire engineers on RV forums: myself and CapriRacer.

"Dry Rot" is a misnomer. Rubber is a long chain polymer. The chemistry is such that the polymeric chains break down over time. The rate the chains break is related to heat and other energy (UV) input. Nothing is actually "drying out" or "rotting" in the common understanding of the word. Sidewall cracking (dry rot) is just a symptom that suggests the internal rubber compounds have probably lost some of their elasticity, which increases the potential for cracking, which may lead to separation.

There is no single answer to why some people have longer tire life than others except for the fact that some operate their tires at higher temperatures (load, speed and inflation plus ambient temperature) than other people.

Any tire can fail with a Low Inflation sidewall flex failure or "Blowout". Radial tires in trailer application are exposed to significantly higher Interply Shear forces due to suspension design that the tires on the tow vehicle - See my post on Interply Shear.

While operating a tire can help the "Anti-Oxidants" or AO's migrate to the surface, simply driving the tire is not IMO an efficient or effective thing to do, especially when we consider that cleaning of the tire sidewall, which will remove the AO's, can result in more harm that any driving around can prevent.

How many of you have bothered to make load and inflation adjustments necessary for driving your ST type tires any faster than 65mph?

Do you even know the actual loads on your trailer tires?

How many do an annual "free spin" inspection of your trailer tires?

How many are running TPMS (tire pressure monitoring systems) so you get warned when you drop down to the minimum inflation needed to support the measured tire load?

If you feel that checking your pressure with a hand gauge is sufficient, do you make that check every 10 to 15 minutes of operation? If you have a tire leaking air you can destroy it in just a few miles, so the fact you checked the air 4 hours prior to the failure is of no importance.

Sorry for the rant but the FACTS are out there. It takes a little effort to drastically reduce the potential for premature tire failure. There is no magic snake oil spray that will make your tires last 20 years. There are steps that you can take to get 5+ years of life in trailer application and 7+ in motorhome and tow vehicle application.

##RVT798

"Only" drove 750 miles with companion dual tire low on air

Quote:

Originally Posted by Charlie What should I do? I had checked tire pressure the day before and only drove about 750 miles when the right rear inside duel blew resulting in damage to the MH and the tow. Only the side wall blew and the tire stayed on the rim. This is the first time in over 25 years of RVing that I have ever had tire trouble. I only had about 14,000 miles on these tires that are less than 2 years old. I bought the best tires they recommended. I will not say the brand but it begins with M. I had pressure set at 120 psi and they were filled when the tires were cold and had not been driven for over a month, Should I be concerned about the other tires?

Should you be concerned? It depends. Why did the tire fail? If the failure was a sidewall flex failure (sometimes called a "zipper") from running low then there was most likely an active leak, i.e. puncture or leaking valve core would be on the top of my list. In this case the other tires are no more likely to fail next week than they were last week with one exception to be covered in a moment.

If you take the failed tire to a heavy truck tire dealer for the brand involved they should be able to confirm the mode of failure.

Since you were not running a TPMS (tire pressure monitoring system), all we know is that probably sometime between checking the tire pressure and 750 miles later (2 days?) one tire had lost most/all of its air. We also know that the outer dual was run with possibly 100% overload so it probably sustained internal structural damage that shortened its life (months or years). Since we do not know how many miles at what % overload, it is impossible to predict -- so the suggested best practice is to replace the companion dual.

One thing we can do is to use this as a learning experience. With a TPMS a driver would get early warning and many times can stop before a tire is damaged and, by extension, avoid damage to the RV and even not damage the mate in a set of duals. A single warning in the life of a TPMS (years) could save much more than the cost of the system.

Now as to the other possible reason for a tire to lose air. It is possible for a piece of grit to get into the valve core and allow air to leak. I suggest you review the posts on "Valves" (list to the left) and you can see an actual example of a leaking tire and the grit that caused it. So, as I have pointed out in the past, the very act of checking air pressure can sometimes result in a leak and potentially a failed tire.

##RVT797

Why do some tires "explode"

OK, let's see if I can cover the details of why and how a tire sidewall fails due to being run without proper inflation.

The mechanics are essentially the same, be it a textile (usually Polyester) tire, as are most P, LT, and ST type tires, or for tires with steel body cord, as most commercial grade LT tires and "TBR" "Truck-Bus Radial" tires. These cords are referred to as the "body ply."

I think we all realize that tire sidewalls bend when loaded. This can be observed by simply looking at the bottom (near the road) vs. the rest of the tire sidewall. The amount of bending is essentially just a function of tire size, load and inflation. This bending includes some stretching of the outer surface of the tire and of the rubber surrounding the body ply. This stretching results in some heat being generated. You can test/experience this heat generation yourself with a simple test of holding a rubber band against your lip and stretching and releasing the rubber band. Your lip is sensitive enough to feel the temperature rise of the rubber band.

Now the rubber used in tire construction can tolerate some temperature rise. The heat generated can transfer to outside air at about the same rate it is being generated. This is what happens for hopefully tens of thousands of miles and hundreds of thousands of revolutions, i.e., sidewall flexes.

So what happens if there is a leak of inflation air, or if the tire was not properly inflated in the first place? With lower air pressure the amount of bending increases and with an increase in bending we see more heat being generated. Increased heat generation means increased temperature of the rubber internal to the tire structure. Since rubber is a good insulator, heat transfer can be slower than heat dissipation to the outside air, so the temperature can continue to rise ever faster.

The strength of the rubber decreases with an increase in temperature, which allows more bending. With slower heat transfer from the internal structure to the outer surface and increased heat generation as more air leaks out, I think you can see how it is possible to get to a point where there is something like a chain reaction or "runaway" temperature increase.

The above heat generation can also result in the polyester experiencing a rise in temperature with the associated loss of strength. You have seen the effect of high heat by holding a match near the end of a piece of Nylon or Polyester and see the textile melting. In the steel body ply tire the increased bending can result in a fatigue failure of a steel cord. You can test the fatigue with a steel paperclip. Simply bend the paper-clip a few times and it will break. In the case of a tire, the number of bends to failure can easily be in the thousands.

I will cover the "explosion" in an upcoming post.

##RVT793

Surviving a tire "blowout"

I have many posts on the technology and terminology of tire failure but no matter what the cause or what you call it, a tire failure is not fun. Here is some information on what to do.

Over the past few months there have been a couple items in the news and on the Internet about tire failures on RVs and buses. The videos are pretty dramatic:
http://tinyurl.com/h4f7ykr
http://tinyurl.com/gmvclne

Many on this forum are in motorhomes. Many also pull a toad, but others own or have friends with trailers or may even find themselves pulling a trailer. I will also include some information for those times too.

First, for tire failure on a toad or trailer or the rear duals or tag of a motorhome it is critical that the driver is notified as soon as possible that there has been a failure or that one is about to occur. The only way I know of gaining this knowledge is with a tire pressure monitoring system (TPMS) that can alert the driver of air loss. Some TPMSs can even alert the driver in the first few seconds when the inflation has dropped just a few psi from the hot running pressure.

If you do not run a TPMS then you will not learn of the pressure loss before damage has been done, as you will be depending on passing motorists to get your attention. By this time, damage has been done, but hopefully the toad or trailer hasn't rolled over or separated from the motorhome, which could raise the level of severity of consequences dramatically.

For motorhome or bus drivers the failure of a front tire can mean a significantly different outcome, as there is the real potential of a complete loss of control if the wrong response is taken. Here we know that a warning of initial air loss may provide enough time for a thoughtful response from the driver, but even having a TPMS is not a 100% guarantee as there are failures that do not involve air loss. So the question then is what actions need to be taken in the first fraction of a second after a front tire comes apart?

Thankfully there is a good instructional video from Michelin of what a driver needs to do. Here is another instructional video.

Yes, the advice is not intuitive to the average driver but it can work. It has been demonstrated numerous times that there is both proper and improper driver response to a tire failure. Sadly, many drivers have ended up turning an inconvenience into a tragedy.

A driver needs to stop and think about what to do and to take a moment — frequently — to help implant the correct response so it can become an automatic response. You do have plenty of time to think about this as you drive down the highway. I would suggest that if you spent as little as 10 seconds once an hour every hour when driving, thinking about the correct response of maintaining control first then slowing down second — rather than just stomping on the brakes — the action may become automatic. We all know that practice and repetition can make athletes better at their "game." Well, in this case, practice, at least in thought, can make you a safer driver in the "job" of getting yourself and family safely to your destination a reality.


Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 16th year. Learn more or subscribe. 

##RVT769

Travel Trailer tire "Blowout" not quite.

Just got an email from a reader, in which he describes a recent tire failure he experienced on his travel trailer. He reported:

"Mr Marble,
I recently experienced a catastrophic tire blowout. I am 100% confident it was not due to low tire pressure (according to my tpms). My tpms did not alert me to an overheat or pressure issue. I was only 35 miles into my trip. It alerted to the blowout 3-5 seconds after the blowout, but I had already heard the pop and saw tire and fender shrapnel flying in my side view mirror. It was passenger front tire on trailer.
Tires are approx three ears old, around 5000 miles on them. We are weekend warriors plus 1-2 1000 mile trips per year. Rig sits 2-4 months of the year under shed cover with covers on tires on gravel.
Before I go in to details on rig and such, would you be willing to give me your opinion as to the cause of the failure? I have my suspicions but I'd like to hear from an expert.
I put the spare on and finished my trip and am sitting at ocean lakes family campground in Myrtle beach. Can take pics/video and provide whatever data you need.
Here's a couple of pics if it helps sway your decision.
RW-Myrtle Beach"

Here are the pictures he sent of his tire.

  Now many of you might think these are sufficient but for me to provide a better more accurate opinion of that went wrong I really do need better pictures.

In this case it was too late to get better pictures as RW informed me that he didn't have room to save the tire till he got home.

A few comments and observations.

The tire did not suffer a "Run Low Flex Failure" or what is normally called a "Blowout" by a non-tire engineer. The condition of the tire is more accurately a Tread or Belt Separation. The air loss came after the belts and tread had already separated from the body or carcass of the tire so that is why the TPMS did not provide any warning.

I did inform RW that the pictures were not close enough or of high enough quality to allow me to zoom in to see the details needed for me to establish a reason for the failure with a high degree of confidence but I did provide some comments.

A tire suffering a Tread Separation is simply not going to generate high enough temperature to trigger the TPMS.

It appears that this tire possibly suffered from some manufacturing or chemical problem as there are large amounts of steel cord with no rubber adhering to the steel cords. This could be because the tire had started to separate many miles prior to the external failure and the rubber was abraded from the steel cord. I would need to do microscopic examination to confirm this diagnosis.

I suggested that RW review the "Free Spin" tire inspection process that I outlined in my post on How to Inspect tires and in the post Why Blowouts are of special concern.

I also suggested that he include the Free Spin inspection procedure at least once a year so he would improve his chance of discovering an impending tire failure in the future.

A side comment about retaining the tire. If RW had wanted to file a warranty claim with the RV dealer or tire company he would need to be able to produce the tire for examination. It would also have been a good idea to be sure he had recorded the complete DOT serial and file a complaint with NHTSA for without complaints there will never be an investigation or a possibility of a recall or an improvement in the quality of tires produced for the RV market.

Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 15th year. Learn more or subscribe.   

Zipper "Blowouts" on Class-A RV

I noted in an RV forum someone was changing from one brand tire to another brand. One reason given for the brand change was because they had suffered two "zipper" failures with their 22.5" steel body radials. As I do many times when reading RV forums, I posted a link to an earlier post in this blog where I had suggested that a "zipper" failure can occur with any brand steel body radial.

As I try to support my statements with more than just my opinion I dug out an article from Tire Business magazine. In the article it was pointed out that "circumferential fatigue ruptures - known in the trade as 'zippers' in steel radial truck tires" are a failure that can have serious safety consequences and are not just an inconvenience to the RV traveler.

The article goes on to point out that "a zipper rupture is a tire failure in which the tire blows out in the upper sidewall, leaving an even line of broken steel cords exposed, which gives it the appearance of an open zipper. They are typically 10 to 12 inches long but can extend up to 36 inches in length."

The large amount of flexing can occur when a tire is significantly under-inflated. When one tire in a pair of duals looses air it can mean the failure takes longer to become obvious and in the meantime structural damage is being done to the tire that had not lost air but is now being asked to carry up to 100% more load than normal.

What makes this type of failure dangerous is that it is entirely possible for a number of steel body cords to have failed but the rubber in the sidewall has not ruptured at the now low inflation pressure. If that has occurred and the RV owner happens to discover a tire with low pressure then decides to "fix" things by re-inflating the low tire, the damaged tire may now rupture with explosive force when higher pressure air is introduced to the tire.

If you wonder what can happen when a tire explodes a simple Google search of "tire explosion" will return just too many results. Or you can watch this compilation video and ask yourself if you would want to be adding air to any of these tires.


Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 15th year. Learn more or subscribe. 

SAFETY WARNING Sidewall "Blowout"

Having a tire sidewall failure is one thing that can really spoil an RV vacation. What some fail to realize is that there is also the real potential of personal injury if a tire "blows out" when someone is near by.

The Rubber Manufacturers Association has published some guides on the proper way to handle this potential safety issue. I would like to offer part of that information here. My intent is not to scare you but to inform you that working with tires with high inflation levels is not an activity to be taken lightly. There are practices and procedures that need to be considered if or when you are confronted with the need to inflate or re-inflate your tires.

Steel body tires are usually large tires such as 19.5" and 22.5" but some 16" and 17.5" tires also have steel body cord. You should know what is in your tires and this information is molded on the sidewall of all tires. The material - Steel, Nylon or Polyester are used in most tires today. What we are primarily concerned with is the material in the tire sidewall.

Steel body tires can damage their body cord, no matter how low a speed, if the tire sidewall is over-flexed. Over flexing can occur because of over-load or under-inflation or a combination of the two conditions.

According to the RMA "Permanent damage due to operating a tire underinflated and/or overloaded cannot always be detected. Any tire known or suspected of being operated at 80 percent or less of normal operating inflation pressure and/or overloaded could possibly have permanent sidewall structural damage (steel cord fatigue).  Ply cords weakened by underinflation and/or overloading may break one after another, until a rupture occurs in the upper sidewall with accompanying instantaneous air loss and explosive force. This can result in serious injury or death."

In other words, if your normal inflation is 100 psi but you discover you have a tire with 80 psi or less you should NOT re-inflate the tire yourself. If you discover a tire has lost 20% or more of its pressure while being operated you should step away from the tire and contact a service company. All the air should be let out of the tire by removing the valve core.

There are a number of steps that need to be followed. A Safety Inflation cage like this

 is also required. The tire is inflated in steps, with the valve core removed.

I know that many people have posted questions on various RV forums asking about what compressor to use to air up their tires, but I am concerned that few realize the potential danger of inflating a tire that has been damaged. Even with 40 years' experience of inspecting tires I cannot be 100% certain the tire has not been damaged.

The best thing to do if you have any question is to have the tire demounted and inspected by a qualified technician at a tire store that sells the type and size tire you have. Not every tire store has the proper safety cage to inflate high pressure tires.

IMO, having a TPMS is one of the best ways for the RV owner to know if a tire is losing air so the RV can be stopped before the tire has lost significant air pressure and is still driven on.


Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 15th year. Learn more or subscribe.   

"Why do so many RV tires seem to be failing?"

 Well, that may seem to be a reasonable question but in my opinion it is based on what is often inaccurate failure analysis. In reality, tires fail for a relatively small number of Root Cause reasons that can be discovered, but it does require detailed and sometimes exhaustive investigation. By "Root Cause," I mean the initiating feature or condition that eventually led to the failure. Too often people confuse the tire's ending condition with the initiating or "Root Cause" reason for the tire to end up in the condition they are observing.

For the last few years of my 40-year career as a tire engineer, my primary job duty was to investigate failed tires that had conditions that were hard to understand or provided confusing and sometimes contradictory evidence as to the Root Cause for their condition. With that background, I have developed some guiding principles for the most likely reasons for tires to fail.

These are, in no special order:
1. External Damage. These include punctures, cuts, impacts, wheel and valve failures and similar conditions.
2. Run Low Flex Failure. This is best described by the failure of the tire sidewall due to excessive flexing. The flexing is the result of operation when the tire is significantly under-inflated.
3. Belt & Tread Separations. This is when the belts of a radial tire detach from the body or from each other and/or when the tread rubber detaches from the top belt.
4. Manufacturing Defect. For the purpose of this discussion this would be when components of a tire were not manufactured to intended specification.

The "Why" for some of these are obvious, such as the External Damage category.
Others can be further traced to various contributory reasons.

Run Low Flex Failure This is a more accurate description of what some incorrectly call "Blowout". When a tire looses significant inflation air they flex much more that the body cord can tolerate. Excess heat is generated which can, in extreme cases, result in the Polyester actually melting. I showed examples of what this can look link in THIS post. Polyester is used in most Passenger, ST type and LT type tires. Steel body tires are used on most Class-A RVs, the steel can fatigue. I covered "Zipper" failures and steel fatigue in THIS post.

Belt & Tread Separations occur primarily because the rubber around the belt cords or between the belt rubber and the tread rubber isn't strong enough. Now it can be weak for a variety of reasons. Some might be design, some might be manufacturing and some weakening can be caused by cumulative improper service conditions.

Now let's talk about tires made by a reputable company, i.e., one that has tire stores and dealers with physical stores and sells tires that have a warranty of two or more years.
If this tire is subjected to thousands of miles of lower inflation or higher loading or operation at higher speeds or stored is full sunlight it is reasonable to expect the strength of the belt & tread area rubber to loose a good portion of its strength primarily due to the increased operating temperature of the tire. If this tire is in service on a tandem axle trailer then there is also increased Interply Shear which can overload the belt area rubber. The combination of the above may result in a belt or tread separation.

Another possibility is a Manufacturing Defect. These usually occur in small numbers as tires are built in batches so the substitution of the wrong type of rubber may cause tires to fail. It is important to understand that in almost all cases this type of "defect" usually shows up at early life of the tire. It is also very important to understand that unlike some lawyers, engineers deal in facts and logic. Simply having a tire fail is not in it self proof of a defect but all to often that is the position that those in the legal profession seem to jump to. That approach may result in a nice payout to the lawyer but will not result in product improvement as there has been no determination or identification of the actual initiating "defect".

Finally there is the possibility of a design weakness. Now I do not believe that anyone is intentionally designing tires to fail but this sometimes may occur when the performance goals of the manufacturer are limited to meet the bare minimum for strength and durability and the focus is primarily on low cost. There is no absolute way to identify these tires but I do believe there are indicators when looking for tires that are made to a higher standard of quality and durability.
I would consider a tire company reputable if it had a chain of stores across the country. If the tires carry the name of the manufacturer and have a multi-year warranty the longer the better then they probably have higher durability requirements than those established by DOT.

 For ST type tires I would look for tires with a Speed Symbol of "L" (75 mph) or faster. Now a side point about speed. I did a POST a little while ago on the topic and strongly recommend you read it. I do not think I would recommend any tire for general use that does not have a speed rating molded on the sidewall.

I do hope this post will help some to have a better understanding of what can contribute to tire failure and consider what you can do to lower the chances of having such a failure.

Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 14th year. Learn more or subscribe.