Why-don't-rv-tires-get-recalled?

 I read this question on an RV forum. It was asked by someone complaining that there were no recalls of what he considered "crappy" RV tires. Other posts in the thread went on to say that complaints to the BBB or the tire importer won't accomplish much. I posted a reply pointing out that expecting the National Highway Traffic Safety Administration (NHTSA) to recall tires when there had not been any usable complaints filed, was simply unrealistic.

NHTSA is the government agency charged with the responsibility of writing and enforcing the regulations necessary to achieve improved safety of vehicle systems and equipment. However they cannot order or even suggest that a vehicle or component be recalled without facts and data being collected and analyzed.

A while ago I worked with a reader of this blog, John B., who understood the necessity of providing the information NHTSA needs. He had suffered three tire failures. Luckily he discovered the failures before the tires suffered a detachment. In his case there was no loss of air and no flailing of tire pieces. What he did have was a tire that was no longer round or having a uniform tread contour.

Now lets be sure we all have the same understanding of the terms. In this case a "Detachment" would be when a part of the tread or tread & belt package came apart from the rest of the tire. This type of failure can result in damage to the RV as pieces flail around hitting fenders and the side and undercarriage of the RV.

    John wanted to file a complaint with NHTSA and he wanted to be sure his complaints would be useful to the engineers. He understood that partial or incorrect information would result in no investigation and with no investigation there was no possibility of any action being taken to remove "crappy" tires from use. So John contact me and I walked him through the process of collecting all the details needed. He also wanted to  dissect his tire so he could ship the important parts to me for further examination.


When I received the sample I first cut the tread in the locations John had identified but found no serious issues.

I then called upon my 40 years of experience and took the time needed to visually examine and take measurements with special tools to identify a location that was more probably of interest. After cutting the section at the location of interest and found the separation between the belts that was almost all the way across. This separation allowed the tread area to bulge out to the shape seen in the picture of the tire at the top of this blog.
For those interested these tires were not made in China as we decoded the serial and learned they were made in Mexico.

With the physical examination complete, John was able to file the three complaints with NHTSA. Now it is important to remember that NHTSA has budget constraints so investigations need to be prioritized. Obvious defects that result in physical injury would receive top priority. Also a single or small number of complaints will be of lower priority than a large number so if the only complaints NHTSA receives on these tires are the three from John there may not be any action. The same situation would apply to any complaint you might file BUT it is important to remember that if the majority of people with tire problems only post to RV forums or grouse to others around the campfire nothing will ever happen or result in the quality of tires improving.

Here are Links to John's information. Link 1     Link 2

A quick review of the complaint on file will show that the majority are of little or no value to NHTSA as the owner didn't provide the crucial information of a correct and complete DOT serial. Many complaints don't even provide the tire size or even the correct tire brand. I believe that if people spent half the time they do on RV forums but provided complete and accurate information to NHTSA we might all end up with better quality tires on our RVs.

I am working on another post on the topic or how to provide meaningful information to NHTSA.

BOTTOM LINE
If you have a tire problem you need to collect the facts - Size, Brand, the complete DOT serial and collect some good sharp pictures in case NHTSA needs them. Then make the effort to file a complaint. Who knows, you might just be able to grab the interest of the engineers and have an investigation started.

##RVT985

Is there a specific "Safety Margin" on tires?

Read a question on tire "Safety Margin" 

I pointed out that the term "safety" margin really doesn't apply to tires but a "durability margin" might be a better way to think about tires.

Tires seldom, if ever fail as soon as they are run 10% overloaded or run 20 psi low or 10mph over their stated speed rating.
Damage is cumulative and I don't know of any automotive parts that "repair" themselves. In some mechanical parts the damage is in the form of accelerated wear. For a moment think of running your engine low on oil. Will the engine fail if you run it 5% low or 20% low or 80% low on oil? In how many miles? I don't know the specific answer to the number of miles based on how low on oil you are. Does the fact that you might not have an immediate engine failure from running 50% low on oil mean it is OK to do that?

In tires, the damage starts at the molecular level with chemical bonds breaking (cracking) which can grow and may become microscopic in size and eventually might result in cracks that grow large enough for the structure to fail. i.e. a belt separation.

Overload or low inflation or over-speed, lets call these damaging events, can each initiate or contribute to an accelerated growth of these "cracks". In rubber there is both an initiation phase and a growth phase.

It is conceivable for tires to tolerate "X" level of damaging event for many thousands of miles and the tire never "initiates" a crack but also there can be a single damaging event such as hitting a pot-hole of a certain size, depth, length, angle of incidence and speed that is the "initiation" event and this results in a belt separation 5 miles or 20,000 miles later, with the variation be the result of different growth rates. This was covered in detail in my blog in Jan 2020. I examined a Tire Industry technical paper on tire forensics and impact damage that identified a 100% correlation between impact damage (such as you might get hitting a pot hole) and belt separation failure.

Many times I read reports from RV owners saying..."I was driving 55 mph down the Interstate and had check the air just an hour previous and was not overloaded when the tire failed for no reason." Sorry but there is always a reason. That reason might be because of the speed, load, inflation road surface, i.e. damaging event, that the tire was driven on 1,000 miles previous to the actual failure.

Forensic tire analysis is a very complex science and there are very few engineers that have the decades of experience it takes to accurately identify the Root Cause of tire failure. I dare say that each major tire company has a handful of engineers capable of correctly identifying the actual root cause of a tire failure 70% of the time. While they may not be able to identify the actual Root Cause they probably have been trained and have enough experience to know if the tire should be "adjusted" as a "customer satisfaction" case but maybe only one engineer that can properly identify 90% of tire failures and be able to issue a technical "white paper" offering the evidence to support their detailed opinion of the originating root cause for the eventual failure. Too often there is too much missing evidence or accurate reporting to tire operation history for anyone to identify the reason why each and every tire failed. 

Since learning all the important facts of the tire's operating and life experience it is very difficult to be able to  identify the reason for every failure. Even if there is physical evidence of the tire hitting a pot hole you can see in the data of the Jan 2020 blog post that you still can't provide a reliable answer such as. You hit a pot hole 5,678 miles ago and that is why your tire failed.

Back to the question of "Safety Factor or Margin". All tires sold for use on US public highways are to meet a series of tests such as speed, load endurance, staying on the wheel with low inflation etc. Tire companies also have their own minimum performance standards that tires are suppose to meet. Tires are not graded such that they pass 85% of the tests or that 90% of all tires made must be capable of passing all the tests. The laws for tire safety are written such that 100% of the tires sold must be capable of passing 100% of the tests. 

Each tire company tests tires beyond the minimums and using statistical data analysis they can predict that the performance required on any individual test tire such that 99.96% or some similar number, of all tires made will be capable of passing the DOT testing when new. Tire companies have whole departments constantly looking at test tire results and result variation in an effort to be confident they are making good tires.

What tire companies can't do is predict how much any individual RV owner will overload or under inflate their tires so it is impossible to come up with some specific "margin" of acceptable overload because the other factors such as speed, ambient temperature during operation and level of under-inflation are unknown and too variable to allow prediction of durability.

##RVT972

"China Bomb" tires

I continue to see people talking about 'China Bomb" tires. As an engineer, this makes me a bit sad that so many people appear to have such a poor understanding of the difference between "causation" and "correlation".

While it is true that a majority of the tires on RV trailers that fail were made in Asia, and for many folks that meant "China".

But I would ask if 90+% of the tires applied to RV trailers were made in "China" why are you apparently surprised to learn that 90+% of the tires that fail in RV trailer use were made in "China"?

In an effort to make the difference between "causation" and "correlation" a bit easier to understand I  have sometimes offered the following example.

If you check with people in prison you will probably find that 90+% have eaten McDonald's fries. So, therefore, it could be concluded that eating those fries can be considered something like a "gateway drug" to breaking the law and ending up in prison. I think we can see that that conclusion is not sound or reasonable but clearly the numbers are similar to what we see in the RV community.

Yes tires in RV Trailer have shorter life than in other applications but  major reasons for the higher rate is clearly a combination of the documented very high percentage of RV Trailers with tires in overload/under-inflation as well the clearly identified impact on belt separations due to Interply Shear due to the suspension design of multi-axle RV trailers.

##RVT885

Why do trailer tires fail more often than tow vehicle tires?

Here is the question posted on a travel trailer forum.
Why so many trailer tire failures and so few, if any, tow vehicle tire failures?

This post could be considered Part 2 of my post of last week. 

The primary reason IMO is staring everyone in the face and the information is molded onto the tire sidewall so you do not need to be an Einstein, but almost everyone chooses to ignore the science so they can save a few bucks.

Fact: Tire load capacity is a function of air volume (tire size) and inflation pressure. This is well established and is confirmed by every Load & Inflation chart printed. Increase size or increase pressure and you increase load.

If we all drove around on tires with LT level sizing and inflation there would be almost no failures other than those caused by road hazard or punctures.

BUT
People want softer ride, better fuel economy and lower cost so alternatives were introduced into the market.

LT tires can be considered the standard for tires designed to carry load at highway speeds.

P type tires have a higher load capacity than identical size LT tire but if you check the actual load on most car tires, you will see they have 15% to 25% or more "Reserve Load" capacity (more capacity than needed). Inflation is set for cars based not on load but ride, handling and fuel economy. You also know that P tires must have their load capacity de-rated when P tires are used in truck, SUV or trailer application. When P type tires are run with zero reserve load you will probably get more failures. (See Ford Explorer crashes.)

ST tires have a higher claimed load capacity than LT tires and TT companies use the smallest (lowest cost) tire that can, most of the time, meet the specification for load.

How then is it that ST tires are rated to carry more load?
The load formula for ST tires is based on a 65 mph Max operation speed and an expected shorter life. The formula was developed back when bias tires that wore out at less than 15,000 miles were the norm

Since 1990 when ST tires were still "Alpha" sized ( H78-15ST) the load formula has not been changes as far as I can determine.

The science indicates that if you want tire durability on your trailer as you get on your truck maybe you need to consider running the same type tires i.e. LT type and of course that means you also need to use LT Load & Inflation limits.

Here is some info I posted Sept 14 2011

"Here are some facts from the Tire & Rim Association industry standards book 

P235/75R15 105S (Standard Load -35 psi @ max load)
2028# 35 psi 112mph on a Passenger car
1844# 35 psi 112mph on a SUV or P/U or trailer (no Dual)

LT235/75R15 LRC
1512#single 1377# Dual 50 psi 85mph

ST235/75R15 LRC
2340#single 2040# Dual 50 psi 65mph"

NOTE I did not mention the actual load on a tire but only the specified max. Weight data indicates many TT have one or more tire in overload.

"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

Is your TPMS warning psi set correctly?

Originally Posted by Dan O.

"The 'Safety Steer' is definitely a good bit of insurance. I also run the tire monitor system on all six MH tires and the four race trailer tires. I run 110 pounds in the coach tires and did pick up a nail in a steer tire one day. At 80 pounds the tire alarm went off (handling felt the same) and I saw 40 degrees more temperature in the low tire. Point is, some other warning signs are sometimes there before you experience an actual blowout."

I suggest you change the warning psi level. Many TPMS come with a single warning after a loss of 20% from the cold inflation. We all know that when running, tire inflation can increase 10 to 20 % from the CIP (cold inflation pressure). I would suggest that if your CIP is 110 then the warning should be no lower than 100.

Some TPMS provide early warning and alert when the hot pressure has dropped faster than normal so you can gain seconds to minutes advance warning if the TPMS provides "rapid air loss" warning or some other warning based on the hot pressure.

For example
Based on weight my small Class-C needs at least 65 to support the measured load. I use 75 as my CIP and my warning level is 65. My normal hot pressure is 80 to 85. If I pick up a nail I would get a warning if a tire looses more than 3 psi in a couple minutes so I might get a warning at 77 to 82 psi, which is well above the minimum needed by the tires for the actual load.

If a tire loses 20% of the air needed to carry the load it is officially "flat" for warranty purposes so there is a potential that the driving as Dan did with the tire down at 88 was damaging the tire structure which could shorten its life by months or years.

According to the U.S. Tire & Rim Association the warning signal from your TPMS should go off if inflation ever drops to below the level needed to support the actual load on any tire.

##RVT796

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.


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##RVT769

Can you "contain" a tire failure ?

I read a story about someone that had a couple of tire failures on their trailer. He was trying to build a solid steel shield over the tires in the wheel well in an attempt to contain the "Exploding " tire.. I offered a reply...

Sorry, but IMO trying to "build a shield" just is not a reasonable approach. I doubt that you can spare the 500 or more pounds of steel it would take for the shield and structure to support the shield. Since a failure of a tire can be explosive event a solid wall will not let the force dissipate. You need an open grate. Check out this video  to see the forces involved and note the damage to the steel 'safety cage. Note that most of these did not involve a tire spinning at 50 to 65 mph which would add significant force to any explosion.

You need to remember that tires simply do not fail catastrophically without some reason. There is no magic involved.

Starting with a new tire...
1. It can fail in the sidewall if it is run at highway speeds (30+) while significantly under-inflated ( 40 to 80% low). Polyester melts. Steel tires do not need the speed but steel fatigues so after maybe a couple thousand cycles you get a "zipper" failure. Properly functioning TPMS can warn of the air loss in the first couple seconds of a loss ( of just a few psi for some brands). In most cases this early warning will come way before the tire has lost enough air to result in steel fatigue or body cord melting. If you have a TPMS have you tested it? Can you hear the buzzer over the loud radio?

2. Radials can have a belt/tread separation. This takes many hundreds or even thousands of miles to grow large enough for the tire to come apart. This is where the close inspection in my blog post comes in. As I showed a tire with even significant separation does not have to come apart at once but it does leave visible clues.

The reason for belt separation is a combination of initial tire design and material selection and the long term use. Initial design can not prevent all damage done through excess heat and age but current technology in first class radials should deliver 5-6 years or 30 to 60,000 miles at specified inflation and a max of 80% load, except for multi axle trailers.

Due to trailer suspension design there are unique forces "Interply Shear" placed on TT tires that result is about 24% higher shear forces than seen in motorized vehicles. This means you would need to run very much decreased load ( maybe -25% to -50%) to get the same life on a TT application than the same tire on a TV application.

I do not know of any direct comparison real life testing so can only guess at the above figures other than the 24% that comes from Finite Element computer simulation that is a well developed tool in automotive circles  other than the RV industry.

Rubber strength degrades with time and heat with HEAT being an over-riding contributor. Do you cover your tires with white covers? This can result is a very significant lowering of tire temperature. Every hour of full sun exposure can be equivalent to two to 3 hours of use running down the highway at top speed.

Quick example: 8 hours a day 7 days a week for two months each summer can be the equivalent of 10,000 miles use as far as rubber degradation is concerned. So if we assume a tire is good for 40,000 miles  and you park it as in the above example after 3 years you may have "consumed the equivalent of 30.000 mile tire life, just while parked.

IMO making some effort to prevent a failure in the first place (TPMS & frequent inspection) would be a better use of time and money than trying to prevent damage to the RV with some sort of shield. 

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Post a complaint with NHTSA - Part 3

 Lets finish up this thread.

How to write a useful Description of tire failure for NHTSA

Lets take a short break from all those screen shots and review how to write a meaningful "Description" of the failure as seen in Step 1 of my post of Jan 8.

You need to remember that NHTSA needs facts if they are to take any further steps as they consider if an investigation is warranted.

Just ranting "My tire exploded, tore up my RV and I want new tires and compensation for the repairs and my expenses." is not useful to NHTSA. If you can't be bothered to provide critical information such as tire DOT serial why should NHTSA make an effort to investigate? Other information such as location of the incident, your cold inflation and info on what warning you received from your TPMS, if you still have the tire and can provide pictures or contact information on who has the tire, would be bonus information and potentially very helpful to the engineers at NHTSA. I previously outlined the MINIMUM information needed in my post on Dec 31 2012.

Here is an example of an actual complaint #10262837    "I  OWN A 2004 GMC SIERRA 3500. THE VEHICLE HAS POWER KING TOWMAX TIRES, SIZE LT235/80R16E. WHILE PULLING THE TRAILER AT 65 MPH, THE SIDEWALL ON THE PASSENGER TIRE BLEW OUT."

Looking at the Power King catalog on pg 10, I do find a Towmax STR in ST235/80R16 LRE size but ST type tires are not approved for use on passenger carrying vehicles such as a GMC 3500 pickup. Moving on to LT tires on pg 14 & 15 I find no metric sizes such as LT235/80R16.

So we are confronted with a few questions.   Did the owner provide the correct tire name but wrong size?
Did the owner provide the correct size but wrong tire name?    Did the owner mean the tire on the passenger side or that the tire was actually a passenger type tire?   Was the tire that failed on the GMC?
No mention of an RV or trailer brand is made by the owner. I also note that the tire manufacturer is entered as Cooper Tire and Rubber Co but according to my contacts at Cooper, they do not have a Power King or Towmax tire line and have not made ST type tires for many years.

If you were NHTSA would you consider this person a reliable witness to what actually happened  with a tire?

Now you are wondering what a good report looks like. Lets look at #10471651
" THIS COMPLIANT IS FOR A TANDEM AXLE TRAILER TIRE FAILURE USED ON TRAVEL TRAILER CAMPER. THERE ARE THREE TIRES FAILURES WITH THE SET OF FOUR ON MY TRAVEL TRAILER. THIS REPORT IS FOR THE FIRST TIRE. THE TIRE IN QUESTION IS A DENMAN ST225/75R15 LOAD RANGE D. TYPE: ST EXPRESS RADIAL DOT CODE: 4FEH M5M 1908 TIRE INSTALLED: 4-5-2009 FIRST TIRE FAILURE OBSERVED ON 4-21-2012 MILES USED UNTIL FAILURE NOTICED, 10,164 MILES TOWING SPEED: 55 TO MAX OF 60 MPH AS STANDARD TOWING SPEED ON HIGHWAY. AIR PRESSURE OF 65 PSI CHECKED AT THE START OF EACH CAMPING TRIP. TIRE FAILURE OCCURRED WHEN THE TIRE WAS MOUNTED IN THE LEFT REAR POSITION. I HAVE CERTIFIED SCALED WEIGHT SLIP THAT CAN BE PROVIDED OF THE CAMPER AFTER THE FAILURE.
THE REAR AXLE LOAD IS 4,040# ON BOTH REAR TIRES. THE TOTAL RATED CAPACITY OF THE REAR TIRES ARE: 2,540 X 2 = 5,080# AT 65 PSI COLD PRESSURE. CAMPER VIN [XXX] CAMPER MANUFACTURE: SUNLINE COACH COMPANY, DENVER, PA MODEL TRAVEL TRAILER: SOLARIS SR, T310SR, GVWR: 10,000# GAWR: 10,000# I AM THE ORIGINAL PURCHASER OF THESE TIRES WHICH REPLACED THE ORIGINAL TIRES ON THIS CAMPER. THE SIZE, LOAD RANGE AND INFLATION PRESSURE MATCH THE OEM TIRE PLACARD. I HAVE PICTURES AND CAN SEND IF NEEDED. THE TIRE HAD A TREAD BULGE INCREASING THE OD OF THE TIRE IN AN APPROX. 180 DEGREES OF THE TIRE AND WAS FOUND DURING CAMPER AXLE MAINTENANCE. THE TIRES WAS REMOVED FROM SERVICE UPON FINDING ON 4-21-2012 BEFORE TOTAL FAILURE OCCURRED DURING TRAVEL AND TO PREVENT CAMPER DAMAGE. THE TIRE WAS SENT TO A TIRE ENGINEER AND SECTIONED FOR ANALYSIS. NAME CAN BE PROVIDED IF NEEDED. I HAVE PICTURES THAT CAN BE PROVIDED TO MATCH WITH THE ENGINEERS REPORT ALONG WITH HIS
NAME AND ADDRESS. THE REPORT DECLARED THE TIRE FAILED DUE TO DETACHMENT. THE FAILED TIRE WAS REPLACED WITH A NEW TIRE OF THE SAME SIZE AND LOAD RANGE, HOWEVER A DIFFERENT BRAND. I HAVE ALL PICTURES AND REMAINS OF THE TIRE IF NEEDED FOR FURTHER INVESTIGATION."

See the difference?

You do not need to write as detailed a complaint as in the last example but IMO the MINIMUM information you need to provide would be:

1. A brief description of the tire condition, i.e., "Tread and belts came off" or "sidewall disintegrated"  along with a list of damage done to the RV with the associated costs would be desirable.

2. Vehicle VIN - This is on the vehicle label and probably on your registration slip.

3. Tire DOT serial - The complete serial number including the date code at the end.

4. Brief statement letting NHTSA know if you have additional information such as: "I have photographs of the tire" or where the tire is: "Tire is in my possession" or "Tire delivered to Fred's tire in Anytown, USA.

5. If you were using a TPMS that would definitely be information I would include.




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How to Maximize tire life with minimum effort

If you are new to the RV lifestyle or an old hand with many thousand campfires under your belt, there is one thing that is true: What you knew or learned about tires from years of car ownership probably did not prepare you for the task of maintaining the tires on your RV. This is true if your RV is a 18’ Travel Trailer or a 45’ Diesel Pusher.

I think we all understand the concept that a system is no stronger than its weakest link. For many RVs, the weakest link that can interrupt long term, problem free travel are the tires. Car tires have evolved with improved durability and reliability to the point that many people may never need to touch their tires or even know how to change a tire. Today, some cars don’t even have a spare tire and if they do the driver may not have even bothered to learn where it is as the expectation of needing to use the spare is so low it has completely dropped off the radar screen.

As a retired Tire Engineer with 40 years experience in design, evaluation and quality assurance of tires I would like to offer some suggestions that I believe if followed, will lead to many years of problem free travel. I also believe that once you take the initial steps I outline, you will also find that you will only need to spend about 15 minutes a month, or less on average with tire maintenance.

The basics that are needed to have a tire problem free experience with your RV tires involve two simple steps:

1. Knowing the proper level of tire inflation on your personal RV and

2. Ensuring your tires are always inflated to that level.

There it is, just two simple and rather basic steps and, you don’t need to be experienced in vehicle mechanics or tire engineering to accomplish these two steps as I am going to share the steps that have worked for me and thousands of others for decades.

Step 1: Knowing Your Proper Inflation

So the first step is to know the proper level of tire inflation on your personal RV. The important concept here is “Your RV”. Not the RV your brother-in law uses, or the inflation the guy in the campsite next to you uses, or even the level provided by the RV manufacturer on the tire certification label, otherwise know as the “Tire Placard”. Now some will point out that the RV manufacturer has the responsibility to inform you of the minimum tire inflation you should use, and this is correct, but this is based on an assumption which may mean the numbers are too high or too low for your RV when you have it packed with the stuff you want to take along on your next trip.

This step takes the most effort, but you really only need to do it once over the years you own your RV – unless you make a major change such as add a generator or refinish the interior with granite counter tops; you know, do something that significantly changes the weight of the RV.

To learn your real weight you need to pack your RV with all the clothes, food, fuel, water and other “stuff” you expect to carry, including the proverbial "bowling ball collection." Once it is fully loaded, you and the family need to take a short trip to a local feed store or gravel pit or truck stop that has a large truck scale with enough side clearance that will allow you to get the tires from just one side of the RV on the scale. Obviously you will need to do a bit of preparation to find such a scale, so some time on the Internet or with a phone book is in order. It is suggested that you review the worksheet before heading off to the scale so you get all the facts you need in one trip.

Here is a company that travels the US and specializes in properly weighing RVs and giving the owner the load numbers for their personal unit.  " RV Safety & Education Foundation (RVSEF) This leader in safety education in the RV community offers wheel by wheel RV weighing services for all types of RVs.

Resources

If you will not be in one of the locations where RVSEF is offering their services then you will need to do a little research, as not all truck scales have the side clearance needed. You should know that some truck scale operators discourage side to side weights and have installed guard rail to prevent this. When you check out the work sheet you will have a better understanding of what is needed.

Our friends at Fifthwheel St have a web site has information including a video that focuses on trailers but has video showing the process which is similar for motorhomes.

Bridgestone has a page just on RV tires with a worksheet for calculating tire loads

Goodyear has a nice site too

Here is the Michelin RV tire page

If you look at more than one of the above links I think you will see that everyone offers the same basic information on the process. You do not need to worry about which worksheet you use as the math is the same for everyone.

After you complete your worksheet you should know the actual load on each tire position. The next step is much easier and also only needs to be done once. You need to confirm the minimum cold inflation your tires need to carry the load. It is always a good idea to use the tables published by your brand tire. Here is my blog page with links to many different brand tires. Simply go to your brand, find the table that has your size tire and look for the inflation that supports your load or more. Don't worry if your brand doesn't offer tables as almost all companies follow the same published industry standards.

Also don’t be tempted to go to a lower level of inflation if your numbers are close. Always go up.

Now you know the minimum Cold Inflation Pressure or CIP.  Wait! What do I mean by CIP? Whenever tire inflation pressure is measured or set the tire needs to be cool and at the same temperature of the air and in the shade. This means not having been driven on or in direct sunlight for at least 2 to 3 hours. Tires get warm when moving and the Sun heats them up which results in a higher temperature which results in artificial increase in pressure. Many people simply do their tire pressure check in the morning before starting out or late evening after a day of travel. Either way the tire needs to be cool and in the shade when you check your pressure.

I feel the CIP needs to above the minimum needed to carry the load as if there is a drop in temperature you may end up below the minimum if you cut things too close. I suggest you run +10% above the Minimum for your personal CIP.

A couple of details and a suggestion:

All tires on each axle should have the same inflation. This means that whatever inflation numbers you have for your tires select the highest from the tires on any one axle and use that number for all tires on that axle. This will give you more uniform stopping and steering response.

Over the past few years technology has evolved that allows you to monitor your tire inflation as you drive down the road and can warn you if you pick up a nail or other damage. You have this in your car and it is that little orange symbol with the exclamation point in it.

and now you can add this safety feature to your RV trailer or motorhome. It is called a Tire Pressure Monitor System or TPMS for short. A quick internet search will identify a number of units specifically designed for RV application or you can review THIS web site for a discussion of features to consider when shopping for a TPMS.
A bit of Truth in Advertising here. This blog is currently sponsored by Tire Traker brand TPMS. As you might expect that is the brand I have run for years. What you may not know is that I bought my TPMS from Traker before I started writing this blog.
One nice feature of having such a system is you do not need to get out with your digital pressure gauge and check your tires every day of travel as the TPMS will let you know your inflation in the morning while you stay inside with your coffee and more importantly while going down the road. You will quickly learn the details of your pressure reading in just a few days of observation.

So there you have it. Get the RV weighed when fully loaded and do the calculations using the worksheet to learn the actual tire loading and the inflation your tires need.

Step 2: Ensuring That Inflation Is Properly Maintained

This step is much more straightforward. Just check your tire pressure every travel day, or better yet get and use a TPMS (Tire Pressure Monitoring System) to constantly monitor your tire pressure. I even set my low pressure alarm level so I would get a warning before the pressure drops below the minimum inflation I need to support the measured load on my RV.

I believe that if you follow this advice you should reduce what otherwise might be a less than 5% chance of having a tire failure to less than ½% chance of tire failure.


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When to file a complaint with NHTSA

I have previously strongly suggested that when people have a tire failure they need to file a complaint with NHTSA.

Got this question "Thanks, Tireman. My next question is when is it appropriate to report to the NHTSA? After any flat? Or are there specific indicators?"


Excellent question as we don't need to be "crying wolf"

If we start at the end of the process I think it will help us understand when and why we would want to contribute to the database of tire failures.

I think we can sum up the primary objective for NHTSA as to decrease the number and severity of injury or accident costs due to a failure of an automotive system or component. One way to achieve that goal would be to hold the manufacturer responsible for providing parts that deliver reliable service for normal and expected operating conditions.

One way to hold a manufacturer accountable and maybe "hold their feet to the fire" is to order and require a manufacturer to replace a part that has been found to have an abnormally high failure rate due to either design or manufacturing problems.

Based on data submitted to NHTSA, that agency decides if an investigation should be started. The investigation could be limited to a review of test and manufacturing data or it could involve NHTSA conducting it's own tests.

So what data does NHTSA use to decide it an investigation is justified? There is suppose to be a combination of warranty data from the part manufacturer plus a review of complaints filed by individuals.

This presents a problem for NHTSA. How should they judge consumer complaints when they know that consumers seldom have the technical knowledge to do a proper or thorough evaluation of a product failure?

So the question really is.... Should the tire manufacturer be held responsible for a tire loosing air due to puncture or leaking valve? It may be difficult or nearly impossible for the consumer to do the proper investigation to learn the root cause of the failure.
It is well documented that over half of RVs on the road have one or more tire in an overload and or under inflated condition. Should the tire company be held accountable for an overload or low inflation?

Bottom Line
If you believe the RV company or the tire manufacturer should be held responsible for the tire failure then you probably should file a complaint.
If you take a few minutes you might even decide the failure was not the fault of the tire company but of the RV company that selected a tire with no margin for any loss of air or load variation.
  You still need to provide tire information but in the last case of poor tire selection I would be sure to include statement with actual measured loads and the small reserve load the tire selected provided.

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"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.

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22.5 tire inspection. Confusing answer from dealer

Got this Private Message (PM) about sidewall "Bulges". Will keep it "private" redacting any identifying details but think there is a good learning experience for others here.

===========
 Thanks for sharing your knowledge, and I do like your blog!

I have 5 1/2 year old xxxxxxxxxxxx Mich XZE* tires on our coach. No cracking, and have performed well.

I found sidewall 'bumps' on two tires ("Tire store" Tire Center gent, said they're not 'bulges', as they're so slight). One maybe 3/32" of a protrusion, the other much less. The "tire store" gent said they could be belts that are misplaced or broken. But, he also said the "*" XZE's have a thicker sidewall, and that the outer layer of the tire could have separated.

I know it's hard to give advice based upon a description, but, I wanted to ask your thoughts on the opinion given to me by this "tire store" gent.

He suggested that I monitor the size of the 'bumps' daily, and if they don't grow, he felt that they were safe to drive on. When asked if he would drive on them with his family, he said from what he could see, yes. He commented that the tire was so overrated for what it was carrying weight wise on my RV, that it was not working hard.

I've always thought that once a tire starts to break down, that it was at risk for a catastrophic failure?

The tire was not unmounted for inspection, but if it was a outer layer separation as he said it could be, how would they be able to see this?

Opinion? At 5 1/2 years of age, is it worth even considering monitoring and watching for growth? Or just replace and move on?

(I have a thread on Class A, asking for ride opinions between the XZA2 and the Cont HSL1 in 315/80R size. These are the two I'm currently considering to put on the steers. But, open for input on others to consider too!)

Hope you don't mind the PM, but, I was just a bit uncertain on which way to go.

Best,
zzzzzzzzzzzzzzzz
=======================
Here are more pictures of the feature of concern. You can see the small bulge right above the "M"

Here is my reply
========================
First off I do not feel that sidewall "bumps", "bulges" or "protrusions" occur because of misplaced or broken belts. Belts are under the tread not on the sidewall so I have to wonder what training, if any, the "gent" at "tire store" has received on tire construction or inspection procedures. Also not sure what he is talking about as the "outer layer" of the sidewall. In a TBR tire there is basically the thin innerliner then the body ply then the sidewall. So if he thinks the sidewall has separated then the tire has failed and should be replaced.

Now some fact based observations on sidewall bulges or outward protrusion vs depressions that are inward toward the air chamber and are indications of two completely different causes.

The inward depressions can occur once or twice around almost any radial tire. If you take a close look if full sunlight of smooth sidewall tires you will see depressions than might be about 1/4" to 1/2" wide in the circumferential direction. These are caused by the lap splice of body ply material that provides more resistance to the slight growth seen in all radials due to inflation. The depressions will run a radial direction from the wheel to the tread and seem to dispensary as you get near the tread or near the wheel. These are normal and I would only consider them minor cosmetic features of a tire.
An outward bulge may be 1/2" or as large as a couple of inches in the circumferential direction. The larger or more distinct the more concerned I would be about the durability of the tire. Usually bulges are the result of some impact damage done to the body cords that resulted in a few being broken due to shock loading.

Here is a blog post I did with pictures to help people understand.

Here is a post on an Impact Failure I had on my personal car

Now some with small features the eye plays tricks as to it being a bulge out or a depression in.  I have even seen instances of two depressions being close together such that the normal sidewall between the depressions gave the appearance of being a depression. The simple tool to use is a ruler or straight edge and to lay it across the area of interest. This will quickly identify if you have a bulge or depression.

What to do:
Review my blog posts above.
You might also find a different dealer. A simple Google for "Truck Tire Dealer Town"  where "Town" is a near-by larger community, should give you a number of options.
Are you dealing with a TCI  "Passenger/Light truck center" or a "Commercial Truck Center"  For 19.5 and larger size tires I would only deal with a Heavy truck Center.
You might also contact Michelin at their Customer Contact identifies on their RV tire page for a suggested location with people sufficiently trained in tire inspection to pass judgment on your tires.
you can tell them that your not happy with the inspection you got from "tire store" as they don't seem to understand the basics of tuck tire construction.



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How to avoid tire failure and RV damage. And I had a tire failure!

A general comment on tire inspection and how it may be able to prevent RV damage due to tire failure if done properly.

There are three basic types of tire failures.

- The least likely is a sudden large impact with some object in the road. This is the least likely and is actually difficult to do. By this I mean to have a tire that is OK with no damage having been done due to excess heat, high load, low inflation or improper repair. It could even be a new tire. You drive over something like a Railroad spike or into a foot deep pot hole or over a 10" chunk of scrap steel that fell off a truck. It has to be large and you have to hit is just right for the tire to suffer immediate failure. I know from personal experience (doing a special test project of tire "Rapid Air Loss") that even driving over a piece of 2" pipe sharpened at one end and standing 2" up in the road with sharp end up doesn't always cut through the steel belts of a tire.  Yes you might run over something that cuts the tire but you would see it in the road and hear it hit but most of the time the air loss is not immediate. The good news about this type of failure is that it has a very low probability of happening. I would guess that fewer the 5% and maybe less than 2% of RV tire failures are of this type.

- Next is the belt separation. This is when the tire tread and belts come off the body of the tire. This is usually the result of tire aging and long term cumulative heat related damage that reduces the flexibility of the rubber to the point that rather than bending the rubber develops microscopic crack which do not heal themselves but will grow. Excess heat and tire aging can come from many sources. Even parking in direct sunlight with "tire protectant" spray does not lower the temperature of the tire. Excess heat can accelerate the aging or the tire rubber properties and drastically reduce the tire life. I would expect that if properly diagnosed this type of failure occurs 25 to 40% of the time. The good news is that with proper and frequent tire inspection this can be discovered and the tire replaced before it comes apart enough to cause damage to the RV. I did a blog post just on this topic "How do I inspect my tires" back in Aug 12 2014. You can Google the phrase and find a number of web pages on the topic but many simply are telling you to look at tread depth but this is not sufficient if you want to do a complete and competent inspection. My link included a YouTube video showing the inspection of a tire with belt detachment that has not come apart and the result of the "tire autopsy" I was able to perform. You can even see the separation between the belts in the above post.

- Finally there is what is commonly, and incorrectly, called a "Blowout". This is really a failure of the tire sidewall due to excessive flexing from running with significantly under-inflated ( probably below 50% of the inflation needed to carry the load. For Polyester tires (mainly ST and LT type) This heat due to flexing can be enough to reduce the strength by half and in extreme cases even melt the cord. For Steel body tires the bending of the steel can result in a fatigue failure similar to bending a steel paper clip till it breaks. This type of failure may be 60 to 80% of the failures on RVs. The good news is that if you run a TPMS you will get a warning of the air leak and hopefully you will not ignore the warning as too many do with other warning indicators on their dash, and take appropriate action which is to stop and pull over as soon as safely possible. Amazingly some people, even when verbally warned that they have a tire that is significantly under-inflated simply choose to continue to drive off. This has happened to me a number of times. As the saying goes "You can lead a horse to water but you can't make them drink".

So how doe this information help you "avoid" failure and RV damage. While nothing is 100% I bet you would like to be able to prevent 90% to maybe 98% of tire failures you might experience.

To do this I suggest that you run a TPMS and to get plenty of advance warning I suggest you set the warning pressure to be the minimum needed to support the load. Then your cold inflation pressure would be about 15% higher.

Next do a "free spin" inspection with lots of light. This is relatively easy with a trailer but harder to do as your axle load increases. You may even need the HD jack from a truck tire center and the spin balance machine to get that big 295/75R22.5 tire spinning at at least 20 to 30 RPM to allow you to see if there is "wobble" similar to the video in my post on How to I Inspect my tires" above. While the tire is in the air also do a slow rotation to inspect 360° of the tire tread as well as 360° of each sidewall looking for cuts and bulges. If any are found you should get the tire to a service center for a more thorough inspection that may include de-mounting the tire.

I believe that if you don't see any bulges or wobble and don't have any localized irregular wear spots in the tread you can be reasonable confident there is no large separation.

Remember nothing is 100% but if you make an effort you can significantly improve your odds of avoiding a tire failure.

Information to show you how this can work. Three weeks ago I was doing my annual 360° inspection. My tires are 7 years old so even though I know they have always been properly inflated (4 corner weights + TPMS from 2nd week of operation), I knew I needed to be sure all was OK. I discovered one of my duals had developed stress cracking from long term parking. This was a real surprise for me but it shows that even with the best of care rubber can get old and tires do need to be replaced.

  This tire was scrapped (I cut two slices from bead to tread to prevent its re-use by a "dumpster diver") as it still had lots of tread but I felt it should not be on the road.

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