Change your own tire ?

For my Class-C  I have a bottle jack with a rating greater than GAWR of rear axle. Since I would only jack one side that gives me plenty of lifting power. It's also easier to jack while laying on the ground.😥

Harbor freight has good deals.
An important item is a large flat plate to support the jack if not on concrete.
Maybe 12" x 12" 1/4" thick steel plate or 2" wood but you might still need a 6"x6" 1/4 steel so you don't split the wood.  Check with local shop offering welding or tow hitch install as they many times have scrap pieces available.

If jacking, be sure to set brake and block the tires front & back so the RV can't roll.

Whenever I change an outer dual I run a couple lug nuts on the inner (hand tight is good enough) as soon as I remove the outer, just to keep one wheel under the coach in case something slips with the jack.
If changing the inner dual I temporarily use the outer tire as safety backup.

IF YOU RUN 19.5 or 22.5 tires
I strongly suggest you get a service truck and let them wrestle the 150#+ tire and wheel around.

Also it is important to remember if you have lost more than 20% of your air in any tire it is considered flat and if you drove any distance on it you may have damaged the body and it could explode when re-inflated.  Inform the tech and let them inspect and re-inflate or replace. This could result in injury or worse.



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##RVT800

Understanding Tire Failure

Yes, when a tire fails there is almost always evidence left behind that points to the Root Cause. I have shown this in tire "autopsy" posts on my blog.

Some "causes" are easy to see or understand:
Punctures, cuts and external damage from hitting potholes or other "road trash" can lead to leaking air (fast or slow) or in some cases broken body cord (see my blog post on sidewall bulges).

"Blowouts" with sidewall flex failures are most likely the result of air leak, not just low air pressure due to poor maintenance. The leak could be caused by puncture, cut, leaking valve, cracked wheel or the like.


Other failure modes are harder to detect, such as:

Belt separations come from long-term heating of the tire belt/body interface. This heating comes from a combination of insufficient air pressure for the load and excessive speed.

Now while separations may be harder to detect, many can be found if a little effort is made by the person doing the tire inspection.

I previously published a video showing one way to "measure" a defect.

Sometimes you don't need to "spin" or rotate the tire but just get a good look at it and roll it across the floor for a full revolution as one part may look OK while another portion clearly would only look straight to a drunk.

If any of your tires look like the above, I would bet $$ that they had a belt separation similar to what is seen here.

Driving on a tire in this condition is simply asking for trouble as it could come apart when you least expect it as you drive down the road.

As we move out of Winter and you "DE-Winterize" your RV, especially trailers, Please take the time to do a thorough tire inspection.  Spin or off-the-vehicle inspection is much better than a stationary on-the-vehicle "Look At".




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Why do tires fail?

Some comments on the general question of tire failures and why they seem to be so prevalent on RVs.

Previously I posted on how tires may be selected by the RV manufacturer. Lowest cost with the least margin of safety allowed by law seems to be the general trend for many manufacturers. We also know that well over half of all RVs that even bother to get weighed have one or more tires overloaded. These facts seem to be something that many want to ignore. Many blame the geographic location i.e. China where the tires were manufactured as the cause of the failures. Some think that the tire mfg intentionally makes poor quality tires. The fact is that tires do not fail for no reason at all. They do not fail because the factory was painted green instead of blue. They fail because their finite life is used up or they suffer some external damage or puncture which lets the air out. Punctures are not always obvious as this one with a 6" piece of aluminum from a broken truck rim poking through the tread.

Some punctures are quite small. So small that you need magnification to see them.

 This puncture resulted a 2 psi per week leak and I only found it after noticing the very slow air loss and the need to add air every week to 10 days.

Impacts do not always result in immediate loss of air. Some tires can run for many miles, days or even weeks and still might not “Blowout”.

 Can you honestly remember every pot hole or curb or piece of road trash you ran over in the last 10 or 20 miles or yesterday or 5 days ago as you pulled into the campground?

 

Valves can fail because the rubber components age-out just like tires can but how often have you replaced the rubber gasket in your metal valves? Do you even have bolt in valves? Standard “snap-in” valves are rated 60 psi Max but since they don’t come out of the wheel immediately after you inflate your tire to 65 psi how many owners assume all is OK for the next 5 years and 40,000 miles?

Valve cores can develop slow leaks if a single grain of sand gets lodged in the valve core seal. How many make sure they have a good o-ring in their metal valve caps, or do they simply use the cheap plastic caps as seen on most cars?

Tires age out. This does not mean that they will fail after 2782 days. It means that after sufficient time has elapsed at elevated operating temperature (which accelerates the aging process in a non-linear and ever increasing rate as the temperature goes up) the strength and elastic properties of the rubber degrade to the point that microscopic cracks that start out tearing molecular bonds apart, grow. The cracks never get smaller. They only grow. The rate at which they grow also depends on the physical properties of the rubber and the properties change with the temperature. Once the cracks grow sufficiently large, the structure starts to lose its ability to retain its integrity and things start to come apart in an ever accelerating manner.

I personally have run tests where I exceeded design range for load and inflation. The tires did not fail for 18 days when the load, inflation, speed and temperature were controlled in a laboratory. This test is repeatable so this is not magic. It is sound science. How many people would relate a sudden tire “Blow-Out” with conditions established 18 days previous?

 I do not intend my comments to mean that there has never been a tire failure that was caused by a manufacturing defect. What I want to show is that simply because you do not find a railroad spike lodged in your tire does not mean there was no reason for the failure due to external causes. It takes years of experience and sometimes hours of detailed examination sometimes including chemical analysis, X-Ray and even Electron Microscope examination to find the real reason for the failure. I know of no tire dealership that has any such equipment or that has provided man-weeks of training in forensic analysis to any of their employees that would allow them to arrive at the real answer of whay a given tire failed.

Tire Failure because "Made in xxxxx"

In my training class for tire engineers and technicians, a concept I feel is important is discovering the "Root Cause" or real reason for the failure. There is difference between reporting or simply stating the condition of a tire such as "a Blowout" and the reason for the condition. If you don't understand the underlying reason for the tire's condition or what initiated the series of events that led to the failure, then the corrective action you take, may not prevent another failure.

If we are confronted with a tire that looks like this
many would simply say "we had a blowout". If they then read the information on the tire sidewall that says "Made in xxxxx"  or if they read the DOT serial and used the information on THIS website to learn where the manufacturing plant was located they might simply claim the tire failed because it was made in country xyz. They then simply jump to the conclusion that the way to prevent having a similar failure in the future would be to only buy tires not made in the same country the failed tire was from. They might feel better but in all probability they will not have taken the appropriate action to lessen the chance of having another failure as the country of origin in itself, is no more likely to have "caused" the failure than would the fact that the tire plant was painted blue rather than green.

Lets step back and look for physical evidence for the real reason or "Root Cause" for the failure. A simple trick is to ask WHY? at least 5 times. Here is how it works in the case of this failure.
1. Why did the tire fail? Answers might be the sidewall shredded or the tread and belts came off or there is a large bulge in the sidewall or because there is a nail or other puncturing object in it etc. Each of these answers would generate a different 2nd question
2. Why did the sidewall shred? Answers might be: Possibly hit a pot hole or tire was driven on after it lost air.
3. Why can you know if you drove on it after it lost air? Answer It would have melted body cord or fatigued steel body cord
4. Why did you drive on the tire after it lost air?  Answer might be: I didn't know it was leaking
5. Why did the tire leak? or Why didn't you know the tire had lost air?  Answer might be: The valve failed or I had no Tire Pressure Monitor System.
Now you have enough information to take the appropriate action as simply changing brands of tires will not stop the valve from leaking or give you warning of an air loss due to puncture in the future.

Now to help you out with understanding what evidence can help you ask the correct questions I will offer a few examples of various conditions.

Tire puncture large and obvious

Tire puncture small and hard to find

Melted polyester body cord only occurs when tire structure temperature exceeds 375° F

Steel body ply fatigues along the line of greatest bending sometimes resulting in a "zipper"

Steel fails (think paper clip) when bent back and forth more than it was designed to for many cycles. You can see this "necking" with a low level magnifying glass.

I hope this helps you understand that it is very difficult to stand back 10 feet and look at a tire and know why it really failed. I also hope that you have a better appreciation for the fact that if you don't investigate and learn the real reason for the failure simply changing the tire brand may not prevent another occurrence.

Bottom Line
If you have a failure you need to preserve as much of the evidence as possible so either you or the tire dealer you work with can do a more thorough "autopsy" to learn the real reason for the failure. If the tire is under warranty, the dealer or manufacturer will want to be able to examine the failed tire. It is unrealistic to expect compensation for a failed tire without you being able to provide the evidence of the failure. The major manufacturers have teams of engineers who's job it is is to inspect failed tires so appropriate action can be taken. This is why I suggest that you buy your tires from a large tire company with thousands of stores rather than buy the cheapest tire you can find at "Billy-Jo-Bob's Bate Shop & Cheap Tire Emporium" .

What is involved in doing a tire inspection?

 Some of you may wonder how I can provide an opinion on what caused a tire to come apart when all I see is a picture or two. 

For many decades my primary job was to perform tire inspections and "autopsies." I estimate I did more than 20,000 inspections, so I was able to build a good experience base for my observations.

My findings were many times presented to a customer that did not want to accept responsibility for the failure, so I needed to be very thorough and to provide an easy to follow explanation.

 Here is an example of just one such inspection.

The tire was reported to have "blown out on a local road” The lack of facts and data did not help in the analysis of the tire.

However I was able to establish that the tire suffered a sidewall puncture, lost air and after running significantly under inflated at highway speeds for a number of miles the cumulative damage to the tire resulted in a flex fatigue failure.

Photo -1 above

                Shows the 2 piece condition, which is indicative of, flex fatigue failure.

Photo -2

Shows the result of melted body cord – Body Cord melts at 350°F to 400°F

Photo Tire-3

Shows the abrasion on the interior from running a few miles at essentially zero inflation

 Photo 4 shows a larger portion of the interior. Here I noticed the location of a possible small sidewall puncture.

 

Picture 5 is a close-up of the area of interest

  

 Picture 6 is what the outside looks like.

The question is ... How do I prove there was a puncture?  If I used a sharp probe like an awl some would think I might fave made the "puncture" myself. Over the years I learned a trick. If you take a paper clip and straighten it out, you can use it like a probe. The un-bent clip isn't strong enough to hold and doesn't allow you to force the end of the clip through the sidewall of a tire but if there already is a hole, the paper clip can be guided through the already made puncture.

Pictures 7 shows the clip on the inside

Picture 8 shows the clip on the outside at the suspect location.

               

Findings

                The tire was not defective but failed due to being operated significantly under inflated. The under inflation was caused by the small sidewall puncture.

Corrective Action:

                Use a TPMS. Instruct driver to be more attuned to ride & handling degradation, as this tire should be operated with 80 psi under normal conditions. A slow leak would have taken some time and resulted in significant changes in handling and vehicle response.

BOTTOM LINE

Some punctures are hard to find. Sometimes the puncture occurred in the heavily damaged portion of the tire so it is impossible to demonstrate the puncture. Melted polyester body cord is physical proof that a tire was run with only 10% to 20% of the proper inflation.

A Tire Autopsy "Root Cause" Part 1

Many  people make statements about a tire "blowing out" or being defective but few post any facts about the real condition of the tire other than it came apart. There is a major difference between simply reporting a condition and providing information on the "Root Cause".
Examples of Conditions would be "the tread came off' or "tire lost air" or "tire went BOOM".
Examples of Root Cause might be "tire had a puncture" or "tire had an impact break" or "tire was run low and the sidewall had a flex failure". If you don't know the "WHY" of a tire failure then whatever actions were taken after the failure may or may not help to prevent a re-occurrence.

To help you understand this concept I want to take you through some real life examples. In many of these examples it was initially claimed that the subject tire was simply "defective" however as we review these examples I think you will ultimately agree that most tire failures occur because of some outside cause.

Here are three examples of damage done through the use of a high pressure power washer.

In each case someone claimed there was a defect built into the tire that caused a blister to form as seen in the pictures.

I know and proved that the damage was in fact caused by the use of a power washer as I did a quick cut tire examination (autopsy) to examine the layers of the sidewall. No internal contamination was observed.

A theory was formed and an experiment done to confirm or refute the theory. A tire that was sound was selected and using a pressure washer similar to what any of us could buy at a big box hardware store, we were was able to duplicate this damage.

Sidewall Impact Breaks occur under a combination of variables that have a very complex interaction. These include speed, load, inflation, shape and size of the item impacting the tire, angle of impact and even the condition of the shock absorbers. Change one or more of these and you may avoid the damage.

What usually happens is the pot hole or road debris is hit but if the tire doesn't immediately fail the incident is forgotten. Miles later the now damaged and weakened sidewall ruptures with no advance warning. Even if you have a TPMS you will probably get only a few seconds advance warning as the now hot rubber will rupture very quickly and the tire will many times shred which destroys the evidence.

Sometimes the sidewall bulge is observed before the sidewall ruptures. The inspection of tires with this body ply damage allows us to identify the sequense of events. In fact if you attend one of my tire seminars I relate the story of my then fiance and her experience of traveling over 17 miles after the impact before the tire ruptured.

Next time I will cover Belt Detachments

                      and Punctures

Why Do Tires fail #2

We need to have a better understanding why tires fail if we are to prevent or decrease the probability of another failure occurring in the future.

In the first post of this series, I said we need eliminate punctures or impacts when we investigate a claim of "defective" tire, as these external forms of damage have little or nothing to do with tire design or manufacturing process.
Some punctures are easy to identify.

This puncture was made by a piece of aluminum which based on its shape appears to be a piece of an aluminum rim from a broken truck rim.

Or when a chunk of wood goes right through the steel belts





Or small piece of metal








Now the above examples are relatively easy to find but here is something I found only by learning that the tire was loosing about 3 psi a week


This appeared to be a piece of steel like a straight pin that was only 0.01” diameter. If I hadn’t been checking my tires frequently (before I had TPMS on my car) I would not have know I had a puncture or was losing air. I could have suffered a run low failure.

Some externally caused damage is not found till someone takes a closer look




here is a puncture that caused a slow leak but in this case the owner probably just kept adding a little air each week rather than pay to have it properly fixed. In this case the sidewall did not flex enough to melt the cord but the tire did run hotter than normal for many miles. This extra heat degraded the rubber which ultimately resulted in a loss of enough strength that the belts detached from the body.



In this case the initial inspector decided the tire was defective. However I think you will agree that a tire being punctures and the owner not repairing the puncture was the real reason the belts came off the body of this tire and not the fact that the tire was built in &X%*$ or the tire builder spoke in C*!%@@+.

Impact damage can be masked by subsequent damage but here are a couple examples.
Looking at the interior of this tire

shows that this impact was so severe the bead area of the interior of the tire (right side) was folded enough to rub against the interior under the tread.

In this case the impact broke a number of body cords in the sidewall due to the sudden impact.

I hope I have shown that failed tire analysis takes a detailed inspection if you are going to learn if the tire suffered external damage or had some other cause for the failure.

Why do tires fail?

Simple question but as with almost every question about tires, the answer is not a one liner. Stick with this post. It's not short but it really isn't technical and I'm sure every reader will understand the concepts.

When looking at why tires fail we need to first exclude the obvious damage caused by external objects i.e. pot holes, curbs, chunks of metal, glass or rock or other trash and junk on the road. Second we'll exclude broken valve bodies, leaky valve cores, valve gaskets, extension hoses, and cracked rims.

What's left will be a structural failure which would almost 100 percent of the time will be a detachment of different parts or components of a tire one from the other.

Most tires are made up of 20 to 30 different components such as different steels (belts and bead are not the same steel) textiles such as Nylon, Polyester, Rayon, Aramid. Then there are the various different rubber components such as Tread, Sidewall, Innerliner, Steel skim, Wedge, Flippers, Chaffer, base tread, Inserts, and other bits and pieces.


Each component is selected for different reasons and contributes both advantages and disadvantages to the total. Each component must "stick" to its neighbors both in the un-cured and cured state. The interface between two different components is weaker than the individual components but it must hold together through millions of cycles over a 200 degree temperature range.

All would be just fine if a tire were made completely of inorganic materials such as metals, stone or even ceramics. There are numerous formulas for the strength and fatigue limits for these inorganic materials.

The issue with organics (wood, rubber or other materials made from oil such as plastics) is that their strength has a "T" or time function. If you build a bridge of stone, you can calculate the maximum load it can sustain and as long as the structure isn’t changed due to external damage its strength will be the same the day it’s built and 50 years later. If I build a pressure vessel of steel and put 150 psi in it and it doesn’t fail I would have every expectation for it to continue to hold that pressure for decades, again excluding external damage.

However, if I build a pressure vessel of organic materials (a tire) it might hold 150 psi the first day or maybe the first few days but at some point it can fail. This principle is not something many engineers think of today because they don’t design bridges of wood but 100 or 150 years ago when wood was common they learned that a bridge that was strong enough to hold a railroad train to drive across, it could fail if the train parked on the bridge.

I educated some fellow tire engineers about this “T” function when I proved, through lab experiments that it was possible to fail a tire with high pressure above its stated max 18 days after it was initially inflated.

The other condition that affects and changes the “T” in the equation is temperature. Organics experience constant change (loss) in properties as the temperature increases. The rate of change (aging) doubles about every 20 degrees of increase in temperature, so it's not easy to calculate or predict the time it will take for an organic structure to fail unless you can control the temperature over time.

Bottom line. It’s a combination of temperature (heat) and time that causes tires to fail. A tire that spends its life in Flagstaff, Ariz., could last twice as long as a tire that spent its life in Phoenix if all other operating conditions were identical.

As the owner of an RV you can significantly affect one factor and that is the heat generated internal to the tire. When you run fast or overloaded or under-inflated you are running hotter. This means you are speeding up the rate of "aging" of your tires and can expect to see a tire fail before it wears out.