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Old 09-02-2013, 11:18 AM   #15
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You forgot the 3rd and most important, the QUALITY of the tire.
Nope didn't forget Quality.
The reality is that all tires sold for highway use in the US must be certified by the tire mfg or importer that the meet all the regulatory requirements.
Now I know that the major tire companies take quality seriously and have most if not all of their manufacturing plants certified by independent auditors for meeting various standards such as QS9000 or ISO TS16949. I have never heard of an RV assembly plant meeting any similar standards and doubt if the low cost suppliers even know what these standards are never-mind pay them any attention.

The adjustment rate of most car tires is usually lower than 0.5% with many below 0.05%. Now this is based on actual forensic evaluation of the root cause of a failure and not the un-informed opinion of the consumer who has no training it tire engineering.

When the vast majority of tire failures can be traced to under-inflation, over-loading and excess heat which probably cause 80% 90% or more of the failures, why should I spend time on the quality of tires when people buy on price and not on quality or suitability for the purpose?

Many will simply claim that since a tire failed it must have been defective but I have never heard of a owner being able to point out the exact defect they claim caused the failure.

One problem with RV tires is that since the RV owners would rather simply complain around a campfire or on a forum than spend the few minutes it takes to file an actual complaint with NHTSA the numbers of failures reported do not raise any flags that more investigation is needed.
See my post of Dec 31, 2012 "How to file a complaint with NHTSA".

I can give an example. This weekend I identified an RV that was not in compliance with DOT regulations. Even though I offered to assist the RV owner to file a complaint with NHTSA that would probably trigger a recall, the owner just couldn't be bothered.

So are there lower quality tires our there? Certainly.
I did a post just on the topic "Why are bad tires on the road." on Jan 7, 2012

On March 22, 1013, I posted on the "Quality of complaints on Chinese made tires"


What I also know is that with over half of the RV on the road being overloaded, complaining about the quality of tires is not productive as long as RV manufacturers can't be bothered to provide tires with adequate load capacity and RV owners overload and under-inflate their tires.




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Old 09-02-2013, 12:09 PM   #16
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The factory could offer them as an option.
They could, but that would involve cost and inventory. I am sure some dealers do offer it as an option.

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Old 09-02-2013, 12:18 PM   #17
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One loosens the lug nuts and removes the wheel. Then the Centramatic disc is placed over the the wheel studs, usually with the ring facing the drum brake. Then the tire is placed back upon the wheel studs and the lug nuts are spun in until snug. Then a torque wrench is used to tighten the lug nuts incrementally in several passes up to the recommended torque value.

Re torque at 10, 25, 50, and 100 miles to ensure they lug nuts are seated.
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Old 09-02-2013, 02:37 PM   #18
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Tireman9,

Thanks for starting this discussion and offering your professional input based on your career in the tire industry. I think that it deserves standing based on those years in that profession.

CapriRacer,

Also thanks for your input also from your profession.

Airstream,

If the common knowledge is that the running gear provided needs to be balanced to prevent "shaken trailer syndrome" no one but your axle supplier is as suited to comply with that issue and nip it in the bud. Automated balancing of machined brake drums is not new.

Folks, I think this thread is best devoted to tire awareness to prevent unnecessary, costly and potentially dangerous tire failures.
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Old 09-02-2013, 03:15 PM   #19
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Tireman9,

Thanks for starting this discussion and offering your professional input based on your career in the tire industry. I think that it deserves standing based on those years in that profession.

CapriRacer,

Also thanks for your input also from your profession.

Airstream,

If the common knowledge is that the running gear provided needs to be balanced to prevent "shaken trailer syndrome" no one but your axle supplier is as suited to comply with that issue and nip it in the bud. Automated balancing of machined brake drums is not new.

Folks, I think this thread is best devoted to tire awareness to prevent unnecessary, costly and potentially dangerous tire failures.
I agree, but unfortunately, axle suppliers do not supply tires and wheels along with the axles.

So that takes it back to square one.

I did encourage Airstream to balance the running gear in production.

They indeed did that for about 2 months, in 1971, finding that it was too costly to do.

I feel that it's very encouraging for owners to have the running gear properly balanced, if they so choose, without have to go through a bunch of hoops, or to locate a qualified shop.

Many owners love to their own PM, and now, they can add "tire balancing" to their list.

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Old 09-02-2013, 03:39 PM   #20
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Airstream,

Automated balancing of machined brake drums is not new.
Above is referring to the assembly line process of machining brake drums.

Andy,

Balancing of replacement tires is owners responsibility, agreed. But starting with balanced drums, can't Airstream add that as a supplier specification? Then properly balanced tires take over.

Lets let this thread refocus on Tireman9's efforts to educate on tire issues. I've seen a few TT's on the side of the road studying how to get out of this mess. The last one was last Friday on I-95 a 5'er starting his weekend outing with a flat tire.
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Old 09-02-2013, 04:41 PM   #21
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Please understand, that none of this is a personal attack on anyone posting an opinion on this matter, only a desire to make sure that others have the opportunity to consider the facts or science surrounding dynamic balancing products. I am a degreed engineer who has researched this area, and I also have several years of balancing experience in automotive, aviation, and industrial settings.

"First, when a tire is not rolling, it is not generating any centrifugal force, so there is no balancing going on."

Answer: This is OK, no balancing is needed when the wheel assembly is not rotating.


"At what speed does the centrifugal force become enough to overcome the force of gravity to cause the balancing effect to dominate? I don't know, but it seems to me that since gravity never stops working, it is always a factor of some sort."

Answer: Gravity is a factor, however it is insignificant relative to the centrifugal force of the rolling wheel assembly. I am sure that you have twirled something weighted on the end of a string before. Gravity is at play, but the centrifugal force is much greater and allows the object you are twirling to move in any axis.


"Second, any separate piece that you mount on the wheel hub isn't doing any dynamic balancing. It's only doing static balancing in the plane it is operating."

Answer: This statement is incorrect. Any of the methods mentioned, Centramatics, balancing beads, balancing powders, are the very essence of dynamic balancing. They work just like the harmonic balancer on the crankshaft of your car. They automatically redistribute as a reaction to the tire moving in the opposite direction due to imbalance. Possibly the confusion is due to what some incorrectly call "Dynamic Balancing" where they take readings on a rotating assembly while it is rotating and then place weights on the assembly at locations determined by the balance machine. This is how we balance turbine engine rotating assemblies, helicopter rotors, and wheels and tires at the local shop. It is not truly dynamic balancing is more correctly called dynamic assessment of balance as it is only accurate for one single condition(rpm, condition of the assembly, etc) as soon as anything changes such as the tire wearing, or having a rock lodged in the tread, the balance is no longer accurate. Centramatics, bead, powders, do "dynamically" re-adjust to the changing conditions.


"And while "balance beads" are not constrained to operate in a single plane, I still have concerns about what they do to the insides of tires."

Answer: I respect the caution. I agree I have heard and read of many things that I would not do, and I would not just throw something inside of my tires without a lot of research. If you read the internet, some will suggest that golfballs, Airsoft Pellets, small pebbles, BB's will all do the same job. They will in fact balance the tires, but they will also possibly damage the insides of your tires. Dynabeads and Equal Powder are manufactured specifically for this purpose. They have been tested, and are widely accepted in the trucking industry with millions of miles to their credit. I have personally used them and have nothing but good things to report. And no, I don't have any financial interest in any of the products mentioned."


"And as a last thought: If these things were so good, wouldn't vehicle manufacturers install them in their factories? Think of all the warranty money to be saved - and all the dissatisfied customers they wouldn't have - if these things worked as advertised."

Answer: Follow the money.... who loses out if tires last longer....who loses out if they don't have to be rebalanced...... and last but not least, public skepticism. We don't often accept things we don't understand. It is hard to grasp that throwing some beads or powder inside the tire will "magically" balance the tire. Skepticism aside, it really does work. Here is a video that shows the principle DynaBeads demo video - YouTube


The only negative I have personally witnessed, is when you hit a really large pothole or anything that disturbs very significantly the dynamic balance will attempt to fix the problem, and then as things return to normal, you might feel a very slight imbalance for about a second as the dynamic system readjusts. I consider this to be minor compared to the almost continuos imbalance that occurs in normal static balancing.

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Old 09-02-2013, 05:09 PM   #22
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Dennis,

Thanks for the balancing info and you're explanations.

To all:
The original title and intent of this thread is Why Tires Fail.

I think that is the topic to be discussed, balancing would be better served as its own discussion and I think one exists currently.
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Old 09-03-2013, 04:11 AM   #23
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The Centramatics sure work well on my Honda GoldWing and we never even balance the tires with weights any more. By the time the bike is moving enough to stay upright, the wheels are balanced.

The up front $199 expense could be far less than the cost of repairs due to a vibration generated in the suspension system. Installing the best possible tires after being properly balanced means the Centramatics can compensate for the brake drum's out of balance state. If a wheel weight comes off due to a bump in the road or poor installation, the Centramatics can he keep the assembly balanced until the tire can be properly re-balanced.

YMMV
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Old 09-03-2013, 06:55 AM   #24
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First, I think the issue of balancing is a good one for debate. I also hope people won't get all caught up in defending their position that they lose civility. We can discuss these things without the need to get snotty or personal.

I also recognize that this thread is about tire failure - but since the subject has been brought up.......

Hub and rotors? If you'll look, you will find some that have grind marks or weights added. This is obviously there because they not only measure it for balance, but corrected the imbalance.

Here's an illustration:

http://www.barrystiretech.com/rotorbalancemark1.jpg

Look at the first entry on the right hand side.

And cost for a vehicle manufacturer? With the normal balancing methods, car manufacturers have to have balance machines, buy weights, and install them. This costs money, so it isn't as though it's free. - and while Centramatics are fairly expensive, balancing beads aren't. Don't they work on the same principle? So why do 100% of the car manufacturers chose to use weights?


But in all fairness, I think it has been demonstrated that Centramatics work to some extent. The video does show that the balance is better:

Centramatic Automatic Wheel Balancers Demonstration - YouTube

- but the video unintentionally shows they don't work as well as a balanced assembly. Note the bit of vibration of the little red tab below the tire.
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Old 09-03-2013, 07:33 AM   #25
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I am going to truncate the post because I only want to address certain statements.
Quote:
Originally Posted by rv4007 View Post
Please understand, that none of this is a personal attack on anyone posting an opinion on this matter........

Answer: Gravity is a factor, however it is insignificant relative to the centrifugal force of the rolling wheel assembly. I am sure that you have twirled something weighted on the end of a string before. Gravity is at play, but the centrifugal force is much greater and allows the object you are twirling to move in any axis......
And whenever I do twirl an object on a string, I do indeed feel the tug of the weight as it rotates - BUT - are my hands sensitive enough to note the effect gravity has? I don't think so.

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......Answer: This statement is incorrect. Any of the methods mentioned, Centramatics, balancing beads, balancing powders, are the very essence of dynamic balancing........
I think we have a difference in definition of the term "dynamic balancing". In some respects it would be more properly termed "2 plane balancing". This is not to be confused with "changing over time".

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......They work just like the harmonic balancer on the crankshaft of your car............
Ah ..... not exactly. Harmonic balancers aren't really balancers. They are dampers - of rotational speed variation and non-rotational movement. They dampen out the flexing caused by the firing of the cylinders and the pulses generated by the explosion.

Please note that internal combustion engines have balance weights on the crankshaft. Doesn't this say that this is the preferred method of balancing?

[QUOTE=rv4007;1348948]......This is how we balance turbine engine rotating assemblies, helicopter rotors, and wheels and tires at the local shop......[/QUOTE}

I note with great interest that in every case you cited, everyone is balancing with weights.

Quote:
Originally Posted by rv4007 View Post
......It is not truly dynamic balancing is more correctly called dynamic assessment of balance as it is only accurate for one single condition (rpm, condition of the assembly, etc)......
Ah .... not exactly.

First, you are right about the use of the term "dynamic" - as I explained above.

But the beauty of balancing using fixed weights is that it balances independent of rpm, and condition of the assembly. In other words, it takes what is there and deals with it and the balancing doesn't change regardless of the speed.

Now the need to balance an assembly to tighter tolerances is a function of speed, but we are talking the amount of allowable tolerance, not the principle itself.

Quote:
Originally Posted by rv4007 View Post
......Dynabeads and Equal Powder are manufactured specifically for this purpose. They have been tested, and are widely accepted in the trucking industry with millions of miles to their credit. I have personally used them and have nothing but good things to report. And no, I don't have any financial interest in any of the products mentioned." .....
And here is where our experiences differ.

Have I seen damage to the inside of tires due to a balancing compound? Yes!

Why? I suspect it is because there are so many tire manufacturers and each one has its own formula for the innerliner (the air retaining rubber on the inside of the tire). I just can not image that any of these balancing compound manufacturers have tested them all. The thing I can image is that there may be reports sent back to the balancing compound manufacturers - who may or may not make changes.

Quote:
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......Answer: Follow the money.... who loses out if tires last longer....who loses out if they don't have to be rebalanced......
I don't think this argument holds up as car manufacturers have to pay car dealers every time a new car has to be rebalanced. This is a cost to them, not a revenue stream.

Quote:
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......Dennis
Nevertheless, thanks, Dennis, for the discussion points.
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Old 09-03-2013, 08:18 AM   #26
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The owner of the trailer can do much to reduce early tire failure if they so choose.

1. Cover tires with a light colored cover when the unit is stationary.
2. Check and keep tire pressure at correct psi.
3. Have new tires spin balanced before installation.
4. Rotate and balance the tires perhaps every 5,000 miles.
5. Use an infrared temperature reading device at every stop and check both wheel bearing covers and tire sidewalls on both TV and TT. Check more carefully any tire or bearing with a major temperature deviation.
6. Inspect tread for any inbedded glass, rocks or metal before any trip and when at destination.
7. Raise side of trailer and place a stone, brick, or board near tire tread and slowly rotate tire to see if it is out of round.
8. Check both side walls of tire for any damage or unusual sidewall deformation.
9. If funds allow, install a tire TPMS system for early warning of an impending tire issue.
10. Consider installing a device like the Centramatics or balancing beads to help balance the entire tire,wheel and hub (or rotor if disk brakes) assembly.
11. By judicious use of the scales, ensure that no one tire is overloaded on any one axle even though the total of the two tires seems correct when weighed together.
12. Respect the concept of a three (or four year max) year service life despite the mileage.

I am sure more suggestions could be added to the list, but an ounce of prevention is worth a pound of cure (especially in the UK).
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Old 09-03-2013, 08:33 AM   #27
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Quote:
Originally Posted by CapriRacer View Post
First, I think the issue of balancing is a good one for debate. I also hope people won't get all caught up in defending their position that they lose civility. We can discuss these things without the need to get snotty or personal.

I also recognize that this thread is about tire failure - but since the subject has been brought up.......

But in all fairness, I think it has been demonstrated that Centramatics work to some extent. The video does show that the balance is better:

Centramatic Automatic Wheel Balancers Demonstration - YouTube

- but the video unintentionally shows they don't work as well as a balanced assembly. Note the bit of vibration of the little red tab below the tire.
Yes indeed, the model shows a little vibration.

Please note, that the tire size is only about 8 inches.

The operators hand is about half the size of the tire.

There are many causes of tire failures.

Lack of proper balancing, is just one of them.

Andy
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Old 09-03-2013, 09:22 AM   #28
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Heat and Under-Inflation

Switz did a great job of summarizing the various issues. One caution, most manufacturers of beads or powder recommend removing the lead weights before installation of the beads or powder.

I owned two businesses that between the two of them had 50-60 tires on the ground at all times (heavy trucks, trailers, heavy equipment). Our failures were almost exclusively on the trailers and were almost exclusively due to under-inflation compounded by heat buildup due to road surface temperature and speed. The typical scenario was to puncture a tire in a landfill or in the woods and develop a slow leak which was not noticed during pre-trip inspection. If the trailer were heavily loaded, then a blowout was common. Drivers who commonly drove below 55mph on country roads had fewer blow-outs than drivers who were on the interstate at 65-70mph. We had more blowouts in summer than in winter. Heat damage to a tire is cumulative, so even if the blowout did not occur on that trip, that particular tire would likely fail at a later date.

Many Airstreams are running at or near the rated tire loading, so their are similarities to my experiences above. The primary difference was that the blowouts did not damage my equipment trailers the way they typically damage travel trailers.

I have never had a tire failure that could be attributed to imbalance. I have replaced tires before their normal life expectancy due to tread damage caused by imbalance, but no failures.

If one is primarily concerned with tire failure I would focus on inflation and loading. Since we don't normally notice under-inflation until it is too late, I think a TPMS is a wise investment.

Dennis
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