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Old 09-01-2013, 10:18 PM   #1
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Why tires fail

There are basically two reasons tires fail.
1. Over-load / under-inflation which are closely related since it is the inflation air that carries the load not the tire.
Under-inflation. A tire operating at less than 80% of the inflation needed to carry the load is considered to have been run flat and there is a good chance that there has been permanent internal structural done to the tire. Related to this is having the tire inflated to a level that just barely is rated for the actual load on the tire. Obviously you can be under-inflated because of cut or puncture or a valve leak or if you use an inaccurate gauge. If you run sufficiently low in pressure at highway speeds for a couple miles you can have a Run Low Flex Failure or more commonly a "Blowout".
Over-loaded Few people realize that by design most passenger vehicles have 13% to 20% or more "Reserve Load". That means that they are actually underloaded by that much for a vast majority of the time. Most TT on the other hand have tires selected that are at the tire max load and can just barely carry the actual load.
Data on actual loads measured on TT shows that over half of RVs measured (out of many thousands) have one or more tires overloaded based on actual inspection.

2. Heat. Heat damage occurs at the molecular level in that the ability of rubber to flex and stretch and not break the chemical bonds. Once broken these bonds no nor repair themselves, they just continue to grow. If they grow enough you can see the cracks and eventually you may have components come apart. Heat comes from a few different sources. This heat is generated by the flexing of the tire with the hottest region being at the belt edges (edge of the tread) in radials. Increased speed generates more heat and sometimes faster than the heat can be transferred to the surrounding air. Over-loading generates more heat. Under-inflation generates more heat. Having 0% reserve load generates more heat than having even 10% reserve load. Heat also comes from being in the sun. This heat can soak into the structure of the tire and actually accelerate the aging of the rubber in the tire. As rubber ages, it looses it's flexibility so this contributes to the breakdown of the rubber at the molecular level mentioned above. For every 18F increase in temperature the rate of aging doubles. So if the RV is parked with tires in direct sunlight you can see the tire achieve 36F increase or more which means it is aging at four times the rate it would have if in full shade. I have a blog post showing the results of a test of white tire covers to protect tires almost completely from this heat damage. Many times the cumulative damage from excess heat can result in a separation of the belts and tread from the rest of the tire.

Hope this helps others understand the primary causes of tire failures.
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Old 09-01-2013, 11:27 PM   #2
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I just sent you an email, but on second thought I think your response would be better placed on the forum. So here's my question:
So what is your opinion on tire balancing beads vs centromatics vs dynamic balancing vs whatever?
I'm looking at installing counteract beads, but I'm still researching.



thank you
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Old 09-02-2013, 06:46 AM   #3
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Quote:
Originally Posted by DryFly View Post
I just sent you an email, but on second thought I think your response would be better placed on the forum. So here's my question:
So what is your opinion on tire balancing beads vs centromatics vs dynamic balancing vs whatever?
I'm looking at installing counteract beads, but I'm still researching.



thank you
I am not a fan of anything except traditional balancing methods.

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

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.

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.

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.
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Old 09-02-2013, 07:04 AM   #4
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Quote:
Originally Posted by CapriRacer View Post
I am not a fan of anything except traditional balancing methods.

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.
Manufacturers don't want to spend money that the feel they don't need to.

Balancing running gear is a PM matter, not a manufacturers issue.

Tens of thousands of Centramatic owners are far more than satisfied with their balancers.

I am not aware of one single complaint against the Centramatic brand of balancers.

Many owners have expressed satisfaction with them due to noticeable improvements.

Many of them have so expressed that fact on this Forums.

Andy
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Old 09-02-2013, 09:20 AM   #5
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Quote:
Originally Posted by CapriRacer View Post
I am not a fan of anything except traditional balancing methods.

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

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.

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.

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.
Cost and profit margins. They quite often underestimate warranty costs. Besides balancing is preventive maintenance and NOT covered under most warranties.

Aaron
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Old 09-02-2013, 09:54 AM   #6
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Quote:
Originally Posted by Tireman9 View Post
There are basically two reasons tires fail.
1. Over-load / under-inflation which are closely related since it is the inflation air that carries the load not the tire.
Under-inflation. A tire operating at less than 80% of the inflation needed to carry the load is considered to have been run flat and there is a good chance that there has been permanent internal structural done to the tire. Related to this is having the tire inflated to a level that just barely is rated for the actual load on the tire. Obviously you can be under-inflated because of cut or puncture or a valve leak or if you use an inaccurate gauge. If you run sufficiently low in pressure at highway speeds for a couple miles you can have a Run Low Flex Failure or more commonly a "Blowout".
Over-loaded Few people realize that by design most passenger vehicles have 13% to 20% or more "Reserve Load". That means that they are actually underloaded by that much for a vast majority of the time. Most TT on the other hand have tires selected that are at the tire max load and can just barely carry the actual load.
Data on actual loads measured on TT shows that over half of RVs measured (out of many thousands) have one or more tires overloaded based on actual inspection.

2. Heat. Heat damage occurs at the molecular level in that the ability of rubber to flex and stretch and not break the chemical bonds. Once broken these bonds no nor repair themselves, they just continue to grow. If they grow enough you can see the cracks and eventually you may have components come apart. Heat comes from a few different sources. This heat is generated by the flexing of the tire with the hottest region being at the belt edges (edge of the tread) in radials. Increased speed generates more heat and sometimes faster than the heat can be transferred to the surrounding air. Over-loading generates more heat. Under-inflation generates more heat. Having 0% reserve load generates more heat than having even 10% reserve load. Heat also comes from being in the sun. This heat can soak into the structure of the tire and actually accelerate the aging of the rubber in the tire. As rubber ages, it looses it's flexibility so this contributes to the breakdown of the rubber at the molecular level mentioned above. For every 18F increase in temperature the rate of aging doubles. So if the RV is parked with tires in direct sunlight you can see the tire achieve 36F increase or more which means it is aging at four times the rate it would have if in full shade. I have a blog post showing the results of a test of white tire covers to protect tires almost completely from this heat damage. Many times the cumulative damage from excess heat can result in a separation of the belts and tread from the rest of the tire.

Hope this helps others understand the primary causes of tire failures.
You forgot the 3rd and most important, the QUALITY of the tire.
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Old 09-02-2013, 09:55 AM   #7
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Quote:
Originally Posted by wahoonc View Post
Cost and profit margins. They quite often underestimate warranty costs. Besides balancing is preventive maintenance and NOT covered under most warranties.

Aaron
The factory could offer them as an option.
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Old 09-02-2013, 10:17 AM   #8
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Do they install under the tire on the bolt pattern as easy as changing a tire or do you have to have them professionally installed?
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Old 09-02-2013, 10:25 AM   #9
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Do they install under the tire on the bolt pattern as easy as changing a tire or do you have to have them professionally installed?
Remove the wheel, slip the Centramatic's on the studs, remount the wheel.

Done.

Different models are available.

They are available for steel wheels, and for some Mag wheels.

The back side of the wheel must have a flat surface to some degree, so that the balancer is not damaged.

There is zero problems with the steel wheels.

Soon as the speed gets to 25 mph, they do their job. Also they continuously change in time, to compensate for tire wear.

Andy
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Old 09-02-2013, 10:36 AM   #10
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Quote:
Originally Posted by CapriRacer View Post
I am not a fan of anything except traditional balancing methods.

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

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.

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.

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.

I agree with CapriRacer on balancing. Wheel weights is all I have ever used on cars, trucks, trailers and even race cars.
Isn't it funny how engineers that trust data more than marketing hype so they usually share the same conclusions?
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Old 09-02-2013, 10:51 AM   #11
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Sorry but I disagree with both Inland RV Center and wahoonc on warrantee issues.
Car manufactures, you know vehicle manufactures that have real warranties of 3 to 5 years on 100% of the vehicle unlike any RV manufacturer I have heard of, really take warranty costs seriously. Vehicle ride is a very serious issue for cars and the cost of a ride complaint can be significant to the manufacturer. This is why there are balance specs on wheels and tires BEFORE they are mounted and every single tire is checked for balance before delivery to the mounting facility then checked again after mounting before shipped to the assembly plant.
Of course if you are buying tires based on cost and have no real engineers on staff or have a vehicle dynamics evaluation quality system in place then you probably figure you can cut corners and simply tell your customers vehicle ride and tire balance are "not your job" as an RV assembly plant

I am not saying the stuff poured into a tire is bad or does not provide some level of improved ride but some materials can damage the inside of a tire and others can void tire warranties.

If you want to use these materials rather than testing with a on-vehicle spin balance which will balance the tire, wheel and brake hub, then just be sure whoever is selling the alternate balance system will give you a warranty in writing that they will cover any damage to the tire and the use of their product will not void a wheel or tire warranty.
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Old 09-02-2013, 10:55 AM   #12
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Road Force the tires...Centramatics for the rolling assembly, piece of mind when you toss a weight.

Nothing but correct psi in the tire.

If you decide not to use them, so be it.

I'm not an engineer but I play one in the shower.

Bob
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Old 09-02-2013, 10:57 AM   #13
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Quote:
Originally Posted by Tireman9 View Post
I agree with CapriRacer on balancing. Wheel weights is all I have ever used on cars, trucks, trailers and even race cars.
Isn't it funny how engineers that trust data more than marketing hype so they usually share the same conclusions?
Balancing auto and truck tires, is very easy.

Thousands upon thousands of places do it, but they don't balance the hub and drum, or rotors..

Not so for RV'S.

The hub and drums usually used on RV's, are much heavier than cars.

They are machined these days, but never were not to long ago.

To find a shop that could properly balance a tire, wheel, and hub and drum as an assembly, has always been very difficult.

Spinning that assembly on the trailer, carries some danger, therefore is not done.

Removing the assembly, and using the old "Snap On Tool balancer" did work ok, but for a maximum of 10,000 miles.

Fixed lead weights have never compensated for tire wear as the miles on them accumulate.

That then brings up the question, of "how" can I long term have the running gear balanced, AND that stays in balance?

Centramatics solve that issue and without any inconvenience to the owner.

The advantages of using Centramatics far far outweigh the lead weight method of balancing.

They save time, save money, save tires, and having to chase down a shop to do the "complete" balancing, and save many damages to an RV, especially an Airstream, when the running gear is not balanced correctly.

Perhaps updating your theory might change your mind.

Andy
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Old 09-02-2013, 11:09 AM   #14
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Quote:
Originally Posted by Tireman9 View Post
Sorry but I disagree with both Inland RV Center and wahoonc on warrantee issues.
I am not saying the stuff poured into a tire is bad or does not provide some level of improved ride but some materials can damage the inside of a tire and others can void tire warranties.

If you want to use these materials rather than testing with a on-vehicle spin balance which will balance the tire, wheel and brake hub, then just be sure whoever is selling the alternate balance system will give you a warranty in writing that they will cover any damage to the tire and the use of their product will not void a wheel or tire warranty.
Who, offers a warranty on lead weight balancing?

Or for that matter, issues a written warrant that the wieghts "WILL NOT" fall off and the balancing, without exception, lasts X miles.

Many theory's about many things, in their days, were great, including tire balancing.

By today's advancement in Physics and simple running gear balancing, the old methods are outdated, and totally useless for the long term.

Any balancer that out lasts the tires life, is not even in the same class as lead weight balancing, especially when it comes to RV's.

But, as always the decision rests with the owners.

Centramatic owners have never, ever, stated any complaints, but most of them, have complained about the lead weight issues, from many stand points.

Progress is extremely important to most Airstream owners, at least based on my 47 plus years of working with them and finding many ways for them to better enjoy AIRSTREAMING!

Andy
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