Sorry but I am still confused about tires

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Thanks!!!!!

The op titled this thread "Sorry but I am still confused about tires " . I hope this all helps. As posted above there are axle ratings, vehicle ratings, tire ratings, hitch ratings and then there are actual numbers. All of this plays into selecting the tire that works for your situation.

It ain't like a passenger car.

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[ROBERT CROSS]

"3500+3500=7000(axle capacity)+800(tongue weight)-300(WD shifted back to axles)=7500lbs"

Why tongue weight?

Our TW is 1200lbs with 160lbs being transferred to the trailer axles.


All I'm saying...
4000lb axles would certainly improve the CCC, and supply a little more POM.

Bob

[Wazbro]

From Your RV Lifestyle.
RV and Vehicle Weight Definitions

GTW (Gross Trailer Weight), often used in towable RV applications, this is the same concept as GVW. Gross Trailer Weight, including tongue load or king pin weight, is measured by putting the trailer on a scale.

From the Boat Trailer Manufacturers Association.
Trailer Manufacturers Association - Frequently Asked Questions (FAQ's) - Answered by Dick Klein

GVW is the “Gross Vehicle Weight”, which is the actual weight of the vehicle. GVWR is the “Gross Vehicle Weight Rating”, and is the maximum allowable weight for the vehicle, which includes the weight of the trailer and the weight of the anticipated cargo. The axles must be able to support the GVWR, less the amount of weight carried by the tow vehicle (the “tongue weight” or the “hitch load”). This means that the GAWR (Gross Axle Weight Rating) may be less than the GVWR. It is generally accepted that this difference may be as high as 15% of the GVWR for bumper pull trailers, and 25% for gooseneck and 5th wheel trailers, although a more conservative approach would have them equal (since you don’t know how the consumer will load the trailer).

[Dan and Liz]

Just looked at tire reviews and found the Firestone Destination LE2 rated at or slightly above the Michelins. P235/75R15 XL load range 108T $107 per at tire rack. I'll keep looking and comparing though.

[Andrew T]

Hi Dan

In the early 90's all the large fifth wheels came with Goodyear Wrangler LT tires and the tread kept flying off of them. The tire would sometimes be sitting there still full of air but with the just the cords exposed and he tread completely gone. It turns out that they built the tire with the sidewall cords wraped around the steel belted tread. In a trailer application where the tires are fighting each other the tread plys sawed through the sidewall cords and the tires flew appart. Goodyear took great care of the affected customers and replaced thousands of tires as well as paying for a great deal of body damage.

Michelin assured me they would never build a tire that way and we have never had the problem with a Michelin. It is very hard to find he specifics of tire construction so that is why I am a little hesitant to use other brands. Most are likely just fine or maybe even better but you are experimenting.

Andrew T

[Dan and Liz]

Andrew -- thanks for the background--Interesting!

Dan

[Ridgerunner3]

Originally Posted by Andrew T

Hi Dan

In the early 90's all the large fifth wheels came with Goodyear Wrangler LT tires and the tread kept flying off of them. The tire would sometimes be sitting there still full of air but with the just the cords exposed and he tread completely gone. It turns out that they built the tire with the sidewall cords wraped around the steel belted tread. In a trailer application where the tires are fighting each other the tread plys sawed through the sidewall cords and the tires flew appart. Goodyear took great care of the affected customers and replaced thousands of tires as well as paying for a great deal of body damage.

Michelin assured me they would never build a tire that way and we have never had the problem with a Michelin. It is very hard to find he specifics of tire construction so that is why I am a little hesitant to use other brands. Most are likely just fine or maybe even better but you are experimenting.

Andrew T

Thank you Andrew. Your input has been very helpful to me in this discussion.

[switz]

I am pleased at how well my P235/75R15 XL Michelins tow and they do NOT build up heat, even at speeds at or above 65mph.

[CapriRacer]

I hate to burst everyone's bubble, but Andrew's story flies completely in the face of the way tires fail.

First, to my knowledge no one used sidewall plies over the belts. It's possible, but it makes no sense to do it that way. What Andrew MIGHT be saying is that the tire had a nylon cap ply over the belt - and that is a plus, not a negative.

Plus, I have absolutely never seen a belt saw though the cap plies. That's not the failure mechanism.

And lastly, it sounds like the tire was recalled - and if that is the case, then I know which recall (and tire) it is - and it didn't have a cap ply and it didn't saw through the ply cords. The failure mechanism was the usual - Belt leaving belt separation which starts under the top belt edge.

[Andrew T]

Hi Capri

That was the official explanation from Goodyear at the time, remember this was 18 years ago. The replacememt Wranglers had a special service designation on them that was not on the standard truck tire. It was long before digital cameras or I would likely have pictures. It was sure weird to see tires holding air with the tread completely gone.

The point I was trying to get accross was that all our work with 235 Passenger and LT tires has been with Michelins. The results with other tires could be every bit as good or better but I just don't know that for sure.

Andrew T

[CapriRacer]

Originally Posted by Andrew T

Hi Capri

That was the official explanation from Goodyear at the time, remember this was 18 years ago. The replacememt Wranglers had a special service designation on them that was not on the standard truck tire. It was long before digital cameras or I would likely have pictures. It was sure weird to see tires holding air with the tread completely gone.

The point I was trying to get accross was that all our work with 235 Passenger and LT tires has been with Michelins. The results with other tires could be every bit as good or better but I just don't know that for sure.

Andrew T

I appreciate the point you are trying to get across. The only issue I have is with the "official" explanation.

First, it would be extremely unusual for a tire manufacturer to offer an explanation through official sources. This is the sort of thing plaintiff's lawyers just love.

Second, is that the explanation offered doesn't make sense - so I suspect that was just some guy trying to make sense of what he was observing. He might have been a Goodyear employee, but I can assure you, he wasn't deep enough in the technical arena to offer an informed opinion - because the explanation doesn't make sense.

Photos? I don't need to see photos. I've seen literally thousands of failed tires. It's what I do. I've seen the progression of these types of failures from the start of the failure to the final result.

So I am suggesting that the "explanation" you have been given is incorrect.

[tkowalyk]

Originally Posted by switz

I am pleased at how well my P235/75R15 XL Michelins tow and they do NOT build up heat, even at speeds at or above 65mph.

We noticed a significant difference in the temperature of the AS tires, after switching to the 16" / Michelin LT combo (much lower).

When I just bought my new 27 Classic, I had the dealer swap the stock tires with the Michelins I put 4000+ miles on last season.

Enough said!

[Andrew T]

Hi Capri

So what do you think actually happened to those tires. I know it is hard to say without seeing them. They were recalled but only for RV applicaitons. There were thousands on trucks that never had a problem.

We pretty quickly realized the failures came depending on how much maneuvering the person did. For example a unit we had at 4 shows (where we do a lot of twisting to get them into position) separated on the way home from the 4th show. It had maybe 1500 miles on it. Others drove to California and back but used pull through sites etc. could go for quite a while without a problem. So it was definitely related to the tires opposing each other.

I did not hear the explanation directly from Goodyear but the fifth wheel manufacturer said that was the explanation they were given as an OEM.

I am asking because if there is another reason it would be good to know what it was to prevent it happening again.

Andrew T

[ROBERT CROSS]

Originally Posted by Andrew T

Hi Capri

So what do you think actually happened to those tires. I know it is hard to say without seeing them. They were recalled but only for RV applicaitons. There were thousands on trucks that never had a problem.

We pretty quickly realized the failures came depending on how much maneuvering the person did. For example a unit we had at 4 shows (where we do a lot of twisting to get them into position) separated on the way home from the 4th show. It had maybe 1500 miles on it. Others drove to California and back but used pull through sites etc. could go for quite a while without a problem. So it was definitely related to the tires opposing each other.

I did not hear the explanation directly from Goodyear but the fifth wheel manufacturer said that was the explanation they were given as an OEM.

I am asking because if there is another reason it would be good to know what it was to prevent it happening again.

Andrew T

Side strain while turning a dual axle?

I never realized just how much there is until trying to move/turn our very light dual axle boat trailer onto the pad.

Bob

[CapriRacer]

Originally Posted by Andrew T

Hi Capri

So what do you think actually happened to those tires. I know it is hard to say without seeing them. They were recalled but only for RV applicaitons. There were thousands on trucks that never had a problem.

We pretty quickly realized the failures came depending on how much maneuvering the person did. For example a unit we had at 4 shows (where we do a lot of twisting to get them into position) separated on the way home from the 4th show. It had maybe 1500 miles on it. Others drove to California and back but used pull through sites etc. could go for quite a while without a problem. So it was definitely related to the tires opposing each other.

I did not hear the explanation directly from Goodyear but the fifth wheel manufacturer said that was the explanation they were given as an OEM.

I am asking because if there is another reason it would be good to know what it was to prevent it happening again.

Andrew T

The typical failure for a steel belted radial tire is a “Belt Leaving Belt Separation” – commonly called (incorrectly) a “Tread Separation”. The failure starts as a small separation at the edge of the top belt. No, it is not an adhesion problem. It is a stress problem. The cause is a combination of the amount of distance between the belt edges and the properties of the rubber there.
After the separation starts, it grows between the belts until it is large enough for the centrifugal force to exceed the elastic strength of the rubber. At that point a flap is created. Sometimes the top belt (and the tread rubber above it) come off as a long continuous piece, but more often the flap encounters body work or folds over as the tire rolls and that piece is torn into smaller pieces.
The rest of the tire is usually intact. It holds air, although the casing in this condition is much more prone to punctures.
Can you tell what tires are more prone to this than others? Maybe.
Tires with cap plies are a plus: All tires have a construction listed on the sidewall, like this:
Sidewall: 2 polyester plies
Tread: 2 polyester plies, 2 steel plies, 1 nylon ply.
The nylon is the cap ply. It does 2 things: It reduces the stress by restricting the growth due to centrifugal forces, and it helps to hold the belt on even after the separation grows. This is not to say that you can not get a flap (and the rest of the failure mechanism), but it takes more stress for that to happen.
Speed ratings: Because centrifugal forces are a key component in the failure, a tire with a higher speed rating would be better. For passenger car tires, I recommend a minimum of an H speed rating – although this is just a shortcut to obtaining a tire with a cap ply.
I also recommend that tires have enough load carrying capacity to only be loaded to 85% of their rated capacity (as determined by the size and inflation pressure). This is across the board (passenger car, truck, etc.).
Put another way: I do NOT recommend using the load tables as is. Those are minimums, not a recommendation.
Age: Rubber deteriorates over time, but heat is a major factor in how fast this takes place. The states with the highest reports of these types of failures are (more or less in order) AZ, CA, TX, NV, and FL. Obviously the first 4 are in the hot Southwest, but if you take a look at the temperature in FL, you’ll find that it stays warm all year, and in winter is much warmer than AZ. This is all about heat history. For those of a technical bent, it’s called the Arrhenious Rule: Chemical reactions double in rate for every 10°C rise in temperature.
The above applies to any type of tire, but the following is specific to trailers:
Trailer manufacturers haven’t always be scrupulous about sizing tires. All too often, trailers are loaded beyond the GVW’s and GAWR’s – and the trailer manufacturer ought to be sizing everything to (and beyond) those conditions. For this reason, I recommend that everyone weigh their trailer – tire by tire. The load on the tires is not the same front to rear, nor side to side. Tires should be sized for the worst case.

[Action]

Originally Posted by CapriRacer

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Trailer manufacturers haven’t always be scrupulous about sizing tires. All too often, trailers are loaded beyond the GVW’s and GAWR’s – and the trailer manufacturer ought to be sizing everything to (and beyond) those conditions. For this reason, I recommend that everyone weigh their trailer – tire by tire. The load on the tires is not the same front to rear, nor side to side. Tires should be sized for the worst case.

I have first hand experience with this scenario. (Not a travel trailer) The max capacity of the trailer tires was only 200 pounds greater than the dry static unhitched weight of the trailer. True when the trailer is hitched to the TV some transfer of trailer weight was carried by the TV. However the total load was about 3 1/2 tons. Like mansy trailers it would sit for long periods of time.

Neglect max tire inflation, clip a curb, leave the tires uncovered in the AZ sun or any other type of issue and I had tire failures that in my opinon were too soon. It wasn't until I understood the razor thin capacity margin my tires had versus actual load is when I became very dilligent in tire maintence. And it started with a trip to the scales.

The trailer builder was more interested in building and selling trailers. Tires are a detail that is needed to get the package on the street. And while the tires had enough capacity for the load it was just barely a winner.

I can not endorse this action enough. (weighing the load) Until it is checked on a scale the data you have is just a suggestion.

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