Good Sam Club Open Roads Forum: Travel Trailers: Multiple Tire Blowouts
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Grit dog

Black Diamond, WA

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Posted: 09/02/19 11:27am Link  |  Quote  |  Print  |  Notify Moderator

Great thread boys!!
Don't let it die now....I wanna see 10 pages of bickering!


"Yes Sir, Oct 10 1888, Those poor school children froze to death in their tracks. They did not even find them until Spring. Especially hard hit were the ones who had to trek uphill to school both ways, with no shoes." -Bert A.

kedanie

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Posted: 09/03/19 08:54am Link  |  Quote  |  Print  |  Notify Moderator

Grit dog wrote:

Great thread boys!!
Don't let it die now....I wanna see 10 pages of bickering!

Yep, typical tire thread. The OP is long gone, lots of arguing about ST vs LT tires, plenary of meaningless documents and ultimately the so called self anointed tire experts arguing with each other!

Geeze guys, give it a break!

Keith


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CALandLIN

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Posted: 09/03/19 01:38pm Link  |  Quote  |  Print  |  Notify Moderator

gmw photos wrote:

CALandLIN wrote:

....snip

Any highway tire can be chosen by the RV trailer manufacturer as long as it falls within the FMVSS (standards).
....snip


Cal,
My point is that LT tires are "approved" by the trailer manufacturers.

You point out that any tire within the safety standards can be chosen as OE. Which is true. They mostly choose ST, because very possibly, they are simply the least expensive to fit, and may in fact meet the needs of many consumers.

However on this board and others, forum members will state that "LT tires should not be fit to trailers. They are made for trucks. ST tires should be fit, because they are made for trailers."

This statement is contrary to what the trailer companies state. In fact a growing number of trailer companies are fitting LT tires as OE, either as standard or extra cost option.

Major point is, LT tires "CAN" be an option on a trailer, in spite of what well meaning forum posters may state.

And yes this is a much repeated forum topic, but new folks are constantly coming into the fold, looking for solid information. It makes sense to me that we repeat the dialog as often as needed.

best regards to all, gmw


I try real hard not to obfuscate.

The way you phrased “approved”, appears as an open blanket approval. It’s not. Tire selection and approval is the vehicle manufacturer’s prerogative for each application. With their selection comes the task of certification. No matter how consumers react to the validity of the federal certification label affixed to their vehicles does not lesson its binding effect on vehicle manufacturers. The tire designated size listed on that certification label sets the minimum standard for that vehicle. It trickles all the way down to replacements and the tire industry standard that says replacements must be the same size as the OE tires and able to provide a load capacity equal to or greater than what the OE tires provided. It has a caveat; deviations must be approved by the vehicle manufacturer or offered as options (SAFECAR or in the individual owner’s manual refers).

The vehicle manufacturer is directed by FMVSS (standards) to select tires appropriate for the vehicle they are fitted to and then set the recommended cold inflation pressures. Thus that inflation pressure becomes the minimum standard for the OE tires unless there are deviations in the individual vehicle owner’s manual or on a secondary tire load and inflation placard. (FMVSS 571.120 refers).
Things to put in the memory bank: Designated size has always been the official correct size nomenclature for tires. It’s becoming more important as tire manufacturers and their retailers become better trained. P225/75R15, ST225/75R15 and LT235/75R15 are all designated sizes and none of them are interchangeable.

The LT tires normally used in the current RV trailer market are actually what I call hybrid. That’s because they are marketed as Regional Service Trailer (RST) tires and have the same restriction on their sidewalls as ST tires. Up in the heavier applications, truck tires designed for service on low platform trailers are used and are normally 17.5” in diameter. However, Airstream fits some of their high end trailers with standard LT tires and offers them as options on other models. About 35-40% of all dual axle bass fishing boat trailers I observed at a recent show had OEM Passenger tires. The last RV trailer I observed with OEM passenger tires was a Dutchman Denali. It had 20” wheel/tire assemblies.

It’s very easy to be out of context when writing about tires. The reason is no single reference totally explains things from start to finish or, how they fit together. Government regulations/standards/rules are precise and there is nothing between the lines. All of us have a tendency to read-in things that are just not there. When the document says to do something, it’s directed at the responsible party – the vehicle manufacturer – and no others. In one section of the standard it says the tire must provide a load capacity not less than the load capacity of the axle system it’s fitted to. If you stop there you stopped too soon. In another standard the vehicle manufacturer is directed to fit tires that are appropriate for the vehicle they are fitted to. If they are not comfortable with the previous written minimum standard they can set it higher with their selection, which than becomes the minimum standard for the vehicle. Why? You might ask. Because they must certify their selection which came from a document of minimums.

RV trailer brochures do not provide a true reference for many things including tires. Your trailer’s brochure may list the trailer’s axles as 5200#. A true statement but inaccurate because the trailer manufacturer has the authority to recertify them to a lower capacity and certify them to 5080# which will be on the vehicle certification label.

kedanie

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Posted: 09/03/19 08:43pm Link  |  Quote  |  Print  |  Notify Moderator

OK Calvin, nobody cares any more. Nobody’s going to read your long stories about tires that only you believe!

Time to give it a rest.

Keith

Huntindog

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Posted: 09/04/19 12:21am Link  |  Quote  |  Print  |  Notify Moderator

All of this sounds to me like a way for the manufacturer to legally put a certain tire (Cheap) on a unit. Actual performance becomes secondary to the "paper trail" which is just a CYA to absolve them of responsibility for failures.

Caland Lin wrote:

In another standard the vehicle manufacturer is directed to fit tires that are appropriate for the vehicle they are fitted to. If they are not comfortable with the previous written minimum standard they can set it higher with their selection, which than becomes the minimum standard for the vehicle. Why? You might ask. Because they must certify their selection which came from a document of minimums.


In my case, I am uncomfortable with the low minimum standards set by the manufacturers.. So I choose to fit tires with standards that exceed the minimums.

Of course since the manufacturer did not "certify" my choice, this act absolves the manufacturers of any responsibility for my choice.
But the afore mentioned "paper trail" also absolves them of responsibility for failures... A very good deal for the TT manufacturers.

BUT, and it is a BIG BUT. I have NEVER had a TT manufacturer step up and pay for ANY tire caused damage to any of my TTs. They have not been the one on the side of the road changing my tires, or paying for them.... And I have never read of this occuring to anyone else either... Why? They have this legal documentation that protects them.

You seem to be saying that we as consumers have no choice, but to replace our tires with the same junk that has repeatadly failed some of us.

I have very little use for lawyers, Manufacturers and govt. whose primary function seems to be to CYA each other, while some make big profits off of the unaware, and according to you helpless consumer.
I also have little use for those that parrot their talk in an attempt to justify it. As they will not be on the side of the road changing my tires or paying for them either.

And since that is what I believe, and it is my TT, and my life, I will use tires that have proven to perform much better than what is "required" and be more reliable to boot. As always. MY money, My choice


* This post was last edited 09/04/19 08:25am by Huntindog *   View edit history


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midwest

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Posted: 09/04/19 07:25am Link  |  Quote  |  Print  |  Notify Moderator

Cal,
Thanks for taking the time to write out something that seems like a rather complex way of looking at the subj.

I'm not sure what to think of all the details.

What I do know is that I have two trailer manuals, from two different companies here, that say when selecting replacement tires, I can use LT if I so choose.

That's good enough for me. I'm not equipped to argue the semantics of of "approval" vs "a long list of federal certifications".

I like LT tires on my trailers. I have used them with much luck. I've used ST tires also. Not so much good luck with them.

warm regards, gw

ps, I do make sure I am choosing replacement tires that have load rating that is in excess of the actual load being carried, and also is in excess of the axle rating. I never run with overloaded tires or axles. My travel trailer has 7600 pounds of LT tire capacity, with 3600 actual pounds on the axles.
My small horse trailer has 8400 pounds of LT tire capacity under an actual load of no more than 5500 axle pounds. Etc., on my other trailers. This has worked well for me with LT tires.

It did not work well for me with ST. For the first year of my two newest trailers ( 2016 ) I tried getting by with running the factory OE ST tires. One failed on the horse trailer ( Provider brand ) and one failed on the equipment trailer ( BCT brand ). I don't know why they failed. They were inflated correctly on the morning of failure in both cases. I didn't agonize over either. Both trailers now have LT, and have run without failure since then.

CALandLIN

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Posted: 09/04/19 08:28am Link  |  Quote  |  Print  |  Notify Moderator

gmw photos wrote:

Cal,
Thanks for taking the time to write out something that seems like a rather complex way of looking at the subj.

I'm not sure what to think of all the details.

What I do know is that I have two trailer manuals, from two different companies here, that say when selecting replacement tires, I can use LT if I so choose.

That's a vehicle manufacturer option and their choice to do so. However, do they tell you how to go about insuring the switch to the LT tires can be accomplished and stay within the acceptable tire industry safety parameters?

That's good enough for me. I'm not equipped to argue the semantics of of "approval" vs "a long list of federal certifications".

I like LT tires on my trailers. I have used them with much luck. I've used ST tires also. Not so much good luck with them.

warm regards, gw

ps, I do make sure I am choosing replacement tires that have load rating that is in excess of the actual load being carried, and also is in excess of the axle rating. I never run with overloaded tires or axles. My travel trailer has 7600 pounds of LT tire capacity, with 3600 actual pounds on the axles.
My small horse trailer has 8400 pounds of LT tire capacity under an actual load of no more than 5500 axle pounds. Etc., on my other trailers. This has worked well for me with LT tires.

It did not work well for me with ST. For the first year of my two newest trailers ( 2016 ) I tried getting by with running the factory OE ST tires. One failed on the horse trailer ( Provider brand ) and one failed on the equipment trailer ( BCT brand ). I don't know why they failed. They were inflated correctly on the morning of failure in both cases. I didn't agonize over either. Both trailers now have LT, and have run without failure since then.


The reason ST tires are so hard to replace with LT tires is load capacity. Here are a couple of examples. The ST225/75R15 LRE has a maximum load capacity of 2830# to match that load capacity with a LT tire will almost always require new 16" wheels and tires. A lot of RV trailers do not have the axle spacing for the taller tires. The ST235/85R16 LRE has a maximum load capacity of 3640#, the LT235/85R16 LRG has a maximum load capacity of 3750# and is one of the few fitments that will work by going up with the available two load range increases and using wheels that will support the 110 PSI necessary to gain equal load capacity from the LRG tires.

p.s. providing tires for the actual load carried is not from the FMVSS standards and is not applicable for RV trailer tire fitments.

JIMNLIN

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Posted: 09/04/19 09:06am Link  |  Quote  |  Print  |  Notify Moderator

Quote:

In my case, I am uncomfortable with the low minimum standards set by the manufacturers.. So I choose to fit tires with standards that exceed the minimums.

Of course since the manufacturer did not "certify" my choice, this act absolves the manufacturers of any responsibility for my choice.
But the afore mentioned "paper trail" also absolves them of responsibility for failures... A very good deal for the TT manufacturers.

Good point.
the only requirements from the FMVSS is for the trailer mfg to show his tire choice on a tire placard which does nor place any legal obligations for a down stream owner(s) to replace with the same.


"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers

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midwest

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Posted: 09/04/19 09:21am Link  |  Quote  |  Print  |  Notify Moderator

Well, okay Cal, but let's just say that honest men shall disagree here. I see this whole load capacity thing in simpler terms. On the four trailers I currently run, one has 14", one has 15", the other two have 16". I have not had any problem choosing LT tires with adequate capacity, plus a safe reserve.

Let's use my most recent trailer as an example. 7500 GVWR. 3500 axles.
I use good year wrangler ht, 15" LT tires that are 2096 ( let's call it 2100 ) at 65psi.

For simplicity sake, let's assume it's balanced across all four tires, although it may not/probably not.

So I have 7000 pounds of axle capacity. I have 8400 pounds of tire capacity. 7K divided by 8.4K is 83%. I am happy with a worst case scenario of 17% reserve load capacity of my replacement LT tires. I know for fact, CAT scale verified, loaded for a show, with my quarter horse in the trailer, I do not have that much weight. More like approx 6K pounds or less, total including the tongue weight, which is of course carried by the truck, not the trailer axles. So the bottom line in this case is I have about 5300 pounds on the axles. I feel I am safely under all the stated limits.

As I have said before, numerous times on this forum, I would encourage each viewer here to take their rig to the scale so they know what they are really dealing with.

I have not seen any part of any of this, over the years, that goes beyond basic junior high school math.

As always, I really do consider these to be good discussions, because it often results in new trailer owners heading down the path of thinking, and research.

CALandLIN

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Posted: 09/04/19 11:54am Link  |  Quote  |  Print  |  Notify Moderator

I’m not writing tire posts to be argumentative. I research what I say and have references to support the information in my posts. How a person perceives my messages can be clouded by the way regulations, rules and standards are written or disseminated.

A big confusion factor about replacing RV trailer tires is the lack of standardized recommendations from the trailer manufacturers. You drive your car, truck or other motorized vehicle into a tire retailer’s location to inquire about replacements. They will search their data base for acceptable replacements for your vehicle. They already have all the vehicle manufacturer’s recommendations and can immediately give you a list of tires by size and brand to choose from. That procedure is nonexistent for RV trailer tires. The best you can hope for is a list of the same designated size shown on your trailer’s certification label with a variation in load ranges when available. A call to the RV dealer/manufacturer will in all probability result in the same selections.

Here’s some official stuff.

Vehicle owner’s manual wording:

To maintain tire safety, purchase new tires that are the same designated size as the vehicle's original tires or another size recommended by the manufacturer. Look at the tire information placard, the owner's manual, or the sidewall of the tire you are replacing to find this information.

Tire industry wording:

Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.
Tires should always be replaced with the same size designation — or approved options — as recommended by the vehicle manufacturer.
The correct tire size designated for your vehicle should always be verified with the information in your vehicle owner’s manual and/or the vehicle certification label.

In the USTMA industry standards from the RV chapter page # 43 has this caveat; “However, never use inflation pressure lower than specified by the vehicle tire placard, certification label or owner’s manual. Nor should inflation pressure exceed the maximum pressure molded on the tire sidewall.”

There is an industry standard used to set recommended cold tire inflation pressures for replacement tires having a different size designation than the OE tires. It stipulates that they must provide a load capacity equal to the OE tires by inflation pressures.

Like Jim pointed out above, these are none binding standards for the consumer unless there is a state regulation that enforces them. However, they are minimal standards and when you are operating outside those standards you can be held accountable for your actions.

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