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Old 11-03-2020, 11:47 AM   #21
gearhead
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Originally Posted by CWtheMan View Post
They are low platform commercial trailer tires. Except Sailun, those are manufactured as ST tires.

Most of the RV trailers with 8000# axles come from the factory with 17.5" tires. The GY G114 seems to be the most popular.
Attachment 30624
Yes, 17.5 is what I have.
The Goodyears may be popular but mine came from the factory with Sailun. Goodyears are probably standard equipment on Mobile Suites. I'm thinkin a fair percentage of OEM Goodyears are replaced with something else when the price tag is discovered.
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Old 11-03-2020, 03:33 PM   #22
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Same here Danny. I know a boy that hot shotted until a couple years ago. Typical rig...deleted Ram Cummins and a 40ft gooseneck. Hauling oilfield junk all over. He ran Hercules and was happy enough with them to recommend them to my son for his heavy duty low boy tongue pull. My son isn't very careful about checking air pressure or covering the tires from UV. I know those tires hauled a heavy construction tractor to Dallas and I pulled a Jeep Grand Cherokee across Houston on them.
There was, or is, a relationship between Cooper and Hercules. My small town tire shop owner said Cooper had input on the rubber formula. Who knows. I believe Hercules is owned by someone like American Tire Distributors, or similar.
Hercules may be easier to find, not sure. After our blowout I called several tire shops around Bernalillo NM. No one had a Sailun. I called Discount Tire and they recommended the Hercules or Provider. They had them in their local warehouse. I picked Hercules and had it installed the next morning. I have the Hercules dealer here in Liberty maybe 1/2 mile from me. I'm leaning in his direction. I'll pull the trigger after New Years.
Our 5th went to the shop September 21 for the blow out damage and they are just getting their estimate to State Farm. They did work a couple other small issues though. I've done business with this shop for 30+ years. May not be much longer. You know the saying: "shirtsleeves to shirtsleeves in 3 generations". Grandpa starts a business and works it hard to be a success, son inherits it and does well too, grandkids inherit it and put it on auto pilot and run it into the ditch.


^^That is exactly my situation in my little town. Great responsive store under dad (the guy that worked non stop and built it up) and now under grandson....I don't go there anymore. Prices are sky high, can't/won't do thing right and have to take stuff back - I quit going and started going to Discount tire 60 miles away.
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Old 11-03-2020, 03:49 PM   #23
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Yeah Discount is my default go to tire shop.
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Old 11-07-2020, 08:02 AM   #24
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ST tire failures

You know, I’ve been writing about RV trailer tires for more than 17 years. I’ve explored, reviewed, researched and written about thousands of tire failures that occurred while in use as RV trailer tires. Many of my conclusions are drawn from multiple failures from single causes although unknown by the consumer.

When reading this please take into account that I’m a serious study of the rules, regulations and standards used by the industries that have approved the tires for use as high speed trailer tires. I’ve read ever DOT/NHTSA tire rules committee report, approval/disapproval since 2003. I’ve read some of them so often I can reference them without rereading them (again).

The evolution of ST tires used on our RV trailers is directly linked to the needs of the trailer industries. As more and heavier trailers were built, the ST tire manufacturers were being driven to provide more designated sizes and load ranged tires to support the demands of the trailer industries. Because of import/export rules, almost all of the off shore ST tire manufacturers have always had a huge advantage in pricing, which (IMO) caused almost all of the USA manufacturers to not waste their time building tires that were going to be very difficult to sell to a market that had numerous tires on their USA shelves at much lower prices.

The Tire and Rim Association (TRA), an organization with approval authority for the construction and standardization of the ST tire design, set a 65 MPH maximum operational speed restriction for all ST tires. Because there is no official speed letter for 65 MPH, there was no authority to force those manufacturers to provide that information on the tire sidewalls.

Enough lead-in info, let’s get to the meat of the posting. I’ll add references as I go from here.

So, where do RV trailer manufacturers get the tire/wheel assemblies, suitable for fitment to specific RV trailer axle loads? They get them from suppliers of OEM equipment. The tire is from a tire manufacturer and the wheel from a wheel manufacturer. The tire manufacturer provides the installers with approved rim sizes for the tires. Load and PSI needs will be provided by the needs of the axles they are earmarked for. Yup, were getting to some of the meat. The OEM provider will almost always assemble the wheel/tire assembly to a request made by the vehicle manufacturer. If the vehicle manufacturer’s request has not provided a PSI setting for the assembly, the tires will normally have the PSI value used to set the bead. If the factory installer fit's that assembly to an axle without a PSI request from where it’s going to be fitted to a vehicle, it will still have that bead setting PSI in it. Eventually, as the trailer progresses along the production line the tires will become overloaded. If at final vehicle certification the pressures are not increased to recommended cold inflations for the fitment, the trailer will be turned-over to a delivery agent. Will the agent inflate to recommended cold? The tire damage started just as soon as it became overloaded. It could then be more severely damaged by being severely under inflated for transport and having its delivery speed increased beyond 65 MPH. Once at the dealer location it will continue to degrade from overloading until someone discovers the under inflated tires. The damages have been done. Tire damages are cumulative. Those tires are going to fail long before their predicted life span. Maybe that will happen on the way to their new home.

If you want an installment 2,3,4 etc.. Let me know. I’ve just barely got in the door
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Old 11-07-2020, 10:50 AM   #25
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^Go for it..
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Old 11-07-2020, 03:24 PM   #26
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Part #2

When a consumer has the luck to get a new trailer without some sort of tire damage, the ST game begins.

Consumers new to ST tires will make a lot of mistakes trying to properly maintain them. It’s much more complicated than maintaining tires on an automotive product. Although RV trailer tires and automotive tires conform to the same standards, there are major differences. Those differences are argued constantly in RV trailer forums. The first difference causes the most problems resulting in early ST tire failures, some catastrophic. RV trailer tires are not required to have load capacity reserves. All automotive tires must provide a percentage of load capacity reserves. Throughout the RV trailer industry its common knowledge that RV trailer axles are notoriously unbalanced. It can be an entire axle load imbalance or a single tire position imbalance. With tires providing zero load capacity reserves those imbalanced tires have a very high probability of failing and failing very early. I’m going to add a picture of a Keystone trailer’s certification label that depicts its GAWRs being set (by Keystone) at 5080# so the tires shown on that certification label can be used. Those tires provide – do the math - 2540# of load capacity at the PSI value, also shown on the certification label. The probability of having at least one tire severely overloaded on that trailer is very high.

Basically, the speed rating is telling us the tire can carry its maximum load capacity depicted on its sidewall. As the speed is increased beyond the speed rating the tire will overheat and start to degrade. Each time it degrades it’s added to the previous degrade. We had zero load capacity reserves and the degrading is eating away at the tires maximum load capacity. Something has to give.

A few years ago our government (USA) threatened most of the off shore manufacturers with increased tariffs if they did not mold a speed rating or speed letter to the tire sidewall. Although the load index system is not the official load indicator for LT & ST tires the load index system is used to display tire speed letters. (There is no letter for 65 MPH). The agency tasked with the responsibility of insuring that speed rating/letter is on the tire is US Customs. The only ST tire I know of that does not have a speed rating is Maxxis. According to TRA, an unmarked tire defaults to 65 MPH, no excuses allowed.

The regulation/standard allowing minimum tire load capacity equal to the GAWR has not changed. However, a few years ago (2017) RVIA, a large private membership organization mandated that all participating members (about 98% of all RV trailer builders) provide Original Equipment tires with the ability to provide at least 10% in load capacity reserves above the vehicle certified GAWRs. That RVIA recommendation will de facto effect all replacement tires recommended load capacities. That’s because of the industry wide standards that require all replacement tires to have a load capacity equal to or greater than what the OE tires provided.

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Old 11-07-2020, 03:46 PM   #27
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So mechanically speaking, are the increased failures when going over the rated speed due to increased frequency of sidewall flex, belt separation, or ?
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Old 11-08-2020, 12:16 AM   #28
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So mechanically speaking, are the increased failures when going over the rated speed due to increased frequency of sidewall flex, belt separation, or ?
When it comes to tire mechanics I rely on the more experienced posters like Tireman9 for answers. From my point of view, tires are going to start degrading when subjected to speeds greater then what they were designed to resist.

Speed ratings for ST tires have become very controversial since they started using ratings higher than 65 MPH on their sidewalls. Because I don’t have access to confidential TRA manuals I cannot argue with those that do. However, from knowledge of how the systems work, I find it very improbable that the largest tire manufacturer in the world (GY) would introduce a completely new line-up of ST tires and give them a speed rating of 87 MPH without NHTSA approval. Somewhere in that process NHTSA was assured by GY that their new line-up was tested for the 87 MPH limit.

As for a tread separations, who knows, they are normally caused by numerous misuse factors. Sidewall flex is another engineering subject. Each tire design (ST - LT – P) is different and tested for different factors to correspond with their expected usage. However, they can all be used on RV trailer axles. That’s a decision only the trailer manufacturer can make for OE tires.
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Old 11-08-2020, 12:35 PM   #29
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Part #3

Tire selections: Is it done by monopoly, supply and demand, design characteristics, popularity, low bidder or just plain old money. Probably some of those are in combinations.

Whatever the madness is, it all boils down to the individual manufacturer. They have the sole responsibility for Original Equipment tire selections and fitments on their vehicles and in the end they MUST certify those selections. The vehicle manufacturer has the option to use any of the DOT approved highway tires. They can also offer a limited number of options. Once they make the final decisions don’t try to get them change designations or designation sizes. It’s not going to happen. It would mean they made an error and such an error could cause them initiate a recall. Recalls are expensive and are, at all costs, avoided by vehicle manufacturers. However, brands with the same designated size as the OE tires can be requested from dealers because there are no certifications required to do so.

That sort of leads me into designated sizes. In the NHTSA 2010 rules committee meeting, they approved that all tires are to be referred to by designated size. ST235/85R16 is a designated size. LT235/85R16 is a different designated size. In the eyes of tire regulations and standards they are not interchangeable, even when used as a plus size.

To understand the why, requires an understanding of precedents. Senior government regulations provide the information their underlings MUST follow. 49 CFR (a code of federal regulations) sets the stage for the use of designated tire sizes. So, when the vehicle manufacturer applies the standards in FMVSS – standards they must use to build trailers – they mention designated sizes in the fitment applications. FMVSS (standards) are minimum in nature, therefore, the tire designated sizes found on the vehicle certification label and their recommended cold inflation pressures are minimum standards. When one looks at the tire industry standards for replacement tires they clearly say that replacement tires MUST have a load capacity equal to or greater than what the OE tires provided.

NOTE: Within the 49 CFR tire document; using a designated size that differs from the certification label is cause for rejection. (No one can disregard that without violating a safety standard).

In the automotive industry, vehicle manufacturers provide listings of recommended designated tire sizes for replacement of the OE tires. In the RV trailer industry that procedure doesn’t exist. NHTSA, in its wisdom, has mandated that a statement about tire replacements MUST be in all RV trailer owners’ manuals. Here is a verbatim quote from the Keystone manual.

“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 and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire dealer.”
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Old 11-08-2020, 04:55 PM   #30
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You know, I've been on the road for 4 days and finally landed. My eyes usually glaze over when we go beyond tire common sense and facts and dive into the deep minutia. CW I just got here and started reading this and it is interesting to me - thanks.
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Old 11-10-2020, 07:48 AM   #31
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Part #4

Okay, I’m going to reiterate a little bit here. RV trailer manufacturers MUST abide and adhere to all standards in FMVSS when building your trailer. NHTSA directs FMVSS to develop standards that support minimum values. No vehicle manufacturer has the authority to lesson those minimums. Therefore, when certified by its vehicle manufacturer, an RV trailer has met all those minimum requirements.

Now, let’s get down to tires. Because of the wording in FMVSS, the designated size of the tires on the vehicle certification label is considered as minimum. Everything in our RV trailer industry revolves around minimums. It’s a safety violation to deliberately use anything less than the minimums.

NHTSA, in SAFECAR says the vehicle manufacturer’s recommended cold inflation pressures for OE tires are the correct inflation value for that vehicle. USTMA tire industry standards say that replacement tires MUST provide a load capacity equal to or greater than what the OE tires provided via recommended cold inflation for them.

To take a step backward I’m going to quote from a FMVSS standard. It’s just in part but it’s enough to get the drift. Actually this is from two standards. One says that OE tires for vehicle certified axles on RV trailers MUST provide a load capacity equal to or greater than the GAWRs. In the final fitment standard the vehicle manufacturer is directed to set a recommended cold inflation pressure that is appropriate for the axles on that vehicle.

Here’s a little raw meat to grind your teeth on. Before the RVIA 10% reserve recommendation a very large percentage of RV trailer tires could barely hold-up to a fully loaded RV trailer. Here’s a hypothetical. A couple of ST205/75R14 LRC tires are OE on 3500# axles. Those tires at their maximum load capacity of 1760# at 50 PSI are in real danger. With a loss of 5 PSI down to 45 the tires are only providing 1640# of load capacity. If this is a single axle trailer, the total load on the axle can be less than maximum - it can also happen on dual axels. However, the danger lies in an unbalanced axle with one tire position 200# above tire load capacity MAX.

Next up, the long winded replacement tire standards.
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Old 11-11-2020, 03:54 AM   #32
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Part #5

OKAY, here we go; RV trailer replacement tires. To the RV trailer owner, this is probably the most confusing topic. The factors leading into the replacement action are basically the same as automotive tires. However, RV trailer tire replacements are commonly done by trailer owners. They seek help from unprofessional sources that often provide inaccurate, unsafe recommendations. In this post I’m not going to delve into automotive tire replacements. They differ, and besides that, they are supported by vehicle manufacturers with lists of approved options the tire dealer can use to help them choose the right tires, even plus sized and “P” to “LT”.

First and foremost is the fact that all designated sizes are standardized to provide identical load capacity within that designated size. Speed letters and load capacity letters for load ranges are not part of a tire’s designated size. If present at the end of a tire designated size it’s for informational purposes only.

My definition of tire strength for this post is a tire’s ability to carry a maximum load. A tire’s durability factors have nothing to do with a tire’s strength.

Some brands provide more durability than others. ST tires now have at least two brand names building 15” & 16” rugged off road tires with more durable treads and sidewalls. Those features do not add strength. Some brands now have scuff guard inserts built into the tire’s sidewalls, they do not add strength. Nylon belt overlays are not required for ST tires. Almost all of the major brands now have nylon overlays on 15” & 16” ST tires to help prevent tread separations. Again, that addition does not add tire strength. I mention those few items to encourage the consumer to look for them when considering replacements for the OE tires. All steel constructed tires may be more durable than the standard polyester tires. Currently they are only provided in LRG for 16” tires and LRF &LRG for 15” tires. Their load capacities are identical to polyester tires of the same size designation and load range.

So, now I’m going to get to replacement tire standards for RV trailer tires. The following information is supported by excerpt information found in the FMVSS, 49 CFR part 567 - vehicle certification, USTMA manual for RV tires and a little help from some of the automotive SOP manuals.

First I’m going to establish that when I write a tire size for the first time I’ll refer to it by its official designator, – designated size- after that I may just say tire size.

NHTSA says a tire’s official size is defined as designated size or size designation. It’s important to recognize that when selecting your replacement tires. A designated size for special trailer tires is ST235/85R16. If you see them advertised as 235/85R16 someone didn’t know the proper nomenclature. Vehicle certification labels can be recalled for providing incorrect tire size designations.


The only official deviations from those OE tires will have to be approved by the vehicle manufacturer via an options list, if there is one for that particular trailer. I’m going to do this from a consumer/installer point of view. When the search begins, go and take a look at your vehicle certification label (On RV trailers the certification label is on the left external section of the frailer forward of the axles). The size designation of the official OE tires is displayed on that label. All replacement tires must have the ability to carry the load capacity those certified tires can carry at their recommended cold inflation pressures. Upgrades within a designated size may be available with a higher load range for that size (OE LRC to replacement LRD). Size changes such as OE ST205/75R14 to ST215/75R 14 is known as “Plus Sizing” and would have to be the trailer manufacturer’s option.

When replacing an OE tire with one of the same size having a higher load range, say LRC to LRD, there is nothing special to do. Both tires conform to the same load inflation chart for that size. What has happened is the owner now has the option to increase inflation pressures from LRC 50 PSI to LRD max 65 PSI giving the trailer owner much more load capacity reserves for his axles. I’m just going to mention this here, always change valve stems and use metal caps. Always insure the OE wheels can support the maximum PSI – they can already support the axle loads or they wouldn’t’ be official OE wheels - for the replacement tires. If/when plus sizing always insure the new tire/wheel assemblies have sufficient wheelwell clearances. (Remember, Wheel manufacturers MUST provide specifications on request).

When replacing OE tires with others in the Plus Size category there are some rules that must be followed. First and most important is the industry wide standard that replacement tires MUST have a load capacity that will be equal to OE tires load capacity at the vehicle manufacturer’s recommended cold inflation pressures. With the exception of vehicle manufacturer options, the designated size must be the same design as the OE tires. The most common option with a different designation is the LT235/85R16 LRG. It was offered quite often as a replacement for ST235/85R16 LRE because it has more load capacity and was desirable on vehicle certified GAWR 7000# axles. However, you won’t see that anymore because the RVIA minimum recommendation for 7000# axles is 3850#. GY and Sailun both built that LT tire as a regional service (RST) trailer tire for RV axles only. Sailun quit building it when they introduced the ST235/80R16 all steel LRG tires. Because the GY G614 was also used as OEM they still build it but I suspect that will quit when those OEM tires age out. Anyhow, it’s a misapplication to use a tire size designation other than the one on the certification label without recommendations from the vehicle manufacturer. There are 3 regulations plus the industry standards that support that statement.

Once the plus sized tires have been selected and all other fitment standards have been met, it’s important to register the new tires. There are a couple of technical actions that should be followed to protect all other owners of the vehicle. First is load capacity. A new recommended cold inflation pressure is needed for the replacements. Individual load inflation charts for the old and new tires will be needed. Look at vehicle certification label and determine what the load capacity of the OE tires is at the recommended cold inflation pressures. Use the load inflation chart for the new tires to set a new recommended cold inflation that will equal or exceed what the OE tires provided. Most will go up at least 5 – 10 PSI above minimum. Write that new number down and find the vehicle owner’s manual and pencil it in near the old number. Find some all weather material and build a supplemental tire load and inflation label and place it adjacent to the vehicle certification label. I’m going to insert a picture of an auxiliary label. It’s for automotive tires and you can just modify it to display your new tire size and inflation pressures.

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Old 11-11-2020, 05:32 AM   #33
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So is the Supplemental Tire Cold Inflation label any more than a reminder to us senile RV owners? I can't imagine it being legally required. Just sounds like superfluous verbage to me.
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Old 11-11-2020, 07:45 AM   #34
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So is the Supplemental Tire Cold Inflation label any more than a reminder to us senile RV owners? I can't imagine it being legally required. Just sounds like superfluous verbage to me.
It's use is approved by NHTSA.

That particular one came from a Bridgestone SOP pdf.

Without a recommended cold inflation pressure, how does one calculate over/under inflations?

The USTMA says a tire found to be 20% below it's recommended cold inflation pressure is in a run flat condition. Where would that 20% be without a starting point?

Bottom line, Knowing the designated size of the tires on the vehicle and their recommended cold inflation pressures is a need to know, especially for someone servicing the tires in the absents of the owner.
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Old 11-11-2020, 01:13 PM   #35
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If it's a trailer tire I air it to max pressure on the sidewall. I believe that is what Carlisle recommends. Really doesn't matter to me what the load is as long as I'm not overloading the the trailer. I have a tandem axle boat trailer that's rated for 4,000#, mostly I think to avoid brake requirements. I have owned that boat & trailer since bought new in 2014. I have never weighed it and probably never will. I did step up a load range to LR "D", I think, 65psi. I air them to max and get on down the road. The 5th wheel has H rated and calls for 123psi which is what I run them. My Ram dually I run at what my yellow sticker says when loaded. When unloaded I drop the rears down to 45, maybe 40, maybe 42.
Nobody but me ever airs up my tires.
I know common sense isn't very common, but..
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Old 11-14-2020, 06:09 AM   #36
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Valve Stems

They come in numerous designs, sizes and pressure ratings. Most RV trailer wheel assemblies having recommended cold inflation pressures of 80 PSI or less are going to have some sort of rubber or rubber metal snap-in valve stems with some sort of plastic/vinyl caps.

Because the internal structure of the valve stem have rubber seals it’s always recommended to replace valve stems with every tire replacement. The USTMA recommends the use of all metal valve stems and caps. For emergency sealing of a leaking valve stem, I recommended adding a package of replacement cores for your particular valve stems and a core replacement device to your maintenance supplies.

Personally, I recommend the shorter valve stems. They are less susceptible to debris damages and more receptive to add-on TPMS equipment.

Very good metal caps with their own rubber seals are highly recommended. They reinforce the valve stems sealing devices and protect against water intrusion or other damaging materials.

Poorly maintained valve stems and those not having the required PSI values for your tire pressures are high on the list for causing tire failures/catastrophic tire failures.

There are numerous types and sizes to choose from as shown in the link below. Choose the ones that best fits the needs of your wheel/tire assemblies.

https://www.bing.com/images/search?q...mageBasicHover
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Old 11-30-2020, 10:36 AM   #37
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TV Tires

I don’t often comment on tow vehicle tires (pick-up trucks). However, that doesn’t mean I haven’t researched them.

We see a lot of comments about TV tires and especially their inflation pressures. Some will misunderstand the recommended inflation pressures for them. Although the directions for selection, instillation and inflation come from the same set of standards (FMVSS), the procedures differ between ST and P/LT tires.

P/U truck manufacturers provide load capacity reserves with the installed axles. According to standards, the tires must have a load capacity equal to the installed axles GAWRs. OE tires recommended inflation pressures MUST be set with a recommended cold inflation pressure that is 94% of the maximum load of the OE tires. It’s called “normal load”.

According to standards, RV trailers are fitted with axles that will carry the fully loaded trailer (GVWR). Again, according to standards, the tires fitted to those axles must provide a load capacity equal to or greater than the GAWRs.

The RVIA recommendation: Remember it’s just a recommendation and not binding on the vehicle manufacturer. However, about 98% of the RV trailer manufacturers are members of RVIA and must follow the recommendation or forfeit the use of the RVIA certification label.

There is a catch 22; it’s within the established tire industry standards that all replacement tires MUST provide a load capacity equal to or greater than what the OE tires provided. About 3-5 years from the RVIA recommended action, at least 98% of all trailers will have OE tires providing at least 10% in load capacity reserves, certified on the vehicle certification label as OE.

I’m not going to dig deep into the TV tires. I will say this; in the document provided below starting on page 396 you will find a statement that I’m often quoting; NEVER use inflation pressures less than vehicle manufacturer recommendations.

http://www.fordservicecontent.com/Fo...EN_10_2019.pdf
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Old 11-30-2020, 11:17 AM   #38
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Well yeah Ford is going to say that. About 50% of our population is composed of complete idiots. (None of us on the forum of course) Ford is going to CYA on that. I air down my dually tires as soon as I store the 5th at home. All the tires are supporting is the axle and a percentage of the truck frame and body. But contrary to Fords assumption, I do air them back up before I hitch up.
A question...my Ram came with short little valve extensions. I decided I wanted longer extensions made of something besides plastic. Also the extensions are air loaded...they always have air pressure in them because they have a spring loaded button that is pressed to add/subtract air rather than a traditional cap. That worried me. That button is exposed to the world. So I tried some cheap Chinese extensions that didn't work. I never could get them in the sweet spot where they weren't leaking, to the spot where they would accept air. Then tried Milton brand, same thing. So I went back to the plastic. Still don't like it. You know any solution?
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Old 11-30-2020, 12:18 PM   #39
CWtheMan
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Originally Posted by gearhead View Post
Well yeah Ford is going to say that. About 50% of our population is composed of complete idiots. (None of us on the forum of course) Ford is going to CYA on that.
Ford is not saying that. It's an industry wide standard. NHTSA says it and USTMA agrees and says it.

Some publications will come right out and say; "do not air down your tires"!
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Old 11-30-2020, 01:08 PM   #40
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