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LT Tires


yzg

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Folks,

 

Am looking are replacing my ST tires with LTs..

 

Is there a list on this site that specifies brand/model/ size ? MIne are 235 80 r16 so I know I have to move up or down slightly for a LT..

 

I will be buying in Canada...

Thanx

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Michelin XPS Ribs or Commercial T/A All Season 2

 

These only come in size LT235/85R16.

 

 

First and foremost you must make sure that these tires will carry the actual loads.

Max Load for both is 3042 lbs @ 80 psi

Load Range E AKA 10 ply rating

 

Second you must make sure they can fit on the trailer. Not touch the tire on the other axle nor the wheel well when scrubbing or during suspension travel.

XPS Rib - OD 32.2"

Commercial T/A - 31.7"

 

If you have not had your trailer weighed by wheel position then this is a really good time to get it done.

 

Nothing worse than trying to buy a good tire only to find out its carrying capacity is less than what you actually carry.

 

Any tire will fail prematurely if overloaded. Good ones may last a few more miles.

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  • 2 weeks later...

Your trailer’s owner’s manual only recommends replacement tires of the same design and load capacity or something greater than that. The tire industry and NHTSA standards will tell us to use replacement tires equal to or larger in size/load capacity than the Original Equipment tires.

The ST235/80R16E tires are often difficult to replace with LT tires because of the large difference in their load capacities. The LT235/85R16G is the first size equal to the task and more often than not will also require new rims to meet the load capacity and air pressure for that LRG. However, there are more and more of them being offered and the price range is very wide.

 

Here is an example of how the fine print describes the fitment of the Michelin tire. Remember, the vehicle manufacturer fitted the OE tires to your trailer. Tire manufacturers risks are high if they fit something that wont carry the load equal to the OE tires.

 

 

https://www.michelinb2b.com/wps/b2bcontent/PDF/XPS_Rib_DataPg.pdf

 

 

The minimum load capacity of the ST235/80R16E is 3420# at 80 psi unless otherwise stated on the certification label/tire placard or in the trailer’s owner’s manual. That 3420# is your lad capacity target value for replacement tires.

 

 

FastEagle

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FastEagle,

 

To clarify since I have not heard or read this before, to upgrade from a ST235/80R16E to a LT235/85R16G, you will require new rims.

 

You point out that both require a 80 psi .

 

I don't see it pointed out in the brochure..what am I missing ?

 

Thanks

Ian.

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LT235/85R16 Load Range E which is what the Michelin XPS ribs are have a max load of 3042 lbs. @ 80 psi.max pressure

The XPS Ribs go no higher than Load Range E.

 

According to TRA (Tire and Rim Association) load inflation tables there could be manufactured somewhere a LT235/85R16 Load Range F or G (A completely different tire than the one being discussed) This theoretical tire would have a max load of 3750 lbs @ 110 psi.

Rims also have limitations either pressure and load or sometimes just load.

These rims specs are often stamped on the back of the rim and can be difficult to see when mounted.

Often the 16" rims that are on RVs are limited to 80 psi or a load <3500 lbs.

 

So, what Mark said is true for a LT235/85R16 with a Load Range G tire, but not for the particular tire(s) discussed.

 

XPS Ribs do not have a Load Range F or G option, so 110 psi would be irrelevant for this particular tire - Only Load Range E - 80 psi max.

 

As I stated before and was repeated in a following post. Before changing tire sizes one needs to be aware of the actual loads. Informed decisions can be made with factual data. The only way to do this is to have proper wheel position weighing. Often folks try to change to an LT tire from a ST tire which often has a higher load capacity. Then they get weighed and find that they are overloading these new LT tires. This is not good. There are good reasons to change to one of these options BUT these LT tires are not a good option if the loads do not allow for proper fitment or the wheel well or suspension or hub configuration do not allow for the change.

If a change is desired and the option is going to a lower capacity tire then getting weighed by wheel position is critically important or the situation could be worse than before. And the supposedly better tire is not better at all.

 

You do not want a tire where the actual load is at or near the max capacity of the tire.

 

If the loads are approaching 2800 lbs then there are other options but they are more costly.

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A LT235/85R16 requires a 110 psi rim to inflate it to full pressure.

 

You can run them at 80 psi if that provides enough load capacity.

 

 

So, what Mark said is true for a LT235/85R16 with a Load Range G tire, but not for the particular tire(s) discussed.

 

 

We ran into this when I wanted to get rid of the China "bombs" that were on the trailer. We decided on the Goodyear G614 RST. While it is sized as an LT tire, Goodyear states that it is designed for a fifth wheel or travel trailer. They are a load range G tire. Discount Tire, where we purchased them did their due diligence and contacted the wheel manufacturer to see what the psi and load rating was for the wheels, since it was not stamped on the wheels. They included a printout of that info with the paperwork so there is no question of suitability.

 

We have been pleased with the tires. First of all, they are made in the USA (Topeka, KS). The trailer tows better with the heavier duty tire, it tracks better, especially in crosswind conditions. And lastly, perhaps most importantly, if there is a tire failure, Goodyear will not only replace the tire but they will also pay for any damages to the trailer caused by the failure.

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The quote below is from the fine print in the Michelin reference previously posted. Michelin’s references are seldom to the point. They assume readers know about tire industry standards and will comply with them . Or, they are not willing to say anything that will relieve the vehicle manufacturer’s from their responsibility.

 

“To ensure correct pressure and vehicle load, refer to vehicle owner’s manual or tire information placard in the vehicle. Before mixing types of tires in any configuration on any vehicle, be sure to check the vehicle owner’s manual for recommendations.”

 

None of Michelin’s tires, 16” in diameter or less are manufactured for or touted as trailer tires. When reading Michelin instructions/recommendations for such tires you are reading things directed at the automotive tire market. Some are not necessarily compatible with the RV trailer industry.

 

The Goodyear G614 tire is unique in many ways. The rim width requirement is often overlooked. The G614 has a single rim width requirement, 6 and ½”. Because others have used them on 6” rims successfully does not make it safe. However, in the world of vehicle manufacturing the bottom line can be drawn by the individual trailer manufacturer. In other words, it they approve the use of a 6” wide rim for the G614 that recommendation then becomes their responsibility. They won’t do that lightly or without research.

 

Other tires the same size as the G614, with polyester casings, have rim width ranges of 6” - 7”.

 

FastEagle

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My 5th wheel has 235/85R16G tires I'm confused regarding min/max air pressure. The tire has 110PSI & I'm told that is 'cold' pressure. My air gage indicates 95PSI in the tires. My gvw is: 15,500 & I've had it weighed. Should I be running at 110PSI? someone said a minimum of 80 PSI, but that would probably be for less weight correct? I've got to do something, I noticed one of the tires is 'cupping' & It's the same tire I had a similar problem with once before. Appreciate any feed back.

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The tire industry term “plus sizing” fit’s the situation when going from ST235/80R16E tires to LT235/85R16G tires. Sometimes you will find manufacturers building ST235/85R16G tires with the same specs as the LT tire. Some others also make the LT with a steel casing. The most popular LT235/85R16G tire is the Goodyear G614 steel cased tire manufactured strictly for trailer axle service. (They can also be found with polyester casing).

The RV trailer manufacturer sets the standard for plus sizing with their Original Equipment (OE) tires. Properly trained installers will follow the following abbreviated description.

The first stop an installer will make is the trailers certification label/tire placard. From it they will get the size of the OE tires and their recommended air pressure. The dimensions of the OE tire will be compared to dimensions of the desired replacement tire. The larger dimensions must be able to fit into the wheelwell without any obstructions under normal vehicle operations. Clearances between tires on multiaxle trailers must be checked for minimum clearances (1” or more). Most often plus sized tires will require new rims that will withstand the higher load capacities/air pressure requirements of the replacement tires.

Once the new tire & rim assemblies are fitted to the trailer a new recommended air pressure will have to be set. The proper procedure for that is to determine how much load capacity the OE tires were providing. Let’s say they were providing 3420# at 80 psi - as per the tire placard. That 3420# is the minimum target value for the replacement tires. The installer would then use the load inflation chart for the replacement tires to find the psi required for them to provide the needed load capacity.

He is not done yet. The installer should make a notation in the trailer’s owners manual with the new tire size and recommended air pressure (s). Auxiliary tire placards are approved for the plus sizing procedure. The installer should make one depicting the new tire size and recommended air pressure and place it adjacent to the original tire placard.

FastEagle

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I research and write about RV tires in numerous RV forums and have a blog where I post in more detail. Many readers are skeptical about many of my post for some reason or another but mostly with my directness.

 

Nowhere in the tire industry standards is there a provision for inflating RV tires on motorized or trailer vehicles to the weight carried on the heaviest end of an axle unless that inflation pressure is equal to or greater than the recommended inflation pressure established by the vehicle manufacturer and depicted on the vehicle’s certification label, tire placard or in it’s owners manual.

 

Here are two references from well known tire manufacturers that support those statements. They are lengthy but well worth reading to those that want to know or are skeptical.

 

http://toyotires.com/sites/default/files/page-files/RV_tire_safety.pdf

http://www.trucktires.com/bridgestone/us_eng/press/zip/WeighForm.pdf

 

Those references will answer many questions pondered in this thread.

 

 

 

FastEagle

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  • 3 weeks later...

Another option would be 19.5" tires. You would have to get wheels. They are all steel and the weight rating are much better than the 16". The height of the tire is about the same as the 16" tire. The truckers use them a lot on low profile trailers often used with heavy haul and equipment haul trailers. I have used them on low profile tractors and I now use them on my MH.

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