ST vs LT tires.

Here are a 3 facts about the differences in the 2 types of tires.
A ST235/80R16/E Goodyear Marathon is 9.2” wide and 30.7” in diameter on a 6.5” rim. A LT235/85R16/E BFG Commercial T/A is 9.3” wide and 31.8” in diameter on a 6.5” rim.
A LT235/85R16/E gives up a little about 10% in load carrying capacity to the ST235/80R16/E.
A LT235/85R16/E has a speed rating about 50% higher than the ST235/80R16/E

Now opinion about the 3 facts above
While the difference in size is minimal, it should not be ignored. But I can’t recall anyone going from 235/80R16 to 235/85R16 having problems.

The loss of 10% of the load carrying capacity can be a problem, depends on GAWR. But an F or G range tire such as the G614 would solve that issue.

The difference in the speed rating is substantial. Speed makes heat, heat kills. This means that the LT either does not make as much heat, it withstands the heat better, or most likely some of each. If I am running down the road at 63 MPH on ST tires I am right at the limit. With the LT tires I’m only at 66%. This is a big difference.

But since the trailer manufacturer specifies the OME tire, the tire manufactures will not recommend a change of tire size and carrying capacity. They will not assume that liability. Like wise many retail chains will not install a tire that is not OEM spec. Like Fast Eagle says, it’s a misapplication.
The trailer manufacturer buys a legal tire at low cost. The tire manufacturers sell tires that are made at low cost. We sit on the side of the road with blown tires, or we find a better tire. Even if it does not meet factory specifications.

Treads come off LT tires to. Trailer tires get slid side ways so that pulls on the tread no matter what kind of tire you have. Its just LT tires aren't going to go boom just because your going 70 mph

john&bet wrote:

FastEagle wrote:

john&bet wrote:

JJBIRISH wrote:

I would like to know where this recommendation label is posted on my trailer as to what type of tire I must use,LT or ST, if it so critical. I can not find one.

On your trailer the certification label is supposed to be on the left forward exterior portion of the trailer. Probably just forward of the basement door or propane door.

All 2004 & 2005 Keystone trailers with 6000# GAWR axles came equipped with LT235/85R16E tires of various brands. Most of them had failure rates very similar to those trailers and axles fitted with ST235/80R16E tires in subsequent years. That is, of course, a subjective finding, based on my personal research.

FastEagle

Fast Eagle, That label, as I have said before does not list LT or ST only size, 235/85/16E. My manufacture does not make a recommendation as to LT or ST. Some day I might go to the trouble of posting a picture of it for you.

When your trailer was built the ST235/85R16E did not exist. Also, the new 2007 rules were not enacted requiring better descriptions on the certification label. The bottom line is, at that time, the 235/85R16E was the only tire built with that description and it was an LT tire.

FastEagle

DJ wrote:
I have a TT that has the tire plate info on it. It also only states tire size and load rating. It came brand new from the factory with LT's. So if I replace with ST's I'm opening myself up to a lawsuit?

Rather silly isn't it. Trailer mfg use P/LT and ST tires as OEM. And before the ST tire hit the streets we used nothing but P and LT tires (car or truck tires back then)
This thread on IRV2 website;

"Guys, after reading all the post I realized that I better get my owners manual out. The Goodyear Fortera tires were an option for the 2008 Domani. They came with a special chrome mag wheel from American Racing (8 lug 20 X 10" rim). The tire has a load range of 2756 lbs @ 50 psi. The axles are Dexter #11 Torflex rated at 5200 lbs. the manual also stated the importance of properly loading the unit before travel. The gross weight rating is 11,500 lbs.
The tires do not show a LT only the 285/50/R20 with a 116H. I think that contacting Goodyear is a great idea and I plan to do so.
I really appreciate all the input and it's amazing how much you can learn on this site. I just can't wait to get on the road. Thanks."

This poor guy, and probably other Domani owners that bit into using optional P tires on 5200 lb trailer axles now is in a pickle. The size tire Carriage selected is no longer made.
IMO he like the rest of us will find a savvy tire dealer and they will install another P or ST or LT of their choosing and give the owner their blessing with the usual mfg warranty.

kedanie wrote:


It's just a giant urination contest.

Keith

- - and the usual - "bird" - poop..:B

.

CapriRacer wrote:


In the case of ST tires, since there is virtually no commonality in tire size, it is easy for a tire manufacturer to avoid the pitfalls by stating that an LT tires is not a suitable replacement for an ST tire - and that would be correct since there is no tire size that directly corresponds.

But if certain factors are accounted for, then an LT tire COULD be used as a replacement - BUT - a tire manufacturer will want to shift the legal burden to the person making that decision and not take it on themselves.

this is completely true and worth repeating...
I do personally have a problem with the extent they will go to pass off that burden… combine that with the level of what is in my opinion misleading marketing of the ST tire that IMO crosses the threshold of lying, leaves me with a lot of distrust in anything they say industry wide…

JIMNLIN wrote:

JJ wrote:
JIMNLIN wrote:
Jack, I could respond in like to your usual personnel attacks but the OP requested we keep it civil.
personal attacks??? so responding to you accusation is a personal attack... ok if you say so...

I was referring to your comment that says : "Your argument doesn’t hold water, is laughable, and is really well below your personal knowledge about tires…".
IMO these are the type comments that the OP requested we refrain from using.

However...
Nice long reply and your to be commended on the length of research you must have done up into the night on the content. :B .....but nothing new in our/your word game for me to respond to.

Jim it just shows how different minds can so easily interpret things differently… I thought my comment was complementing your knowledge of tires which I do have a great respect for even when we disagree which happens all too often when we basically agree on so many of the details…

However I still don’t see my remark as a personal attack or that our disagreement as violating the OP’s request… we just disagree, you respond to my post, I respond to yours… that's how forums work…

could I have responded differently, better, or professionally??? Professionally no… differently or better I would have to say yes, on almost any and every post I write…

In my mind the tire companies are the professionals here and they fail to play that role on this topic… I see no reason or added liability to them to just explain how I should size a Wrangler tire to properly fit my trailer application, if I can… it would still be my decision on what tire I should go with, and all of their normal disclaimers are still in place and rock solid…

It took very little time or research to make my response since I was one of those you targeted with similar remarks… :B:B
actually other commitments more important don’t allow me to spend a lot of time researching and my connection to the internet is so poor the forum search function don’t work very well and often I can’t even connect to RV.net…

I don't get this whole "ST vesus LT" tire thing.

Plenty of heavy duty one-ton and one-and-a-half-ton trucks use "LT" tires. Why wouldn't a trailer or fifth wheel owner not eventually want LT tires of the proper size and load range on their towable??

What was the original purpose of "ST" tires anyway?: If it was to specify a heavier duty tire, than maybe pickup owners should put ST tires on their trucks instead of LT tires. If it was to offer a "cheaper" alternative for use on towables, then maybe towable owners should get rid of their ST tires and as soon as possibe put good old truck LT tires on their towables if they want the ultimate in ruggedness and safety.

My fifth wheel manufacturers owners manual states. Your trailer came with special trailer (ST) tires. Light truck (LT) tires may be used as an alternative. While Light Truck (LT) tires may be used, it is not recommended that the two different style of tires be mixed in usage. Use only ST or LT tires at the same time (including the spare).

Not that it matters to me. My towing experience has been poor with ST tires. And has been excellent with LT tires. I'll continue to use LT tires. And will continue not to use ST tires or Chinese tires of any type.

None of the so called internet drivel proclaiming the benefits of ST tires will trump my personal experiences.

ST tires may be engineered to withstand all the rigors of towing and heavy loads. But if they cannot be made to actually and reliably perform the task, then what good are they. I have had ST tire failures with ST tires made in USA as well as, China. Goodyear has paid for coach damages. But I would rather not have coach damages in the first place.

They can engineer all they want. But they cannot manufacture them to fulfill the engineering requirement. That is my experience. I'll not be buying any ST tires. I don't care what anyone tells me. It's my coach, my money, my family, and my experience.

JJ wrote:
JIMNLIN wrote:

Jack, I could respond in like to your usual personnel attacks but the OP requested we keep it civil.

personal attacks??? so responding to you accusation is a personal attack... ok if you say so...

I was referring to your comment that says : "Your argument doesn’t hold water, is laughable, and is really well below your personal knowledge about tires…".
IMO these are the type comments that the OP requested we refrain from using.

However...
Nice long reply and your to be commended on the length of research you must have done up into the night on the content. :B .....but nothing new in our/your word game for me to respond to.

flyinguy68 wrote:

JJBIRISH wrote:

flyinguy68 wrote:

JJBIRISH wrote:
It will have axle load rating (mine – 5040), rim size (15x6) and tire information (225x75xr15)PSI (65) and the trailers manufacture and VIN number… it MAY or MAY NOT use the Letter designations for the tire, but it don’t need to, because there are no LT tires in the size, weight, and PSI ratings listed for the trailer OE with the ST tire…

I have not here or ever before made a claim that you could not use a LT tire… but it seems people for the sake of argument read whatever they want into a post…

BTY You limiting factor seems to be your axle anyway not the tires… your OEM tires had a higher rating than your new ones, but both tires meet or exceed what I might consider as a marginal axle for a trailer that size…

now help me find on the manufactures website or catalogue, where your TransForce HT tires you installed are recommended or even a hint that that tire can or should replace your OE ST tire... and/or any OFFICIAL information from any tire manufacture stating that the LT tire is a good tradeoff for a OE ST tire...


Again some of these arguments are appropriate in the 5er forums, not too much in the TT forums, and need to be more specific as to trailer size in the general forums…

JJ is this what you are talking about? A tire manufacturer that is advertising an LT tire for trailer applications?
Link-> Goodyear

JJ I'm not sure what argument you are trying to make. As for me, just like my politics I am neutral middle of the road & independent.

Sorry for the delayed response… almost 4:30 and I need at least a few hours sleep…

That is a lonely example from GY of a LT tire being advertised for trailer use… other than the ST Marathon it is the only example in the GY stable… of course it is a LR G 110 PSI in 16 inch and is speed restricted all be it 75 and not 65 MPH with fitment only on the bigger 5er’s and possibly a few if any TT…
This is also why I said this argument has more merit in the 5er forum and not very much at all in the TT forums, and needs better explanation in the general forums…

But it does show there is no reason to not market any of the other LT tires, if in fact the mfg. believes they are a good for trailer fitments…

I have voiced no opinion in the ST/LT argument only questions that the mfg. won’t answer… and there is no official documentation to answer them… what documentation there is, mostly says not to use the LT for my trailer… I could post examples of that but it just causes more arguments even if it’s from the mfg…
I have been more critical of the ST and given my reasons why many times more than most, but have given my opinion that the Maxxis is the best ST tire and what I am using… I have also been very critical of Maxxis for their distribution system, so much so I even contacting them about it…

So again I ask why the tire manufactures duck and hide from a simple question like, can I use your model X LT tire on my TT…

The law says the tires must equal to or better than axle rating… OK, sounds reasonable to me…
why can’t/won’t the tire Mfg. say it so everyone is in agreement… I have already stated that I believe it is a liability issue, and the risk is high enough to the tire mfg. that they won’t accept it…

So If it’s a high enough risk that they won’t accept it, why should I accept it…

:h Quote "The law says the tires must be equal to or better than axle rating… OK, sounds reasonable to me…"

What more do you want? If you buy an LT tire that meets or exceeds your axle weight rating you are in compliance. It's seems pretty darn simple to me when you boil it down to just this. And from what I've read from both the ST & LT proponents. This is truly the ONLY requirement you must meet.

Flyinguy's bottom paragraph is the BOTTOM LINE!!!!! It can't get any simpler than that.

I have a TT that has the tire plate info on it. It also only states tire size and load rating. It came brand new from the factory with LT's. So if I replace with ST's I'm opening myself up to a lawsuit?

Good Grief!!! :R