LT versus ST tires on a trailer

[91Excella]

After reading all the discussions, I was beginning to feel a little concerned about my use of LT 235-75-15-D rated radials on my trailer. So to be safe, I emailed Goodyear/Dunlop and Cooper Tires asking if the use of ST tires was important as a safety issue or just because of the extra UV inhibitors. I have yet to hear back from Cooper Tire, but Goodyear/ Dunlop's written response to me today, 15 August 02, was:

"Thank you for contacting our website. To address your concerns; a special trailer tire is not a must, the factor to consider is the load carrying capacity. If the Trailer does not overload the tire(s) then they are acceptable."

Of course everyone may still have their own opinion, but it's a fair bet that Goodyear/ Dunlop would not risk a class action lawsuit these days by putting this in writing unless their engineers were very certain of the safety of putting LT tires on trailers. If I hear back from Cooper Tire, I will post that, also. Thanks. - Guy

[83Excella]

I think the person from Goodyear/Dunlop who replied to you does not know a tire from a donut, there is a difference and to the majority or trailer owners it's a big one when factoring in safety on the road which should be top priority but often is not when pulling a trailer. I would not bet the safety of my family, trailer and truck based on what that person wrote. I suggest reading the tire article in this months Trailer Life as I posted earlier.

John

[cesurman]

The September 2002 issue of Trailer Life magazine has a very
comprehensive article on trailer tires. The subject of LT verses
ST is discussed at some length. It is their opinion that ST is the
better choice. Load range is another important factor. Most of the people I know have gone from load range C to load range D on the Goodyear Marathon tires on their Airstream trailers.
cesurman

[uwe]

I am with John on the safety issue, no doubt. But here is my experience with the ST/LT tire issue:

Ordered Carlisle TRAILER tires from a local tire store. Size 7-15, bias ply,load range C. Tires came in, were installed and I took a trip to Baja California the next day. Everything worked most excellent.
While down there, noticed the LT rating on the sidewall. got back, and called my dealer. they apologized, ofered to replace the tires and ordered new ones. Again, LT on the sidewall. We left matters alone, did not replace the tires.
I called Carlisle tire on this. 3 times, spoke to different people every time. I found out that THEIR LT and ST tires are the same. I want to emphasize that I went with the original tall bias ply tires, not Radials. It is possible that the rules change on the ratings for radial tires. I did not want to use the radials, because the recommendet replacement size to 7-15 is too small for my uses. i need ground clearance to get out of my parking lot and over the beaches in Baja......
There seems to be big controversy on this subject, as well as on the wheel issues. It is my opinion that correct load rating, overall tire age/condition, correct size and inflation pressure is more important than Lt or ST on the sidewall.

[91Excella]

This seems to be a very controversial issue. I have been towing for about 30 years. This 76 Argosy for about 20 years. I have never used ST Tires. I ran Goodyear Wrangler Radials Asymetrical LT 245-70R-15 C rated tires for years without a problem. They were a tight fit because of the extra width, but there was no sway and the braking was great because of the extra rubber on the road. However, the low ground clearance was a problem in some campgrounds with the 70 series. I tried Pirelli Scorpians in a LT 235 75 15 in a C load rating and they swayed too much, so after 1 trip I sold them. The Pirellis seemed to favor a soft ride, probably good for SUVs rather than trucks. I have never tolerated any condition I consider questionable, safety-wise, as I am sure non of you would, either. So I spoke to my local Tire dealer and told him that I wanted overkill. A very stiff, tall, heavy duty tire, and he showed and recommended the Dunlop LT235 75R 15 in a D rated tire. These things are a real heavyduty commercial truck tire, they weigh a ton, are ugly (no white letters here) are rated to carry 2440 lbs each at 65 lbs (the whole trailer is maybe 4500Lbs) and the sidewall is so thick you would not know they are radials if it didn't say so. There is no sway and I have good ground clearance because they seem taller than most tires that size(also the 235 vs 225 adds height and capacity). I keep a good protectant on them to prevent checking, and I have had no problems whatsoever.
I would be real surprised if most tire companies invested the money in designing a tire carcass exclusively for recreational trailers. Playing with the amount of UV inhibitor is one thing, that's cheap, but engineering a carcass just for a small niche market like travel trailers when the company has millions of dollers invested in the engineering of a whole range of heavy duty truck tires already does not sound like an efficient use of R&D funds, to me. And as the recent tire debacles have demonstrated, tire companies do not like to spend money on tire reengineering if they consider it to be cost ineffective. - Guy

[Inland RV Center, In]

My towing days ended some time back.

I find it very interesting as to why some choose to out research Airstream, about many things, especially tires.

There are many tires available, some real cheap.

Wonder why Airstream has researched and now spends more money for the tires they use in current production, as well as several years past, on the Goodyear Marathons.

They certainly could find many other types and brands that are much cheaper.

Just maybe, they had and continue to have, a great concern for the safety and well being of their owners, and therefore choose a superior product.

Naw, can't be, surely they seek to maximize profit.

NOT TRUE!!!!

They have and always will have the concerns for their buyers safety.

It is some of us, who fail to see the merit of that belief, and as a result, sometimes, lean way over the edge.

Remember though, when you change the manufacturers specs, to something of your choice, and hurt someone in the process, you bite the entire bullet, when it comes to liability.


Andy
inlandrv.com
airstreamparts.com

[uwe]

Hey Andy,

There are plenty issues with Airstream to raise questions as such. If I put their "recommendet" size marathons on my 71 tradewind, then I'll need skid plates just to get out of the driveway where I keep the trailer. They are substantially lower than a 7-15.00 that came originally on the trailer. the 7-15 is the same height as the 245/75-16 on my van.
225/75/15 is very low in height, unfortunately. Probably safe, but certainly not fitting for the ride height of that era. This is not "outresearching" Airstream, but merely using common sense.
If they were so concerned as you state, then why don't they offer a correct size tire? Changing to the 225 Marathon would change the ORIGINAL tire size. I doubt they would stand behind any one of us in a lawsuit involving tire sizes and/or ratings.
Fact is, this Marathon tire size is so common, that they use it because it is a mass item, and most likely very cheap to them. My tires weren't particularly cheap, but one of few manufacturer's that made the right size. I would have bought the GoodYears, had they had the right size.

[91Excella]

Andy - I can see you have a great respect for Air Stream, and I do too. It is an excellent product made by an excellent company. However, when the factory researches a product, they cannot be single minded in that research, as an individual can. Sure, safety is a very important consideration to them. But also, the price and ability of the subcontractor to deliver the volume of tires needed on time are considerations which are equally important, as is picking a size which will fit the maximum number of different models. If these things were not all considered equally, Air Stream's "researcher" would be negligant in the performance of his job, and they would quickly go out of business. He is held accountable to the company and it's owners/ shareholders for all these things, not just safety. The "bottom line" is turning a fair profit, as is the "bottom line" for any successful business, even highly ethical, quality and safety oriented businesses like Air Stream; they are not running a charity. The Air Stream factory supplied my Argosy with a "C" rated bias-ply tire in the 225 size. They specified 40 lbs of air. This tire size at 50 lbs is only rated for 2150 lbs in a modern radial. I am "not " second guessing the factory specifications. I am considering the factory specifications to be my "minimum baseline", and in my estimation to be borderline safety wise, because the factory had to be eqally concerned with price and volume availability. Also, in 1976, 31 years ago, radial tire technology was not as advanced as it is today. I am using a modern, state of the art, Goodyear/ Dunlop Heavy Duty "Radial" Truck Tire in the "235" size which is "D" rated for 2450 lbs at 65 lbs. I run 50 lbs, not the 40 lbs the factory recommends. Two of these four tires will safely support the weight of the trailer with no caveats. It takes three of the original tires to support the trailer. My set-up is designed to exceed the factory specs and give me an extra margin of safety that would have been "uneconomical" to the factory. I do not have to be confined to a "price point", nor do I have to consider what size will fit the most different models of trailer. I am only concerned with putting the safest, strongest, best handling, best quality, most modern engineered, highest weight capacity tire available that will fit my trailer. I have written to Goodyear/Dunlop and they have confirmed in writing that the only safety item to be concerned with between LT and ST tires on a trailer is load capacity vs trailer weight. The representative who answered my query would not say this without consultation with both the engineering and legal departments at Goodyear/ Dunlop. Writing to me is "preventive medicine" for their engineering and legal departments as far as liability is concerned. I have not received the September "Trailer Life" in the mail yet, but I will certainly read it when it arrives and seriously and respectfully consider their perspective, also, as I am seriously and respectfully considering yours. I greatly appreciate your opinion, and will take a new look at the ST tires available to fit my trailer the next time I shop for tires. But I will not compromise my safety by going to a "lower" capacity tire than I have now. I want the safest tires available, by my research, at any price. Thanks - Guy

[Inland RV Center, In]

Uwe.
If you have low clearance, I would suggest you check the axles. There are many failures with the pure rubber rods from 74 on back.

Guy.
There is a difference between the LT's and the ST's. The ST's have a much greater sidewall construction. LT's cannot take the sidewall twisting that happens when a tight turn is made, nearly as well as the ST's.

Andy
inlandrv.com
airstreamparts.com

[83Excella]

Obviously a very debatable topic on both sides, I think the important thing is as long as you are making an informed decision between ST & LT and you are aware of the differences between them it comes down to a matter of preference for the user, but I think it is important for owners to know the difference between the two and make the right decision & not just pick a LT tire because someone told them it was ok to use it, remember salespeople are professional liars and they are paid to lie they could care less about your safety or selling you the right product for the right application, same thing with buying hitches and tow wehicles, their bottom line is 'will that be cash or charge'.

John

[uwe]

Andy,
I don't have low clearance with the tall bias ply tires that apparently came on the trailer originally. I get along so far. This is not to say that my axles shouldn't be checked soon. I will come and see you guys as soon as your summer rush slows down a little bit.

[Inland RV Center, In]

John.
You hit the nail right on the head.
Sales people don't get involved with helping someone in trouble because of their advice.
Cash or charge, "IS" their byline.


Andy
inlandrv.com
airstreamparts.com

[Action]

I bought a 27' boat that came with a brand new dual axle trailer and ST tires. The dealer had it delivered from CA to my home in AZ.

The delivery company replaced a tire enroute to my home. I had tread seperation on the 3 other tires with in 2.5 years. After checking the load range (C) I discovered that the tires were only rated for 1870# at max inflation. 4 wheel times 1870 = 7480 #'s. My towed load was 7500.

I guess it's too many things going on for that dealer to get my next sale. That was my 3rd boat and it cost $47,000. There will be a next one. So the "cash or charge byline" does not make for repeat sales! I dislike going back. So I just go away.

>>>>>>>>>>>>>>>>Action

[91Excella]

I said I would report what response I got from Cooper Tires on the ST vs LT issue. Here goes. Cooper sent me an email with a phone number to call. The customer service rep at the number put me on hold and got a gentleman to talk to me who has years of experience actually building the tires and is a trailerist, also. Yes, there is a definite difference between Cooper LT and ST tires.
However, it is not a "safety" difference as long as the load rating is correct for your trailer's gross weight when towed. Both ST and LT tires can be safely used for trailers. The difference in construction is this: Cooper ST tires are basically a tire that combines passenger car tire construction techniques, with heavy duty truck tire fabric and cord materiels. This results in an ST tire having a high LT type load rating with the lower air pressure requirements and soft, shock absorbing sidewalls of a passenger tire. There is also extra UV inhibitors and oils added to the rubber to help in storage. This is much easier on the suspension and other components of the trailer on bumpy roads than the stiff sidewalls and higher air pressure of the LT tires. As far as tire safety is concerned, he stated that is up to the trailerist and how he maintains the tires, keeping the proper air pressure in the tires, and choosing the correct load rating. He stated LT tires have an advantage because of the larger choice of tread patterns and number of sizes available to choose from to suit the conditions you are towing in, such as snow, unimproved roads, etc. He also stated that it is imperative to not allow the trailer to rest on the tires in the same spot for months at a time in the off-season. This causes the fabric cords in the tire to take on a flat "set" which can then cause some of them to actually break apart when you next take the trailer out on the highway. This can cause complete tire failure. He stated the best thing to do is to store the trailer on jacks with the tires in the air, or removed completely. This last information was of concern to me since I only have "stabilizing" jacks and cannot lift the trailer enough to take the load off the tires without serious effort. At any rate, that is what Cooper Tires has to say on this subject.

[uwe]

Hi 76Argosy,
Thanks for the Cooper article. The trailer life article on tires in the Sept. issue states similar facts.
How about those safety jack stands they sell all over the place? You can use them to lift your trailer and keep it in the air safely.I guess it would be a good idea to find out where the best for support is for long term storage, so as to not bend the frame rails.

[BobbyW]

76Argosy:

Thanks for taking the extra time and effort to contact Cooper Tires and then taking the time to post a carefully edited thread with your discoveries. This is what the AirstreamForums is all about. Sharing great information with each other.

I would also like to encourage you to take a little more time to email a thank-you to Cooper Tires customer service and mention the good information and service the tire specialist gave you. I know they like to hear good feedback as well as bad. Maybe it will sell a few more tires for them. This link shows the history of the company. Kind of interesting. http://www.coopertire.com/about/history/index.html

-BobbyWright

[91Excella]

BobbyWright -
Thanks for the kind words and the link to the history of Cooper. It was interesting. I will send that E-Mail thank-you to Cooper, as you suggested. - Guy

[jsvetrano]

My trailer is an enclosed Homesteader 6x12 single axle used for toy hauling & utility purposes. Rather than replace with 205/75/15 Carlisle Radial Trails, I opted for LT 215/75/15 Yokohama Geolander's load range C. I did so for two reasons: Higher speed rating and matching tread pattern on both my truck and trailer. No problems after about 1500 miles so far. Trailer tires are prone to blowouts if you drive over 65mph especially in the summer when most people use their trailers.

[Wingeezer]

Originally Posted by 76Argosy

I said I would report what response I got from Cooper Tires on the ST vs LT issue. Here goes. Cooper sent me an email with a phone number to call. The customer service rep at the number put me on hold and got a gentleman to talk to me who has years of experience actually building the tires and is a trailerist, also. Yes, there is a definite difference between Cooper LT and ST tires.
However, it is not a "safety" difference as long as the load rating is correct for your trailer's gross weight when towed. Both ST and LT tires can be safely used for trailers. The difference in construction is this: Cooper ST tires are basically a tire that combines passenger car tire construction techniques, with heavy duty truck tire fabric and cord materiels. This results in an ST tire having a high LT type load rating with the lower air pressure requirements and soft, shock absorbing sidewalls of a passenger tire. There is also extra UV inhibitors and oils added to the rubber to help in storage. This is much easier on the suspension and other components of the trailer on bumpy roads than the stiff sidewalls and higher air pressure of the LT tires. As far as tire safety is concerned, he stated that is up to the trailerist and how he maintains the tires, keeping the proper air pressure in the tires, and choosing the correct load rating. He stated LT tires have an advantage because of the larger choice of tread patterns and number of sizes available to choose from to suit the conditions you are towing in, such as snow, unimproved roads, etc. He also stated that it is imperative to not allow the trailer to rest on the tires in the same spot for months at a time in the off-season. This causes the fabric cords in the tire to take on a flat "set" which can then cause some of them to actually break apart when you next take the trailer out on the highway. This can cause complete tire failure. He stated the best thing to do is to store the trailer on jacks with the tires in the air, or removed completely. This last information was of concern to me since I only have "stabilizing" jacks and cannot lift the trailer enough to take the load off the tires without serious effort. At any rate, that is what Cooper Tires has to say on this subject.

But are not Cooper's comments about ST tires having "soft shock absorbing sidewalls of a passenger type tire" the opposite of what Andy is saying about ST tires having "Greater sidewall strength" to cope with the side loads of turning a dual axle trailer?

All so confusing! What Andy has said is more typical of the comparative comments I have read elsewhere.

Having said that, I have so far been extremely happy with the 16"LT tires I put on last year to replace my 15" ST's !

Hoping that will continue, but this is indeed a controversial subject, and my fingers are still crossed hoping I will not later regret making the switch!

I have to admit that my decision was based largely on other folks experience as reported on this forum - that, combined with my own less than stellar experience with ST tires!


Brian.