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CWG 08-30-2016 08:20 AM

ST to LT Tires
 
I am a bit confused with the debate of ST tires and LT tires on RV wheels. I have read all the dealer information, independent reviews and different forums and it appears that the manufactures and majority independent tire reviews all differ with the common thinking on the RV forums that LT tires will be a safer option. ST tires area manufactured with strong sidewalls, feature materials and construction designed to meet the higher load requirements and demands trailer towing presents. Overloaded tires, Over & under-inflated tires and Improper weight distribution are reported the main causes ST blowouts and I wonder if that is not the same for LT tires? I monitor my ST tires for wear, maintain proper nitrogen pressure and use a TMPS but is it enough from information gathered here and on other forums by experienced people who have real life experiences. I have been RVing since the seventies and have been lucky so far I guess.

donniedu 08-30-2016 09:09 AM

ST tires have extremely soft side walls. Just go to a tire dealer and check for yourself. ST tires size for size weight much less than a comparable size LT tire. ST tires are tested to a much lower standard than other tire types. That is one of the reasons they can get a higher load rating.

TURBS 08-30-2016 10:16 AM

Bombdoc has had LT tires on his rig for two years !



2015 Columbus 320RS
2008 2500HD Duramax
2015 nights camped "34"
2016 nights camped "32"

M109Rrider 08-30-2016 10:53 AM

Quote:

Originally Posted by donniedu (Post 1304305)
ST tires have extremely soft side walls. Just go to a tire dealer and check for yourself. ST tires size for size weight much less than a comparable size LT tire. ST tires are tested to a much lower standard than other tire types. That is one of the reasons they can get a higher load rating.

When had my LT's mounted I compared the ST's just removed to what was being installed. Couldn't agree more, unbelievable difference. I wouldn't put an ST from any manufacturer on a little red wagon and pull it across the yard let alone put one back on my camper.

M109Rrider 08-30-2016 10:58 AM

1 Attachment(s)
3 years since this happened. LT's ever since

BombDoc 08-30-2016 11:06 AM

Like TURBS said, I've been towing with LT's for a couple years. I had them balanced when installed and noticed a smoother ride instantly. I use a TPMS and Check pressure often. Haven't had an issue yet. I went with LT's due to speed rating. I wanted something that I could rely on to do 70mph when needed. I don't drive 70 very often, but coming down the mountains in TN, having a blowout due to exceeding the manufacturers recommended speed rating isn't something I worry about. 2 plus years on these LT's and I'd do it again.....so far.


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Tireman9 08-30-2016 11:08 AM

People do not seem to realize that it is the air pressure that carries the load not the tire construction. All the tire needs to do is to hold the air pressure. ST tires are "rated" to carry more load than an LT tire of the same size with the same inflation because:
1. The standards for ST tires were set when trailers were single axle 15' units driving at 50 mph max

2. RV industry fought hard to prevent ST tires from having to meet the update test requirements all Passenger & LT tires had to pass starting in 2002 so yes LT tires have to be better than ST tires because they are tested to a higher standard.

3. Multi-axle trailers place significantly higher shear force loads on the radial belts so the service on such trailers is tougher than on a motorized RV. With this engineering fact in mind a strong argument could be made that ST tires might need to be de-rated by 10 to 20% when placed on multi-axle trailers but again see #2 above.
This force is called "Interply Shear" you can google the term as it relates to tires to learn the science behind this fact.

To the OP, you said you reviewed many posts on ST tires. I might suggest you start reading my blog to learn what a tire engineer has to say about inflation, swapping tires, load etc.

Airdale 08-30-2016 01:45 PM

RV Trailer Tire Complexities

This topic is not as simple as it may appear. Can the trailer manufacture fit trailers with normal everyday Light Truck (LT) tires? Sure can. They can also use Passenger (P) or medium duty all position truck tires. However, Special Trailer (ST) tires were specifically designed for trailer axles. They have been around for more than 20+ years. Presently they are evolving rapidly.

Because most states don’t have laws that require tire monitoring, vehicle owners rely on retailers to provide them with tires that are safe for the normal operation of their vehicles when it comes replacement time. The automotive industry in collaboration with the Tire & Rim Association (TRA) provide listings of suitable replacement tires for all normal every-day vehicles. The tire industry has standards for plus sizing tires for your every-day vehicles. None of that applies to RV trailer tire fitments.

RV trailer tire fitments are the same in one respect, the vehicle manufacturer is solely responsible for the selection and fitment of tires to all vehicles they manufacturer. For RV trailer owners that becomes a complex problem. Few will take the time to study and understand the intricacies of the system and how it is all meshed together.

The most important factor after the fact of tire fitment is certification. This is where the vehicle manufacturer swears to the National Highway Transportation Safety Administration(NHTSA) that the tire fitments depicted on the vehicle certification label are appropriate for that vehicle as long as the recommended inflation pressures are maintained as a minimum requirement. In doing so, the trailer manufacturer has taken the tire manufacturer off the hook - so to speak - of responsibility, as long as the tire has been properly manufactured and has no defects.

Therein lies the dilemma for trailer owners and tire retailers. There are no lists for suitable replacement tires for the RV trailer. Tire designs that differ from the Original Equipment (OE) tire design are not considered appropriate unless they are on the vehicle manufacturer’s optional equipment list for that trailer. The trailer’s owner’s manual is required to have a tire safety section. That section is going to tell the trailer owner to seek recommendations from the vehicle manufacturer for replacement tires. A follow-along statement may read “ use tires of the same size and load capacity as the OE tires“. Unbeknown to most vehicle owners is the fact that ST235/80R16E is a complete tire size. The ST locks in the appropriate tire design. The suffix “E” locks in the load range of the tire.

Tire manufacturers’ retailers are going to be very reluctant to replace the ST designed tire with any other tire design. Most trailer owners wanting to change designs will do so by buying the tire and having them installed by a tire installer unaware they are going to be used as replacements for another design.

Earlier I mentioned other designs. Some are unique and others are run-of-the-mill high production tires.

Passenger tires are currently being offered as options on some hi-end Airstream trailers. Evidentially Airstream feels they may be appropriate for their uniquely designed hi-end trailers.

A unique LT is often used as OEM by some trailer manufacturer’s for service on 7000# axles. Those LTs are specifically designed for trailer service.

Truck tires designed for low bed, high cube trailers are commonly found as OEM on trailers with 8000# axles. Some of them are European designs and only have a 62 MPH speed rating. If you want to travel at interstate highway speeds you will want to avid those 62 MPH tires.

Most of the major tire manufacturers have in their tire warranty packages a section labeled “things not covered”. In that section you will find a statement about misapplication. Almost always that is going to mean your warranty will be voided if you replace OEM ST tires with any other design.

Currently there is very little excuse for not using ST tires to replace OEM ST tires. Soon all ST tires coming in from off shore manufacturers will have speed ratings on their sidewalls. Those ratings will always be higher than 65 MPH and seem to be leveling off in the 75 - 81 MPH range. All of the smaller ST tires in sizes 12” - 15” have a wide range of load capacity selections. A lot of the 15” tires now have a LRE in their desired load capacities. The 16” tires range from 3000# of load capacity to 4080# of load capacity.

There is not much name brand loyalty among trailer owners, so ST tire manufacturers are often changing names for some reason or another. Sometimes vehicle manufacturers use borderline load capacities that cause the OE tires to have a very short life span and give the brand a bad reputation. Not to worry, the name will be changed. Sometimes ST tires that are cheep, 100% cheep, not to worry, their name will change.

I guess the bottom line is tire manufacturers are going to go along with the vehicle manufacturers and not get into a long legal battle with them which they will surely lose because NHTSA stands with the Vehicle Manufacturers.

donniedu 08-30-2016 02:26 PM

Nice writeup Airdale. But you failed to look at one, and probably the most inportant aspect of all this. COST! Trailer mfgs are always looking to squeeze maximum profit from each unit built. ST tires they install probably cost them 50 to 60 dollars each. To install a more substantial LT tire would likely cost them more than a hundred dollars each. That means 200 dollars less profit per unit out the door! In 2005 my fiver came from the factory with an LT tire. They served me very well for 6 years, never a blow out, no tread seperation, no loss of pressure, nothing! Would I install a ST tire, just because they come on newer trailer of the same maker? Heck no! I may be dumb, but Im not stupid. My current LT tires are going on 6 years old and still go down the road with no issues. Given the state of ST tire manufacturing and where they are made (China) with little to no quality control, I cannot in good concencious suggest them to anyone.

M109Rrider 08-30-2016 03:03 PM

I think I have a pretty good grasp on the load bearing properties of air. I've been driving 300,000+ lb hovercraft on a cushion of air in the Navy for the last 14 years. The battle is keeping the air IN the tire. I can fill a basket ball to 80 psi, that doesnt mean I can put it under a 10k camper and expect it not to pop. The if the tire isn't substantial enough to hold the air in under less than perfect conditions then it's worthless.

Tireman9 08-30-2016 03:56 PM

Airdale, You and I agree on many things. One is that the "Original" selection of a tire is the responsibility of the RV company. However IMO if the RV company isn't willing to accept the responsibility for their selection and to stand behind the components they select for much longer than it takes to drive off the RV dealer sales lot, then I see no reason for users who want more reliable tires or refrigerators or brake lights to not be able to change those components.

Technically as long as the replacement tires are rated for the same or greater load and speed capacity than the OE tire then I would challenge the concept that the owner should not change tires simply because they aren't the same as the OE component.

IMO the "Unsuitable for application" is simply a phrase used to get out of having to warranty a tire that has failed due to overload or under-inflation. I would be willing to challenge another tire engineer on what facts would make an application "unsuitable" as long as load and speed ratings of the replacement tire exceeded the OE tire.

As we both know the revised FMVSS regulations 571.139 and the other updated requirements that apply to Passenger & LT type tires require significantly more robust design for tires than the 30 year old 571.109. As such I feel that using tires that can pass 139 as well as provide more load and speed capacity than 109 would be a more reasonable choice.

If or whenever an RV company decides to demonstrate confidence in their selection of tires for the RVs they are selling by offering meaningful warranty policy I would of course then be willing to change my opinion

Tireman9 08-30-2016 04:01 PM

Quote:

Originally Posted by M109Rrider (Post 1304447)
3 years since this happened. LT's ever since

That failure appears to be a Tread separation which is the result of poor or degraded tear resistance between the top belt and the undertread compound.
This is clearly not a Run Low Flex "Blowout"
I agree that an LT tire with higher load capacity & speed rating would probably be more reliable than an ST type tire. Especially as with LT you have the option of selecting tires made by "Tier 1, 2 or 3" level tire companies rather than "container babys" from tier 5 company.

rattleNsmoke 08-30-2016 04:09 PM

My 2010 Cedar Creek 34SATS gross weight is approx 14,000 lbs. I bought The Beast 1 year old and it came with ST 'BlowMax' china bomb tires. What's weird is the trailer is factory placarded for 235\16 LT's. After a thousand miles I yanked the china bombs, gave them to a buddy with a lighter weight trailer with a stern warning that I took NO responsibility what-so-ever for their reliability and tossed 4 Cooper LT SRM II's on The Beast. The second season, my buddy had two tire failures with the last one wasting his fender skirt and flooring. He switched over to Cooper LT's and never looked back.

Tireman9 08-30-2016 05:56 PM

Quote:

Originally Posted by rattleNsmoke (Post 1304746)
My 2010 Cedar Creek 34SATS gross weight is approx 14,000 lbs. I bought The Beast 1 year old and it came with ST 'BlowMax' china bomb tires. What's weird is the trailer is factory placarded for 235\16 LT's. After a thousand miles I yanked the china bombs, gave them to a buddy with a lighter weight trailer with a stern warning that I took NO responsibility what-so-ever for their reliability and tossed 4 Cooper LT SRM II's on The Beast. The second season, my buddy had two tire failures with the last one wasting his fender skirt and flooring. He switched over to Cooper LT's and never looked back.


Well clearly your TT is just another example of the outstanding job FR does in selecting tires for application on their RVs. Too bad you didn't discover the tire situation when new. You could have filed complaint with NHTSA and you could have demanded FR give you the LT their tire placard identified. Have you confirmed if there were other mistakes? such as axles not matching the GAWR on the Certification sticker?

IMO some want to say the RV company is the one responsible for selecting the correct tire but clearly FR doesn't take that job seriously or they would not be having all the recalls and other problems with tire size and placard information. It is as if all they care about is making the sale then "buyer beware"

rattleNsmoke 08-30-2016 06:54 PM

I doubt that would fly Tireman. As mentioned I bought The Beast as a one yr old unit. It was used. To complicate matters, I got it from an Airstream dealer, not even a FR distributor. Prior to this fifth wheel we owned a 30 ft. Jayco aluminum sided non-slide out TT that we hauled 3 kids all up and down the East coast on 15" Goodyear Marathon ST's incident free. The TT grossed out at around 7600 lbs. Had I been aware of all the issues with PowerKing 'Blowmax' tires especially on heavier trailers I would have demanded the correct tire installed prior to signing on the dotted line. I betcha he pulled the LT's off my trailer when they got it to put on one of theirs, and installed those junkers. I guess it's live and learn. :(

Oaklevel 08-30-2016 07:16 PM

Check with your tire dealer first as well. The tire dealers that I deal with here in my area will NOT put LT tires on trailers and trailer rims unless they came with them. I can only assume that they do not want the liability. :eek:

:campfire:

Iwannacamp 08-30-2016 07:21 PM

Ok. Color me stupid. Is there a 15" tire in LT that will handle 2500-3000lbs per? I have kinda looked, but I haven't seen any.


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325BH 08-30-2016 07:49 PM

Quote:

Originally Posted by Iwannacamp (Post 1304878)
Ok. Color me stupid. Is there a 15" tire in LT that will handle 2500-3000lbs per? I have kinda looked, but I haven't seen any.


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I don't think so. I upgraded to 16" wheels to get an LT tire with a rating a bit higher than the 15" ST's they were replacing.

The problem people seem to miss is: the higher ratings that all these ST's have mean absolutely nothing since they keep blowing up. I would bet a lower rated LT could carry more than a higher rated ST and outlast them. I wouldn't recommend it, but I bet it would.

I upgraded to 16" wheels and got 16" LT's with a higher rating than my 15" ST's.

I honestly laugh at all the ST defenders parroting how they are designed for the special forces trailers exert. Many LT tires are suitable for any location (front, rear, trailer). You can bet your ***** the ratings on LT's are legit. I don't trust ST's at all. Pure garbage in my eyes.


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Skyliner 08-31-2016 12:36 AM

Have had on average 2 blowouts a year for past 8 years on ST tires on a variety of trailers.

I switched to LT tires this year and this was my first summer without a blowout.

ST tire advocates can keep their ST tires. I'll stick with my LT tires and keep watching for those elusive to find LT tire blew threads on the forum.

Witch Doctor 08-31-2016 02:22 AM

Quote:

Originally Posted by Oaklevel (Post 1304876)
Check with your tire dealer first as well. The tire dealers that I deal with here in my area will NOT put LT tires on trailers and trailer rims unless they came with them. I can only assume that they do not want the liability. :eek:

:campfire:

X'2 you will be hard pressed to find a dealer to install LT tires on a trailer when the sticker reads ST here in Virginia. So I looked for the best ST tire on the market. I switched to Maxxis 8008 "D" rated tires. I have been very happy with the out come and handling since. The only way I could have put on LT tires on would be to take each tire off and take it down to the tire shop and have them install them one by one. When I went to tire dealers the first thing they did was check the sticker on the trailer, mine says ST "C" rated. I was able to move up to "D" rated only without having to buy new rims to except "E" rated pressure. My rims are maxed out at 65 PSI stamped on them. Not all ST tires are bad. I don't here of to many complaints on here about the Maxxis ST 8008. It's a very good tire. I'm not worried about my speed rating of 65 because I don't hardly ever go over that speed anyway. The tires that came from the factory were called Trail Express. Try to find a dealer who can even get those no name tires, Noboby but Lion Head sells them. In fact even in NC where I had to put new tires on before going home from the Mayberry Rally also refused to sell me LT because he said the sticker says ST. and they couldn't put LT tires on because of the sticker.


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