3Fivers51 wrote: I just remembered this too, The tire dealer also said that the sidewalls in the ST were better than those in the LT and I mentioned this to my friend that has a diesel pusher and he had heard that was correct too. But everything I am getting feed back on seems to lead me to the LT. Don't know what luck I will have at this tire shop convincing them to put the LT's on for me.
Thanks,
Bill
It is kind of a moot point with your size tire isn't it. All that is necesary is to install a tire that meets or exceeds the needs shown by GAWR on your Federal Certificate Decal. Federal Certificate is on front lower left sidewall of trailer.
"3Fivers51" -
IMO - you and the tire dealer have an inseparable bond!.
It appears no amount of advice will counter the: "he says".
Sooooo - easy solution!.
Follow the advice above - skip what you have seen here - buy tires from your tire dealer that *meet spec* - and be done with it..
If they last - excellent!!
If not - you can add your .02 to the pro and con.
BTW - I began using 15" LT tires on TTs in the early 1980's - long before the internet, forums, or blogs.
Wasn't hard to determine they were a better way to go.
And . . . never bothered - or thought to ask a tire dealer's opinion.
Ran them all over the USA on a TT - with never a flat or failure.
ExRocketScientist wrote: The cords in the sidewalls of ST tires are larger than those in LT tires. This is why when you compare an ST tire to an LT tire where the physical dimensions are the same, the ST tire will have a higher load rating at a lower air pressure than the LT tire.
That said, look at the load rating. When you compare an ST tire of one load rating to an LT tire of similar load rating, the LT tire will usually maintain that load rating under more severe service conditions. The word "usually" here is my opinion and deserves some explanation. It all goes back to what I said about the difference in the testing standards. It is my gut feeling that most tires are built to barely meet the DOT specifications for the type with notable exceptions like the Maxxis M8008 (ST tire), the Michelin XPS Rib (steel carcass LT), and Bridgestone Duravis R250 (steel carcass LT).
The other thing you will notice about the comparison of the ST and LT tire with similar weight ratings is the LT tire will be physically bigger and the max inflation pressure with be 15 PSI higher. But just because the cords in the carcass of the ST tire will be larger, does not indicate it will handle significantly higher loads or be more durable than the LT tire WITH SIMILAR LOAD RATING. If it did handle significantly higher loads, you would not be comparing two tires with comparable load ratings (for instance, comparing the ST235/80R16LRE to the LT215/85R16LRE is not a valid comparison).
Why not just use the same sizes for comparisons? Like ST235/85R16E vs. LT235/85R16E.
All the materials required to build the tire is listed on each sidewall.
When looking at ST tires on a trailer and thinking "nice looking tires" you must remember the comparison ends right there.
If you structure a question to a Tire Manufacturer based on size/load range - you will always get FASTEAGLE's favorite "ST" replacement with "ST" response.
Structure your question based on GAWR won't limit the Tire Manufacturer response as much.
ExRocketScientist wrote: The cords in the sidewalls of ST tires are larger than those in LT tires. This is why when you compare an ST tire to an LT tire where the physical dimensions are the same, the ST tire will have a higher load rating at a lower air pressure than the LT tire.
That said, look at the load rating. When you compare an ST tire of one load rating to an LT tire of similar load rating, the LT tire will usually maintain that load rating under more severe service conditions. The word "usually" here is my opinion and deserves some explanation. It all goes back to what I said about the difference in the testing standards. It is my gut feeling that most tires are built to barely meet the DOT specifications for the type with notable exceptions like the Maxxis M8008 (ST tire), the Michelin XPS Rib (steel carcass LT), and Bridgestone Duravis R250 (steel carcass LT).
The other thing you will notice about the comparison of the ST and LT tire with similar weight ratings is the LT tire will be physically bigger and the max inflation pressure with be 15 PSI higher. But just because the cords in the carcass of the ST tire will be larger, does not indicate it will handle significantly higher loads or be more durable than the LT tire WITH SIMILAR LOAD RATING. If it did handle significantly higher loads, you would not be comparing two tires with comparable load ratings (for instance, comparing the ST235/80R16LRE to the LT215/85R16LRE is not a valid comparison).
Why not just use the same sizes for comparisons? Like ST235/85R16E vs. LT235/85R16E.
All the materials required to build the tire is listed on each sidewall.
When looking at ST tires on a trailer and thinking "nice looking tires" you must remember the comparison ends right there.
FastEagle
I think you missed my point FastEagle. When you compare the tires of the same size, the LT will have a lower load rating at a higher pressure than the ST. Some might consider that proof positive that the ST is a better tire and they should run ST tires. But if you will compare a slightly larger LT tire to that same ST tire, you can get a similar load rating. So now which is the better tire. Well I ask that the reader consider the difference in the circumstances under which the tire is required to meet that load rating. That is the difference in the testing the DOT requires for the two different tire types. When you factor that in, most would agree that the LT tire is the better tire.
If however, someone were to foolishly replace an ST tire with the same size LT tire, they could easily end up doing what you have warned many people on here to be careful that they don't do -- put a tire on that will immediately be overloaded all of the time. That would be a dangerous condition.
Where people typically take issue with your advice is the 6K axle that came with the ST tire that was most widely available (and therefore cheap because of economy of scale) and is therefore rated at 3500 pounds. You insist they must replace it with the same ST tire instead of one of the LT tires rated at 3042 pounds because the LT tires have lesser capacity. I will concede that perhaps in a few rare occasions the trailer manufacturer may be aware of some dynamics of the trailer that precludes the use of the lesser rated tire -- however all one has to do is recommend to the person to call the factory and ask why they put a tires one that together are rated to carry 1000 pounds more than the axle is. This will flesh out any dynamics issue as opposed to asking if it is OK to put the LTs on (if I were the manufacturer I would say NO, simply because I would not want questions from DOT after putting the ST tire specs on the placard on the side of the trailer).
I cant make much of a comment on most of this post because you got yourself going in circles a little bit. I recommend you do a little more reading of the DOT regulations and NHTSA safety standards so you can better tie the two together.
When you force an answer from a tire manufacturer or RV trailer manufacturer it will be “canned” if your question is precise. Here is an example: Email Michelin and ask them if their LT235/85R16E (any brand name) is a suitable replacement for an RV trailer with ST235/80R16E OE tires listed on the tire placard. Another example is to ask an RV manufacturer the same question about one of their trailers. If they were to recommend the lower load capacity tire their whole line of trailers equipped (OE) with the higher load capacity tires would be subject to recall.
Innuendos are often used and accepted here in the tire threads but in real life the bottom line will be determined by the facts and regulations that govern them.
We didn't upgrade to a 16" tire but rather we went up one load range to E rated tires and have not regretted it one bit. I now have the Maxxis 15" E rated ST tires and I am very satisfied.
Life is partly what we make it, and partly what it is made by the friends we choose.
ExRocketScientist wrote: The cords in the sidewalls of ST tires are larger than those in LT tires. This is why when you compare an ST tire to an LT tire where the physical dimensions are the same, the ST tire will have a higher load rating at a lower air pressure than the LT tire.
That said, look at the load rating. When you compare an ST tire of one load rating to an LT tire of similar load rating, the LT tire will usually maintain that load rating under more severe service conditions. The word "usually" here is my opinion and deserves some explanation. It all goes back to what I said about the difference in the testing standards. It is my gut feeling that most tires are built to barely meet the DOT specifications for the type with notable exceptions like the Maxxis M8008 (ST tire), the Michelin XPS Rib (steel carcass LT), and Bridgestone Duravis R250 (steel carcass LT).
The other thing you will notice about the comparison of the ST and LT tire with similar weight ratings is the LT tire will be physically bigger and the max inflation pressure with be 15 PSI higher. But just because the cords in the carcass of the ST tire will be larger, does not indicate it will handle significantly higher loads or be more durable than the LT tire WITH SIMILAR LOAD RATING. If it did handle significantly higher loads, you would not be comparing two tires with comparable load ratings (for instance, comparing the ST235/80R16LRE to the LT215/85R16LRE is not a valid comparison).
Why not just use the same sizes for comparisons? Like ST235/85R16E vs. LT235/85R16E.
All the materials required to build the tire is listed on each sidewall.
When looking at ST tires on a trailer and thinking "nice looking tires" you must remember the comparison ends right there.
FastEagle
I think you missed my point FastEagle. When you compare the tires of the same size, the LT will have a lower load rating at a higher pressure than the ST. Some might consider that proof positive that the ST is a better tire and they should run ST tires. But if you will compare a slightly larger LT tire to that same ST tire, you can get a similar load rating. So now which is the better tire. Well I ask that the reader consider the difference in the circumstances under which the tire is required to meet that load rating. That is the difference in the testing the DOT requires for the two different tire types. When you factor that in, most would agree that the LT tire is the better tire.
If however, someone were to foolishly replace an ST tire with the same size LT tire, they could easily end up doing what you have warned many people on here to be careful that they don't do -- put a tire on that will immediately be overloaded all of the time. That would be a dangerous condition.
Where people typically take issue with your advice is the 6K axle that came with the ST tire that was most widely available (and therefore cheap because of economy of scale) and is therefore rated at 3500 pounds. You insist they must replace it with the same ST tire instead of one of the LT tires rated at 3042 pounds because the LT tires have lesser capacity. I will concede that perhaps in a few rare occasions the trailer manufacturer may be aware of some dynamics of the trailer that precludes the use of the lesser rated tire -- however all one has to do is recommend to the person to call the factory and ask why they put a tires one that together are rated to carry 1000 pounds more than the axle is. This will flesh out any dynamics issue as opposed to asking if it is OK to put the LTs on (if I were the manufacturer I would say NO, simply because I would not want questions from DOT after putting the ST tire specs on the placard on the side of the trailer).
Structure your question based on GAWR won't limit the Tire Manufacturer response as much.
I don't think a tire manufacturer would answer that type of question. They don't build the vehicle. Maybe you should ask them...
FastEagle
I have many times in my past career in Fleet management & repair plus personal trailer applications. It is all about how the question is asked due to liability.
Where do you think I got confirmation of P-metric on light trailers with the use of the standard de-rate formula and the blessing of Bridgestone on using a M895 on trailer for the regional weather patterns seen in the PNW.
I have read the regulations as you have posted the link for me. A trailer manufacturer can put the LT on a 6K axle and has met the spec. And you did a very good job making my point. If you ask them about replacing the ST on that 6K axle with the LT you will get that canned response because of the rammifications. But what if you want to know whether or not the ST was to account for some dynamics of the trailer that required the extra 900+ pounds of tire capacity on the axle or was just a situation where it was cheaper for them? You could phrase the question as I said -- "Why does my 6K axles have 7K worth of load capacity in the tires?". If their answer was something like "to account for uneven side to side loading in crosswinds" I would say the LT is no longer a choice (3042 lb at 80 PSI) and there are other choices we have discussed at length. But what if their answer is "we were able to get volume pricing on that tire and thought our customer's would appreciate the increased reliability of a tire that was not running at maximum capacity". Then I would say go for the XPS Rib if you want to spend that kind of money. What say you?
Now when someone comes along with an axle greater than 6K and wants to put on an XPS Rib (even if they say I scaled my trailer at its maximum load and it weighed 13000 pounds with 2000 pounds of that on the pin), I'm with you on that one -- that is not something that should be done.
On the one hand is the RV trailer owners complaining about their trailer being equipped with barely minimum load capacity tires. On the other hand is the RV trailer owners wanting to replace OE tires with some load capacity reserves with tires that just barely meet the minimum DOT requirements. Without choosing sides let the regulations and safety standards speak for themselves. NHTSA says to use replacement tires with equal or increased load capacity. All major tire manufacturers have adopted that safety standard. They cannot control their retailers, only the knowledgeable buyer can do that by arming themselves with the safety information as it applies to their situation.
Load capacity reserves can only be obtained by using tires with sufficient excess load capacity. We are talking about tires here. They hold air. They are the must susceptible (risky) item in the “weakest link” scenario.
Do you have a TV with OE LT tires? Go out and take a look at the tire placard. Nice little bit of load capacity reserves there isn’t their?
FastEagle wrote: . . . snip . . . I cant make much of a comment on most of this post because you got yourself going in circles a little bit. I recommend you do a little more reading of the DOT regulations and NHTSA safety standards so you can better tie the two together.
When you force an answer from a tire manufacturer or RV trailer manufacturer it will be “canned” if your question is precise. Here is an example: Email Michelin and ask them if their LT235/85R16E (any brand name) is a suitable replacement for an RV trailer with ST235/80R16E OE tires listed on the tire placard. Another example is to ask an RV manufacturer the same question about one of their trailers. If they were to recommend the lower load capacity tire their whole line of trailers equipped (OE) with the higher load capacity tires would be subject to recall.
. . . snip . . .
FastEagle
I have read the regulations as you have posted the link for me. A trailer manufacturer can put the LT on a 6K axle and has met the spec. And you did a very good job making my point. If you ask them about replacing the ST on that 6K axle with the LT you will get that canned response because of the rammifications. But what if you want to know whether or not the ST was to account for some dynamics of the trailer that required the extra 900+ pounds of tire capacity on the axle or was just a situation where it was cheaper for them? You could phrase the question as I said -- "Why does my 6K axles have 7K worth of load capacity in the tires?". If their answer was something like "to account for uneven side to side loading in crosswinds" I would say the LT is no longer a choice (3042 lb at 80 PSI) and there are other choices we have discussed at length. But what if their answer is "we were able to get volume pricing on that tire and thought our customer's would appreciate the increased reliability of a tire that was not running at maximum capacity". Then I would say go for the XPS Rib if you want to spend that kind of money. What say you?
Now when someone comes along with an axle greater than 6K and wants to put on an XPS Rib (even if they say I scaled my trailer at its maximum load and it weighed 13000 pounds with 2000 pounds of that on the pin), I'm with you on that one -- that is not something that should be done.
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