ExRocketScientist
Laurel, MD
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Tireman9 wrote:Great_Danes wrote:OK... so I read through the majority of posts on this thread and there is definitely a lot of good information here!!
The only thing I am a little unclear about is how the load ratings are calculated between ST and LT tires. I am in the process of researching new tires for my 5er and have found that the Goodyear G614 (LR-G, 14 ply, 3750lb capacity, LT tire) would meet my criteria. One of the shops I spoke to also recommended a Kenda Karrier HD Radial (LR-F, 12ply, 3960lb capacity ST tire).
I am confused as to how a LR-F tire can have a higher max laod capacity than a LR-G tire even if they are ST vs. LT. Obviously the Kenda is about 1/2 the cost of the GY. My trailer axles are rated (according to the placard) at 6840lbs but I know they are 7k axles that the manufacturer reduced the rating on to ensure that the standard LR-E tires (rated at 3420lbs) can be used.
And to top it all off, I found I can upgrade to a 17.5" tire (Hercules H-902 245/75R17.5 135/133L 16 ply) including new steel rims for the same cost as the G614. I am leaning towards the 17.5" option because it seems the tires are more readily available than the G614 (at least around here) and of course because the load rating is total overkill for my trailer at 4805lbs per tire. Also, the replacement cost of the 17.5" tire is about $100 less per tire than the G614, so in 5 years when I need to replace tires, my costs will be less.
Does this logic make sense, or am I going way overboard here when I could safely go with the Kenda tire in terms of load capacity and in turn save a whack of dough? Comments?
Others have and will suggest you consider the 17.5 option. I think you have considered the details as long as you confirmed all the components such as axles, springs, hubs, wheels etc.
RE LT load limits vs ST Load limits.
Ther is no direct simple factor to convert load/inflation tables from ST loads to LT loads. ST tires have higher rating becsuse they have shallower tread depth (cooler running), A lower speed limit 65 vs 75 or higher for LT and ST type are intended for Trailer use only in Highway Service. I know of no state that allows people to travel in trailers while in motion so would interpret this to mean not intended to transport people.
And if you go way back through this thread you will see where we discussed the "K" factor. It is a variable in the equation for computing the load capacity of a tire and is related to the severity of the expected service of the tire. The K factor is different between ST tires and LT tires such that if you had two tires of identical construction, size, and inflation pressure, the one that is designated an ST tire will have a higher load rating than the one designated LT. This is because they think a trailer tire has a cushy life compared to a tire on a truck.
Your conclusions about the 17.5 inch upgrade is the same as many others -- and those that plan on keeping their units long enough to go through at least two more sets of tires have chosen to do it for both the economics of it, the serviceablity out on the road, and the reliability of the products.
ERS
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winkyb
Florida
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wrote:
Your conclusions about the 17.5 inch upgrade is the same as many others -- and those that plan on keeping their units long enough to go through at least two more sets of tires have chosen to do it for both the economics of it, the serviceablity out on the road, and the reliability of the products.
Or they don`t worry as much about knocking a hole in the bottom of your RV as they do about killing you.From a law suit point of view.So they will push the ST closer to the point of failing.
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Chris
Shelter Bay, Wa
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winkyb wrote: wrote:
Your conclusions about the 17.5 inch upgrade is the same as many others -- and those that plan on keeping their units long enough to go through at least two more sets of tires have chosen to do it for both the economics of it, the serviceablity out on the road, and the reliability of the products.
Or they don`t worry as much about knocking a hole in the bottom of your RV as they do about killing you.From a law suit point of view.So they will push the ST closer to the point of failing.
I think a more accurate statement is that ST ratings push these tire beyond the normal failure point of a tire that is so lightly constructed if used aware near that rating. In others words they are a tire just looking for a place or point to fail! This is based on their flimsy design that was never intended for what they became. The lower testing standards allowed this to happen! More stringent testing standard would have saved a lot of grief for a lot of boaters, horsemen, rv user and others.
Chris
My Rig
2001.5 2500 STD CAB AUTO SLT 4x4, CTD 4:10's, Bomb'd to Tow
2005 Cardinal 29WBLX.
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Beach-Rat
Northern Virginia
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ST Weight Ratings..
There is more to it.. I don't know what or how but I do know that there is more..
Reason.. I just put the third set of ST tires on in six years.. OE were "Ds".. last set & the new set are "Es". All of the OE tires and three of the four past set of "Es" failed due to belt seperation (goose eggs) the fourth "E" is in small pieces on I-295 so I don't know why it failed. The last OE was kept as a spare and it seperated while hanging under the trailer as a spare.
And while the tires/wheels are being worked on the trailer is sitting on two 225/75-R15 "C" Marathons (made in the USA Marathons) The "Cs" were replaced due to age at 7 years (1996 build date) and 20k miles. They are now mounted on Toyota pick-up wheels (yes, the offset is wrong, way wrong) and they show no signs of coming apart
So.. why does every ST tire that I touch come apart in 2 1/2 to 3 years at less than 15k and the old 1996 "C" Marathons just hang in there.
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CapriRacer
Somewhere in the US
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Beach-Rat wrote:ST Weight Ratings..
There is more to it.. I don't know what or how but I do know that there is more..
Reason.. I just put the third set of ST tires on in six years.. OE were "Ds".. last set & the new set are "Es". All of the OE tires and three of the four past set of "Es" failed due to belt seperation (goose eggs) the fourth "E" is in small pieces on I-295 so I don't know why it failed. The last OE was kept as a spare and it seperated while hanging under the trailer as a spare.
And while the tires/wheels are being worked on the trailer is sitting on two 225/75-R15 "C" Marathons (made in the USA Marathons) The "Cs" were replaced due to age at 7 years (1996 build date) and 20k miles. They are now mounted on Toyota pick-up wheels (yes, the offset is wrong, way wrong) and they show no signs of coming apart
So.. why does every ST tire that I touch come apart in 2 1/2 to 3 years at less than 15k and the old 1996 "C" Marathons just hang in there.
To try to understand so I can answer your question: When you changed to the Load Range E tires - Did you increase the inflation pressure to 80 psi? If not, then you didn't actually change to Load Range E tires. You changed to "Load Range E tires running at Load Range D conditions" - essentailly running a Load Range D tire.
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CapriRacer
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winkyb
Florida
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Beach-Rat wrote:ST Weight Ratings..
There is more to it.. I don't know what or how but I do know that there is more..
Reason.. I just put the third set of ST tires on in six years.. OE were "Ds".. last set & the new set are "Es". All of the OE tires and three of the four past set of "Es" failed due to belt seperation (goose eggs) the fourth "E" is in small pieces on I-295 so I don't know why it failed. The last OE was kept as a spare and it seperated while hanging under the trailer as a spare.
And while the tires/wheels are being worked on the trailer is sitting on two 225/75-R15 "C" Marathons (made in the USA Marathons) The "Cs" were replaced due to age at 7 years (1996 build date) and 20k miles. They are now mounted on Toyota pick-up wheels (yes, the offset is wrong, way wrong) and they show no signs of coming apart
So.. why does every ST tire that I touch come apart in 2 1/2 to 3 years at less than 15k and the old 1996 "C" Marathons just hang in there.
As you in the 70`s and 80`s I don`t ever remember changing a tire other than wore out on a trailer.And I know of at least two boats I had over ten years that still had the tires that came on the trailer.they were close to bald but still did not come apart.And I know at least one boat was very close to capacity for the tires.
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Beach-Rat
Northern Virginia
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CapriRacer wrote:
To try to understand so I can answer your question: When you changed to the Load Range E tires - Did you increase the inflation pressure to 80 psi? If not, then you didn't actually change to Load Range E tires. You changed to "Load Range E tires running at Load Range D conditions" - essentailly running a Load Range D tire.
The "Es" run at 80psi.. all truck & trailer tires run the max PSI (80 for "E" or 65 for "D")
Like Winky.. I remember towing a single axle Wilderness up and down the East Coast with 35psi in the OE tires.. from tire age of 3yo to 9yo with no issues.. and now my "jack stand" tires are 1996 "C" Marathons that ran 7 years towing and still hold the trailer while the "good" tires are being serviced.
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Tireman9
Akron, OH
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Beach-Rat wrote:CapriRacer wrote:
To try to understand so I can answer your question: When you changed to the Load Range E tires - Did you increase the inflation pressure to 80 psi? If not, then you didn't actually change to Load Range E tires. You changed to "Load Range E tires running at Load Range D conditions" - essentailly running a Load Range D tire.
The "Es" run at 80psi.. all truck & trailer tires run the max PSI (80 for "E" or 65 for "D")
Like Winky.. I remember towing a single axle Wilderness up and down the East Coast with 35psi in the OE tires.. from tire age of 3yo to 9yo with no issues.. and now my "jack stand" tires are 1996 "C" Marathons that ran 7 years towing and still hold the trailer while the "good" tires are being serviced.
Tandem axle trailers load tires much more in lateral than single axle trailers. I have limited data that suggests 24% more even with the same scale weight.
The regulations will never change unless there is enough data and hard facts made available to NHTSA so simply complaining to other RV owners will not accomplish much.
You can learn more if you visit my tire blog RVTireSafety
In my opinion as a QS9000 and ISO/TS 16949 Quality auditor the word "Quality" does not appear to be in the RV industry dictionary.
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Francesca Knowles
Port Hadlock, Washington
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Tireman9 wrote:
RE LT load limits vs ST Load limits.
Ther is no direct simple factor to convert load/inflation tables from ST loads to LT loads. ST tires have higher rating becsuse they have shallower tread depth (cooler running), A lower speed limit 65 vs 75 or higher for LT and ST type are intended for Trailer use only in Highway Service. I know of no state that allows people to travel in trailers while in motion so would interpret this to mean not intended to transport people.
I think this interpretation incorrect, for the following reasons:
1) Many States do in fact allow passenger transportation in travel trailers, fifth wheels, or both.
According to this 2010 towing laws by State article, carrying passengers in travel trailers is allowed in eight States:Arizona, Indiana, Iowa, Kansas, Minnestota, Mississippi, Missouri, and Nebraska. The allowance includes fifth wheel trailers.
Nine other States allow passengers in fifth-wheel type trailers only: Montana, New York, North Dakota, Oregon, Pennsylvania, South Dakota, North Dakota, West Virginia, and Wisconsin.
2)LT vs. ST tire "safety" can't be a factor in safety-related prohibitions, since some States actually prohibit passenger transport in truckcampers, among them the "passengers in trailers O.K." North Dakota.
Prohibitions re. trailer passenger transport in all other States are due to the flimsy construction/flying objects nature of trailers/campers, which aren't designed for the protection of life like ordinary vehicles are. (My personal view is that the same holds true for the "living space" areas of most motorhomes, in which passenger protection ends at the cockpit area.)
3) ST tires are installed only on trailers due to intended-use design differences, one of which is noted above: shallower tread depth for cooler running (and better performance re. rolling resistance). The other critical difference that bars their use on drive vehicles is that they are NOT designed for traction/steering axles. Deeper, more aggressive tread and softer sidewalls are what folks need/want for drive vehicles. Those factors reduce the efficiency of a trailer tire, which only needs to "follow" the tow vehicle.
" Not every mind that wanders is lost. " With apologies to J.R.R. Tolkien
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winkyb
Florida
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Tireman9 wrote:Beach-Rat wrote:CapriRacer wrote:
To try to understand so I can answer your question: When you changed to the Load Range E tires - Did you increase the inflation pressure to 80 psi? If not, then you didn't actually change to Load Range E tires. You changed to "Load Range E tires running at Load Range D conditions" - essentailly running a Load Range D tire.
The "Es" run at 80psi.. all truck & trailer tires run the max PSI (80 for "E" or 65 for "D")
Like Winky.. I remember towing a single axle Wilderness up and down the East Coast with 35psi in the OE tires.. from tire age of 3yo to 9yo with no issues.. and now my "jack stand" tires are 1996 "C" Marathons that ran 7 years towing and still hold the trailer while the "good" tires are being serviced.
Tandem axle trailers load tires much more in lateral than single axle trailers. I have limited data that suggests 24% more even with the same scale weight.
The regulations will never change unless there is enough data and hard facts made available to NHTSA so simply complaining to other RV owners will not accomplish much.
Mine were and are tandem axle trailers.21 to 30 foot boats one being a 30 foot sail boat that was right on top of 10,000 pounds.
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