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Old 10-08-2013, 03:57 AM   #81
Ozz
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Nice post fauch
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Old 10-08-2013, 09:04 AM   #82
Tom S.
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Quote:
quote:Originally posted by Irlpguy

Quote:
quote:Originally posted by Tom S.

For example, truck tires are required to have a 15% safety margin built into them. To my knowledge, there is no such regulation for trailer tires.
I am not going to call this statement "Bogus" but I am going to call it incorrect, and a prime example of misinformation that has been and continues to be spread around this forum and others regarding "safety margin/reserve capacity".

Rather than continue to make this kind of unsubstantiated statement it would be great to be shown something that proves this besides some self professed tire experts interpretation of the following DOT ruling.

The true facts are contained in this document:

http://www.nhtsa.gov/cars/rules/ruli...dex.html#ref74

I refer you to section "D - Tire selection criteria/De-Rating of P metric tires". It may be a little long and difficult to understand for some, but it is the Automobile manufacturers responsibilty to ensure the rating on the tire exceeds the normal load capacity of the vehicle by the established percentage of 94% based on the vehicle manufacturers sticker load/pressure rating. Until this new ruling, the load reserve was based on the rating as stamped on the tire and resulted in an approx 15% reserve.

LT tires and ST tires are not comparable since they are designed for an entirely different purpose, they both are DOT rated and tested and must meet the standards for their application. An LT tire DOT rated for 3042 lbs is rated for exactly that, not 3042 lbs plus 15% reserve capacity or safety margin.

I for the umpteenth time remind everyone I am no tire expert but if I am wrong about this please, please show me the proof.
I'm merely repeating what the rep from Tredit told us at the rally. He said it is the result of the Ford/Firestone fiasco. In his words, it is not an advertised fact (I'm reading between his lines here: because they don't want the public to push the tires to that limit.) but the government told LT tire makers (he said nothing about passenger car tires, probably because we weren't discussing them, nor does Tredit supply them) to manufacture their tires with a 15% safety factor. If you want to correct him, I'll try to find his name and number, or you can come to next year's rally and call him out on it. Given his job, I'm pretty sure he an expert.
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Old 10-08-2013, 10:08 AM   #83
Irlpguy
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Quote:
quote:Originally posted by Tom S.

I'm merely repeating what the rep from Tredit told us at the rally. He said it is the result of the Ford/Firestone fiasco. In his words, it is not an advertised fact (I'm reading between his lines here: because they don't want the public to push the tires to that limit.) but the government told LT tire makers (he said nothing about passenger car tires, probably because we weren't discussing them, nor does Tredit supply them) to manufacture their tires with a 15% safety factor. If you want to correct him, I'll try to find his name and number, or you can come to next year's rally and call him out on it. Given his job, I'm pretty sure he an expert.
Tom since you did not identify your "source", my reference was obviously not directed at anyone at Tredit. The link I provided is an official ruling, where interested parties presented their cases and rules regarding safety/reserve were set. The provision that automobile and LT manufacturers must not rate the capacity of their vehicles on the Max DOT load @ pressure rating of the tire, but must reduce that by what amounts to approximately 15% of the DOT rating. The tire remains rated at it's DOT rating not more and not less. Look at the tire stickers on any car or LT, you will never see the load rating as high as the DOT rating stamped on the tire, the recommended pressure and load will always be reduced. This is what for an LT tire provides the safety factor and load reserve.

There is no such requirement for vehicles using ST tires, if there were, manufacturers would only be able to set the load capacity based on 85% of the DOT rating. Because there is no ruling on anything but automobile and LT's, trailer manufacturers are able to rate their "vehicle" at the full capacity as stated on the tire.

Because Keystone puts Goodyear Marathon ST tires rated at 3402 on Dexter axles rated for 7k each, Keystone must reduce the GAWR on units with 7k axles down to 6750 so that the the least common denominator is taken into account, that being the tire. This is the case with all of the manufactured units using these tires on 7k axles. The law is that if you reduce the capacity of an axle with a tire rated less than the axle, then the VIN sticker must reflect that, it does on mine and any others I have looked at.

How is the mysterious 15% safety margin to be accomplished in an ST tire other than to have the DOT rating reduced by 15% when they are reflecting the load capacity on the VIN sticker.

I have provided a link to official documentation regarding reserve capacity and have asked that if anyone can dispute this or provide any other information that proves an LT tire has a built in reserve capacity to step up to the plate and provide it.

I suggest folks read the information I provided in the link.


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Old 10-08-2013, 10:33 AM   #84
fauch
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Thanks Ozz

I stated in a thread back in 11' that as long as i followed these tire threads and saw the discussion focus erring to the side of emotion that it would be difficult for me to be quiet when i saw a gap between the emotional discussion and SAFETY. Brand bashing has kept us from learning about tire specifications vs load, speed, pressure and life expectancy.
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Old 10-08-2013, 12:37 PM   #85
Tom S.
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Quote:
quote:Originally posted by Irlpguy

Quote:
quote:Originally posted by Tom S.

I'm merely repeating what the rep from Tredit told us at the rally. He said it is the result of the Ford/Firestone fiasco. In his words, it is not an advertised fact (I'm reading between his lines here: because they don't want the public to push the tires to that limit.) but the government told LT tire makers (he said nothing about passenger car tires, probably because we weren't discussing them, nor does Tredit supply them) to manufacture their tires with a 15% safety factor. If you want to correct him, I'll try to find his name and number, or you can come to next year's rally and call him out on it. Given his job, I'm pretty sure he an expert.
Tom since you did not identify your "source", my reference was obviously not directed at anyone at Tredit. The link I provided is an official ruling, where interested parties presented their cases and rules regarding safety/reserve were set. The provision that automobile and LT manufacturers must not rate the capacity of their vehicles on the Max DOT load @ pressure rating of the tire, but must reduce that by what amounts to approximately 15% of the DOT rating. The tire remains rated at it's DOT rating not more and not less. Look at the tire stickers on any car or LT, you will never see the load rating as high as the DOT rating stamped on the tire, the recommended pressure and load will always be reduced. This is what for an LT tire provides the safety factor and load reserve.

There is no such requirement for vehicles using ST tires, if there were, manufacturers would only be able to set the load capacity based on 85% of the DOT rating. Because there is no ruling on anything but automobile and LT's, trailer manufacturers are able to rate their "vehicle" at the full capacity as stated on the tire.

Because Keystone puts Goodyear Marathon ST tires rated at 3402 on Dexter axles rated for 7k each, Keystone must reduce the GAWR on units with 7k axles down to 6750 so that the the least common denominator is taken into account, that being the tire. This is the case with all of the manufactured units using these tires on 7k axles. The law is that if you reduce the capacity of an axle with a tire rated less than the axle, then the VIN sticker must reflect that, it does on mine and any others I have looked at.

How is the mysterious 15% safety margin to be accomplished in an ST tire other than to have the DOT rating reduced by 15% when they are reflecting the load capacity on the VIN sticker.

I have provided a link to official documentation regarding reserve capacity and have asked that if anyone can dispute this or provide any other information that proves an LT tire has a built in reserve capacity to step up to the plate and provide it.

I suggest folks read the information I provided in the link.
I suggest you read it too. From the summary:

(5) Tire Selection Criteria/De-Rating of P-metric Tires - the agency proposed retaining the de-rating percentage of 1.10 for P-metric tires used on non-passenger car vehicles and revising FMVSS No. 110 to specify that the determination of vehicle normal load ("reserve load") on the tire be based on 85% of the load at vehicle placard pressure.

(emphasis added by me). Looks to me like the Tredit rep was right.

But then I'm no tire expert either.
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Old 10-08-2013, 04:48 PM   #86
bncinwv
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I can't resist, it also states in the first section that all of this only applies to vehicles under 10,000 pounds. Last time I checked, that pretty much excludes all of the tires that are on the Montana's except maybe the High Country models?? Unless I read it wrong, and if so, all it will take is a simple correction and once again I will consider myself educated!!
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Old 10-08-2013, 06:12 PM   #87
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quote]Originally posted by Tom S.

I suggest you read it too. From the summary:

(5) Tire Selection Criteria/De-Rating of P-metric Tires - the agency proposed retaining the de-rating percentage of 1.10 for P-metric tires used on non-passenger car vehicles and revising FMVSS No. 110 to specify that the determination of vehicle normal load ("reserve load") on the tire be based on 85% of the load at vehicle placard pressure.

(emphasis added by me). Looks to me like the Tredit rep was right.

But then I'm no tire expert either.
[/quote]

Let me tell you Tom I have read this more than once, and have consulted someone whom I believe to be an expert, not on tires but in interpreting these rules.

You have changed the wording of the first paragraph sufficiently to alter how the actual statement might be interpreted. If you are going to quote something to prove your point then quote it verbatim. According to your post the Tredit fellow said “In his words, it is not an advertised fact (I'm reading between his lines here: because they don't want the public to push the tires to that limit.) but the government told LT tire makers (he said nothing about passenger car tires, probably because we weren't discussing them, nor does Tredit supply them) to manufacture their tires with a 15% safety factor.” I wonder where this “government instruction” is written because it sure is not in this document, which deals with Vehicle Manufacturers.

Nowhere in this document does it refer to “any” directive or rule made to LT Tire manufacturers with respect to building in safety factor.

Here is a short paragraph from the document:
"For the final rule, the agency has also decided to retain the de-rating factor of 1.10 for P-metric tires used on non-passenger car vehicles. For non-passenger car vehicles equipped with P-metric tires, the vehicle normal load shall be not greater than the derated value of 94% of the tire load rating at the vehicle's placard pressure. This de-rating provides a greater load reserve when these tires are installed on vehicles other than passenger cars. For the first time, this final rule requires light trucks to have a specified tire reserve, the same as for passenger cars, under normal loading conditions."

This means to me that now light truck manufacturers must de-rate the load factor of the tires they put on their trucks by the same percentage as car manufacturers are required to do. It does not mean tire manufacturers are required to build in a 15% safety factor into their LT tires.

I cannot see that any proof has been provided to show that the fellow from Tredit was correct, in fact by changing the wording of the paragraph you discredited your case.

Bingo the wording is this: "The vehicle industry commenters supported the extension of FMVSS No. 110 applicability to light trucks, MPVs and vans under 10,000 GVWR." I interpret that to only include “motorized” vehicles, how does an RV fit in that statement?
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Old 10-09-2013, 03:02 AM   #88
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That is what I am wondering Ed, does this apply to large RV's since I thought that is the focus of the thread. In the highlights of the final rule section, it mentions trailers, but I do not know if that specifically relates to fifth-wheels and travel trailers? It does reiterate the weight criteria as:

"The resulting final rule establishes new and more stringent tire performance requirements that apply to all new radial tires for use on passenger cars, multipurpose passenger vehicles, trucks, buses and trailers that have a gross vehicle weight rating (GVWR) of 4,536 kg (10,000 pounds) or less and that are manufactured after 1975, and to all new passenger cars, multipurpose passenger vehicles, trucks, buses and trailers that have a GVWR of 4,536 kg (10,000 pounds) or less."

Underlines added by me for emphasis.

I guess what I gather from all of this is there are a lot of marginal tires out there, which is why I opted for 614's with 7500 pounds of capacity for each 7000 pound axle (at 110 psi). I went to the G-rated tires based on previous bad experiences by myself and other forum members. I was fortunate to have the knowledge beforehand, what is disturbing is that the vast majority of purchasers do not have this knowledge beforehand in order to evaluate options. I did notice that on our new ordered rig, the allowable total weight for the rig has been bumped to 16,000 pounds on the rig placard, but it also specifically mentions G-rated tires at 110 psi as well. I have no clue as to whether or not these other marginal tires could be successfully challenged in court as I am not a lawyer. I would guess the initial step would be to see if there is a lawyer interested in representing such a case.

Bingo
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Old 10-09-2013, 04:28 AM   #89
Tom S.
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Quote:
quote:Originally posted by Irlpguy

quote]Originally posted by Tom S.

I suggest you read it too. From the summary:

(5) Tire Selection Criteria/De-Rating of P-metric Tires - the agency proposed retaining the de-rating percentage of 1.10 for P-metric tires used on non-passenger car vehicles and revising FMVSS No. 110 to specify that the determination of vehicle normal load ("reserve load") on the tire be based on 85% of the load at vehicle placard pressure.

(emphasis added by me). Looks to me like the Tredit rep was right.

But then I'm no tire expert either.
Let me tell you Tom I have read this more than once, and have consulted someone whom I believe to be an expert, not on tires but in interpreting these rules.

You have changed the wording of the first paragraph sufficiently to alter how the actual statement might be interpreted. If you are going to quote something to prove your point then quote it verbatim. According to your post the Tredit fellow said “In his words, it is not an advertised fact (I'm reading between his lines here: because they don't want the public to push the tires to that limit.) but the government told LT tire makers (he said nothing about passenger car tires, probably because we weren't discussing them, nor does Tredit supply them) to manufacture their tires with a 15% safety factor.” I wonder where this “government instruction” is written because it sure is not in this document, which deals with Vehicle Manufacturers.

Nowhere in this document does it refer to “any” directive or rule made to LT Tire manufacturers with respect to building in safety factor.

Here is a short paragraph from the document:
"For the final rule, the agency has also decided to retain the de-rating factor of 1.10 for P-metric tires used on non-passenger car vehicles. For non-passenger car vehicles equipped with P-metric tires, the vehicle normal load shall be not greater than the derated value of 94% of the tire load rating at the vehicle's placard pressure. This de-rating provides a greater load reserve when these tires are installed on vehicles other than passenger cars. For the first time, this final rule requires light trucks to have a specified tire reserve, the same as for passenger cars, under normal loading conditions."

This means to me that now light truck manufacturers must de-rate the load factor of the tires they put on their trucks by the same percentage as car manufacturers are required to do. It does not mean tire manufacturers are required to build in a 15% safety factor into their LT tires.

I cannot see that any proof has been provided to show that the fellow from Tredit was correct, in fact by changing the wording of the paragraph you discredited your case.

Bingo the wording is this: "The vehicle industry commenters supported the extension of FMVSS No. 110 applicability to light trucks, MPVs and vans under 10,000 GVWR." I interpret that to only include “motorized” vehicles, how does an RV fit in that statement?
[/quote]

I changed nothing, other than the underlining. It was a copy and paste. I am done responding here. Go ahead and have the last word.
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Old 10-09-2013, 04:43 AM   #90
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This thread has run its course and is being locked. Thanks to everyone. RVWheels, MOC Admin.
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