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Old 09-14-2015, 07:30 PM   #31
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"We talked with the factory on a visit/tour about the Load Range C tires just being barely adequate. Their response was that the LR C tires were within specification, and to include LR D tires would encourage the customer to overload other components of the trailer."

This is BS. The manufacturer GVWR applies no matter what changes a customer may make to his vehicle. Forest River is simply using this as an excuse to put on cheap marginal no-name Chinese tires.
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Old 09-15-2015, 09:15 AM   #32
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Originally Posted by Gyrogearloose View Post
"We talked with the factory on a visit/tour about the Load Range C tires just being barely adequate. Their response was that the LR C tires were within specification, and to include LR D tires would encourage the customer to overload other components of the trailer."

This is BS. The manufacturer GVWR applies no matter what changes a customer may make to his vehicle. Forest River is simply using this as an excuse to put on cheap marginal no-name Chinese tires.
True, commonly the limiting factor in calculated GVWR IS the tires. Many trailers use the same frame sections, brakes and suspensions as their larger versions. That is probably the case unless you have the biggest model in a series. I had a 25' travel trailer that was very stiff and tough as hell because it had the same underpinnings as the 30 footers in the same model line.
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Old 09-15-2015, 10:01 AM   #33
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I'm not sure how this is FR's fault. You could visually see what tires were on there, and you had the yellow sticker showing max weights. You had everything you needed to do the math before purchase to see if these tires met your own personal idea of adequate.

By the book, they meet the needs of the max load.

Now yes, a pot hole can cause a blow out, but regular road imperfections, transitions, etc do not require that you add an imaginary number on top of the max weights a tire can support. The tires are rated to accommodate reasonable road imperfections at max weight.
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Old 09-15-2015, 10:11 AM   #34
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True, commonly the limiting factor in calculated GVWR IS the tires. Many trailers use the same frame sections, brakes and suspensions as their larger versions. That is probably the case unless you have the biggest model in a series. I had a 25' travel trailer that was very stiff and tough as hell because it had the same underpinnings as the 30 footers in the same model line.
Mine is a Rockwood 2604WS...one of the smallest ones in the ultra lite series.

My GVWR is 7655 lbs and I'm riding on four 205/75R14 LRC tires that each have a single load rating of 1760 lbs. Total tire load rating is 7040 lbs. This just barely works if the tongue weight is subtracted off the GVWR.


Same with my axles. Each is rated for 3500lbs, so total axle load capacity is 7000 lbs on a trailer that is allowed to weigh 7655 lbs.

Neither tires nor axles seem to allow much margin for axle load variations, side to side weight distribution, front to back weight distribution, tire inflation differences, and so on. A lot of small differences can add up even when the owner makes a good effort to properly load the trailer.
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Old 09-15-2015, 10:33 AM   #35
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Mine is a Rockwood 2604WS...one of the smallest ones in the ultra lite series.

My GVWR is 7655 lbs and I'm riding on four 205/75R14 LRC tires that each have a single load rating of 1760 lbs. Total tire load rating is 7040 lbs. This just barely works if the tongue weight is subtracted off the GVWR.


Same with my axles. Each is rated for 3500lbs, so total axle load capacity is 7000 lbs on a trailer that is allowed to weigh 7655 lbs.

Neither tires nor axles seem to allow much margin for axle load variations, side to side weight distribution, front to back weight distribution, tire inflation differences, and so on. A lot of small differences can add up even when the owner makes a good effort to properly load the trailer.
Crazy incompetent engineering! My 25 footer was a Crossroads. Maybe they look at what axles they have in inventory or what's on special from the supplier. Under build and over build according to the cost, not the need. This is the stuff buyers need to research early on, as ridiculous as it seems to have to do that.
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Old 09-15-2015, 10:36 AM   #36
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Most people switch tires first. Ever heard the words "china bomb". The tires they come with are just adequate (barely)for load rating (by design). Running at their max and having a blow out is normal (search the forum), I have heard people having good luck (recently) with FR giving you money for better tires if you prove you have a blow out (pics and email). I would try that but I would go in not expecting a lot because this is a known TT problem and one of the first upgrades people do.

You are partly correct in your first post, the math to add the the max weight and then minus the TW to see that they are at the max. Having a load on them (by bouncing down/speedbumps) does not change that max, yes you are technically correct the downforce changes the dynamic but it does not change the stated published maxes.

if they failed due to material and not overweight/ road damage or whatever then I would definitely encourage an NT complaint.
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Old 09-15-2015, 10:36 AM   #37
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Originally Posted by Loraura View Post
I'm not sure how this is FR's fault. You could visually see what tires were on there, and you had the yellow sticker showing max weights. You had everything you needed to do the math before purchase to see if these tires met your own personal idea of adequate.

By the book, they meet the needs of the max load.

Now yes, a pot hole can cause a blow out, but regular road imperfections, transitions, etc do not require that you add an imaginary number on top of the max weights a tire can support. The tires are rated to accommodate reasonable road imperfections at max weight.
There is nothing imaginary about the variations between axles. I spoke to a Dexter engineer about this. Two axles side by side, with the same vertical deflection, will load the tires differently just because of manufacturing differences between the axles. The Torflex axles rely on the rubber for the spring, so it's not like a really well controlled spring constant. He figured at least 10% variation. So if you take the total axle rating and divide by the number of wheels to get tire rating, you're likely to end up with one or more overloaded tires. There is a margin built in to the lower rating for dual wheels; the same kind of margin needs to be built in to tandem axles.

There's a document from Carlisle Tire that recommends a 20% tire load margin for exactly this reason.
http://www.carlisletransportationpro..._Practices.pdf

(uggggh...I can't figure out how to get the whole link to post)

My issue with FR is primarily with no-name Chinese junk tires on my trailer. I had a blowout with no obvious cause. I've got 48 years of driving experience and have never had a blowout without cause until this tire on this trailer. I don't intend to let this happen again....
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Old 09-15-2015, 10:50 AM   #38
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Most people switch tires first. Ever heard the words "china bomb". The tires they come with are just adequate (barely)for load rating (by design). Running at their max and having a blow out is normal (search the forum), I have heard people having good luck (recently) with FR giving you money for better tires if you prove you have a blow out (pics and email). I would try that but I would go in not expecting a lot because this is a known TT problem and one of the first upgrades people do.

You are partly correct in your first post, the math to add the the max weight and then minus the TW to see that they are at the max. Having a load on them (by bouncing down/speedbumps) does not change that max, yes you are technically correct the downforce changes the dynamic but it does not change the stated published maxes.

if they failed due to material and not overweight/ road damage or whatever then I would definitely encourage an NT complaint.
I filed a complaint with the NHTSB. When I did this, I noticed a rash of similar complaints a few years ago about a different no name Chinese tire on FR products. The common scenario was a failure without cause within the first couple thousand miles of usage.

My point about the GVWR is that it's set inappropriately high on my trailer. It ought to be set lower to allow some margin, just as dual tires are set 12% lower to allow margin for variation between load bearing of side by side tires.
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Old 09-15-2015, 11:01 AM   #39
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Originally Posted by Gyrogearloose View Post
I filed a complaint with the NHTSB. When I did this, I noticed a rash of similar complaints a few years ago about a different no name Chinese tire on FR products. The common scenario was a failure without cause within the first couple thousand miles of usage.

My point about the GVWR is that it's set inappropriately high on my trailer. It ought to be set lower to allow some margin, just as dual tires are set 12% lower to allow margin for variation between load bearing of side by side tires.
I understand what you are saying but it is not industry practice (in this case) to figure in margin of error/safety. it is up to the consumer to understand the ratings, weight their rigs, and load accordingly. Im not saying what is right or wrong, merely just how it is. As an example just look back to last week with the guy that bought a sherline gauge and was not so presently surprised by his results......
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Old 09-15-2015, 11:24 AM   #40
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I understand what you are saying but it is not industry practice (in this case) to figure in margin of error/safety. it is up to the consumer to understand the ratings, weight their rigs, and load accordingly. Im not saying what is right or wrong, merely just how it is. As an example just look back to last week with the guy that bought a sherline gauge and was not so presently surprised by his results......
I hear you, but don't accept it.
My opinion is that industry practice needs to change.
I'm an engineer, and as such I'm socially unskilled enough to think that I should be noisy about this.

These guys get it:
www.rvsafety.com
They routinely find big differences between loading of wheels on trailers.
But the equipment they use isn't commonly available, and they point out that truck scales can't be trusted to accurately make individual wheel load measurements. So if the average guy can't easily know that one tire is overloaded, the GVWR ought to have enough margin so that it won't be overloaded at max weight.

Also the guys at Carlisle Tire get it. In their 'good practice' document, they recommend allowing a 20% margin on tire loading. This should be taken into account in the GVWR, IMHO.
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