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Old 11-01-2020, 11:54 AM   #241
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Originally Posted by mkcurtiss View Post
Well you know there is a skunk in the woodpile, when Ford states that an F-150 can safely tow 13,500 lbs.....Its just an example.

I often use one of my own vehicles to illustrate the foolishness associated with "tow ratings"......

I have one of those Jeep Cherokee's from back in the day.....its a 1992...terrific vehicle and great fun to own.....most useful vehicle I have ever had.....however....the tow rating on that Jeep is 5000lbs.....Now it has the venerable 4.0 high output straight 6, a wicked strong transmission, and 3:55 rear end....but the thing weighs about 3100 lbs.....
My Airstream weighs about 5000 lbs.....Now I use the Jeep to move the Airstream around my property, albeit in low range 4wd, but it would take an absolutely idiotic buffoon to think it would be safe to tow that Airstream with that Jeep, even though you would be within the "tow capacity"......
The moral of the story is, common sense is the most important element in establishing the suitability of a proper tow vehicle for any trailer or load.
The more I became familiar with the numbers the more I realized that the “tow capacity” numbers are very misleading. Case in point: my previous Tundra (a great 1/2 ton truck) had a tow capacity of 9800 lbs. we know that, for stability, the hitch weight of the trailer should be 10-15% of trailer weight, 980 - 1470 lbs in this case. Even if you move 1/3 of that weight with WD, you still have 650 - 970 lbs of hitch weight on a truck with 1300 lbs payload capacity. IMO keeping the hitch weight at 10% (marginal) is a fools game and not many Airstreams have such a light hitch weight. Not much left over for people and gear.

Going by the GVWR, GAWR ratings is a better method in my opinion.
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Old 11-01-2020, 12:17 PM   #242
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..don’t get me started about the toilets.
They swirl backwards....Do the clocks also run bss ackwards?

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Old 11-01-2020, 01:52 PM   #243
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Originally Posted by Collyn View Post
I agree with the above except only that a typical owner has no safe way of assessing his or her rig's margin of safety. I have (elsewhere) set out a free downloadable multiple question format that enables an owner to realistically assess this - but I fear that forum rules preclude my indicating where.

Collyn
True. I rely on the numbers specified by the manufacturers as my initial cut at mitigating risk. I have confidence in those numbers and I have few other facts to go by anyway. The wide range of opinions on this forum have also helped me make my decisions, but that is a lot more subjective. I would be interested in seeing your list of questions. Can you PM me a link or is that also out of bounds? Thanks.
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Old 11-01-2020, 07:13 PM   #244
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Originally Posted by mpsgolf View Post
I’ve heard the tires spin the opposite direction down under.
That's why we all tow in reverse!

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Old 11-02-2020, 05:46 PM   #245
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This near exact scenario is reported regularly on RV forums across the web. When someone reports a bad handling combination there’s always someone with the same truck same trailer and hitch combination that tows perfectly fine. It’s a trailer loading issue in most cases which seems to always go ignored. You can have 2 trailers loaded to the same overall weight with the same tongue weight % yet one trailer can still have a 30% + higher yaw inertia. That much increase in yaw inertia would result in a 13-15 mph decrease in critical speed and most likely a pitching (porpoising) problem as well which just makes things worse. The given advice is usually to replace the WDH to brand X, upgrade the TV suspension (shocks, air bags), add more tension to the WDH, or replace the TV to the next higher class.
I suppose if you are loading an Airstream with bricks you may be able to get 30% more inertial moment for the same tongue weight. Regular camping gear, not so much. It's why I question the hypothetical 15 mph difference. I agree proper loading (and tire pressure) are very important, and I am sure you will see this kind of thing with utility trailers, but unless you are loading up the hallway in an Airstream, I just don't see this as realistic.

In anycase, if this situation actually came up here, I would know what to advise.
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Old 11-02-2020, 06:01 PM   #246
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Originally Posted by KK4YZ View Post
The more I became familiar with the numbers the more I realized that the “tow capacity” numbers are very misleading. Case in point: my previous Tundra (a great 1/2 ton truck) had a tow capacity of 9800 lbs. we know that, for stability, the hitch weight of the trailer should be 10-15% of trailer weight, 980 - 1470 lbs in this case. Even if you move 1/3 of that weight with WD, you still have 650 - 970 lbs of hitch weight on a truck with 1300 lbs payload capacity. IMO keeping the hitch weight at 10% (marginal) is a fools game and not many Airstreams have such a light hitch weight. Not much left over for people and gear.

Going by the GVWR, GAWR ratings is a better method in my opinion.
The tow numbers are not so misleading as they are misunderstood and misinterpreted. The good folks at Toyota intend for their vehicle to tow all types of trailers. At max limit the trailer type they have in mind is something with most of its weight near the axles so 5-10% tongue weight works. That Tundra is not capable of safely towing a 9,800 lb Airstream. So Toyota is correct about the limit and you also are correct it doesn't work for travel trailers.
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Old 11-02-2020, 06:51 PM   #247
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Originally Posted by BayouBiker View Post
The tow numbers are not so misleading as they are misunderstood and misinterpreted. The good folks at Toyota intend for their vehicle to tow all types of trailers. At max limit the trailer type they have in mind is something with most of its weight near the axles so 5-10% tongue weight works. That Tundra is not capable of safely towing a 9,800 lb Airstream. So Toyota is correct about the limit and you also are correct it doesn't work for travel trailers.
All posts still appear to misunderstand that 'towing capacity' is basically what the vehicle can pull uphill on the end of a rope - not via an overhung hitch.

Collyn
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Old 11-02-2020, 07:03 PM   #248
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Collyn don't forget they do test them for oversteer (.3 g or .4 g depending) and sway (at 62 mph) also. It may not be much, but it's something.
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Old 11-02-2020, 08:40 PM   #249
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IMHO, talk to people with REAL life experience like

some dealers , like canam , have experience they they share
Some do 10-100x time pulling and towing than most of us

i would trust them more than a label stuck on a vehicle
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Old 11-02-2020, 10:48 PM   #250
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Originally Posted by BayouBiker View Post
Collyn don't forget they do test them for oversteer (.3 g or .4 g depending) and sway (at 62 mph) also. It may not be much, but it's something.
Certainly, the SAE J2807 calls for that, but such performance assumes virtually optimal loading, tow ball mass and an optimised tow vehicle. Judging by much on this forum, not too many seem to meet that. Or does this forum attract mainly those with towing issues?

Good luck re the USA elections - most Australians are following it closely. Ours is currently 'Liberal' - which a bit like the USA Democrats - but more left-wing).

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Old 11-02-2020, 10:52 PM   #251
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Originally Posted by waninae39 View Post
IMHO, talk to people with REAL life experience like

some dealers , like canam , have experience they they share
Some do 10-100x time pulling and towing than most of us

i would trust them more than a label stuck on a vehicle
I would canam - but if a dealer tells me the time, my first reaction is to look at my watch. If Oz is anything to go by many were selling real estate - or secondhand cars.

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Old 11-03-2020, 03:38 AM   #252
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I suppose if you are loading an Airstream with bricks you may be able to get 30% more inertial moment for the same tongue weight. Regular camping gear, not so much. It's why I question the hypothetical 15 mph difference. I agree proper loading (and tire pressure) are very important, and I am sure you will see this kind of thing with utility trailers, but unless you are loading up the hallway in an Airstream, I just don't see this as realistic.

In anycase, if this situation actually came up here, I would know what to advise.
It very realistic for any brand RV TT even though many airstream trailers have low payload capacity. You have those that mount bikes, generators, fire wood way out on the rear bumper. You are suggesting that resultant forces along a pivoted beam make little difference regardless of their distance from that pivot? How a TT is loaded along its length is critical to its stability but this fact doesn’t get as much consideration as TW% and overall weight but it should. It isn’t difficult to change a RV TT yaw moment of inertia by 30%.
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Old 11-03-2020, 05:51 AM   #253
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There is yet another geometric parameter (dimension) that’s on the tow vehicle that could also drastically change the handling of near identical rigs. The best thing about lengthening this dimension is it will simultaneously improve both sway dampening and understeer gradient which is rare. And while TV rear overhang has a direct affect on it there are other things that are in direct control of the consumer as well. If you combine this and the differences in trailer yaw moment of inertia, it explains substantial stability differences between near identical combinations in GCWR, TV GVW, TW and, trailer GVW. I don’t ever recall seeing anyone mention it on this or any forum but those that believe they are smarter than everyone else should be able to pin point it.
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Old 11-03-2020, 09:51 AM   #254
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There is yet another geometric parameter (dimension) that’s on the tow vehicle that could also drastically change the handling of near identical rigs. The best thing about lengthening this dimension is it will simultaneously improve both sway dampening and understeer gradient which is rare. And while TV rear overhang has a direct affect on it there are other things that are in direct control of the consumer as well. If you combine this and the differences in trailer yaw moment of inertia, it explains substantial stability differences between near identical combinations in GCWR, TV GVW, TW and, trailer GVW. I don’t ever recall seeing anyone mention it on this or any forum but those that believe they are smarter than everyone else should be able to pin point it.
Well, that last line is rather passive aggressive. I wont submit my answer, for fear of "being smarter than everyone else ".
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Old 11-03-2020, 12:56 PM   #255
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So a side question of sorts for the engineering types on here. Are RV and TT designed differently than utility type trailers? I just picked up 4 1/2 tons of recycle road base in my dump trailer and I picked up a skid steer for a friend on an equipment trailer. I have never seen or heard of Weight Distribution or sway control on trailers like these.

I can see that SC may only be for TTs, as they are big sail-like boxes affected by wind. But what about WD? Do utility trailers center there load more on the there axels? They way I got loaded today, there was a hell of a lot of tongue weight!
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Old 11-03-2020, 11:10 PM   #256
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So a side question of sorts for the engineering types on here. Are RV and TT designed differently than utility type trailers? I just picked up 4 1/2 tons of recycle road base in my dump trailer and I picked up a skid steer for a friend on an equipment trailer. I have never seen or heard of Weight Distribution or sway control on trailers like these.

I can see that SC may only be for TTs, as they are big sail-like boxes affected by wind. But what about WD? Do utility trailers center there load more on the there axels? They way I got loaded today, there was a hell of a lot of tongue weight!
Even the shortest of travel trailers are far longer than your dump trailer. It is that length (rather than their weight) that is the problem - and even more so if anything remotely heavy is located near or on their extreme rear.

I have even towed over two tonnes in a 14 ft trailer behind my 750 kg (1650 lbs) 700 cc Haflinger (that's about the size of a single bed!). Such short trailers have no need for WDHs or sway control.

Virtually all of the stability issues being discussed on this form appear to be by people buying too much travel trailer and too little for whatever attempts to pull it. Then seeking gizmos to fix that.

Apart from a Hensely Hitch, I dislike add-ons. Most are like using a truss to support a hernia. Better by far to avoid whatever is causing that hernia!

Collyn (in Australia - avidly watch the US election).
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Old 11-04-2020, 06:21 AM   #257
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Idk, Profxd, as far as I can recall, every practical measure that can be taken has been mentioned. Trailer loading to reduce inertia and maintain tongue weight, carrying fresh water, TV and TT wheels and tires (quality, size) and tire pressure, tow vehicle loading to increase mass and biasing the weight forward as much as possible, hitch receiver length and shank length, ball height and angle, hitch mount stiffness, springs, shocks, alignment, tow vehicle rear sway bars, removing slop and movement, hitch selection, WD tension, WD bar length.

I've seen all of this mentioned, what are we missing?
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Old 11-04-2020, 06:40 AM   #258
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So a side question of sorts for the engineering types on here. Are RV and TT designed differently than utility type trailers? I just picked up 4 1/2 tons of recycle road base in my dump trailer and I picked up a skid steer for a friend on an equipment trailer. I have never seen or heard of Weight Distribution or sway control on trailers like these.

I can see that SC may only be for TTs, as they are big sail-like boxes affected by wind. But what about WD? Do utility trailers center there load more on the there axels? They way I got loaded today, there was a hell of a lot of tongue weight!
To add to Collyn's comments, the owner has tremendous control over how a utility trailer is loaded so the majority of the mass can be placed over the trailer axle(s) with a slight forward bias to get 7-10% tongue weight. The trailer itself does not contribute much to the total mass. With the mass close to the axles, most of the job to get the mass around a corner is done by the trailer axles so the tow vehicle is mostly required to guide the trailer.

With travel trailers, a significant part of the mass is distributed away from the axles. The longer the trailer the more the inertia from that mass has to be managed by the tow vehicle, this is where the problems start, and this is why long trailers with evenly distributed mass becomes an issue as Collyn indicated.

Experienced haulers load the trailers instinctively to achieve a system that is inherently stable for most speeds. If the system is approaching limits, the driver simply drives more slowly, but as Collyn indicated, the trailers are generally short which self limits the problem.

All of this applies well to car haulers, and boats too.
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Old 11-04-2020, 08:54 AM   #259
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Collyn and Brian, thanks for the explanation! Seems kinda obvious now, short trailer with the weight low and over the axels.
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Old 11-04-2020, 09:30 PM   #260
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Idk, Profxd, as far as I can recall, every practical measure that can be taken has been mentioned. Trailer loading to reduce inertia and maintain tongue weight, carrying fresh water, TV and TT wheels and tires (quality, size) and tire pressure, tow vehicle loading to increase mass and biasing the weight forward as much as possible, hitch receiver length and shank length, ball height and angle, hitch mount stiffness, springs, shocks, alignment, tow vehicle rear sway bars, removing slop and movement, hitch selection, WD tension, WD bar length.

I've seen all of this mentioned, what are we missing?
The nut behind the steering wheel!

Collyn
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