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-   -   Airstream 25RB with 1300 Pounds of Payload on TV? (http://www.airforums.com/forums/f238/airstream-25rb-with-1300-pounds-of-payload-on-tv-195361.html)

out of sight 05-17-2019 05:32 PM

Quote:

Originally Posted by smithcreek (Post 2242422)
Weird... In the past month you've become an expert on towing with BWM's also?



And that's the advice you gave with absolutely no idea that the hitch in question was some oddball Euro-hitch, completely inadequate for towing a 22' AS. Luckily in that thread there was a person or two with actual BMW towing experience to give good advice and recommend an aftermarket hitch with WD capability.

Yup. You can tow a 22 on the ball with a BMW. I've towed one on the ball with my Mercedes, a similar vehicle. Drives like a charm. No sway either. I'm not sure what BMW says about wd hitches. MB doesn't allow them. Probably BMW doesn't either.

jcl 05-17-2019 05:44 PM

Quote:

Originally Posted by out of sight (Post 2242406)
You are forgetting the fact that there is a 1000 pound engine sitting on the front wheels. If somehow the manufacturer could achieve a 50/50 weight distribution in a front engine vehicle without disturbing the vehicle layout he would surely do it. In order to balance the vehicle for optimal handling and braking you need at east half of the total weight over the rear wheels. It would not be wise to use a weight distribution hitch to put load from the rear axle over to the front axle when there is already too much load there.

You are incorrect when you refer to an unloaded pickup truck as having an overloaded front axle. It simply isn't true. Perhaps what you are trying to say is that the unloaded vehicle has a front axle weight bias, eg there is more weight on the front than the rear. That is even more true when the pickup is equipped with an overweight engine.

The real issue is that such a vehicle can be a danger when driven unladen. That is one reason why owners typically add canopies, tonneau covers, and carry ballast in the box. Of course, doing so means that the assumptions about not requiring a WD hitch are no longer valid.

jcl 05-17-2019 05:51 PM

Quote:

Originally Posted by out of sight (Post 2242451)
I'm not sure what BMW says about wd hitches. MB doesn't allow them. Probably BMW doesn't either.

My BMW X5 had a spec for both WD and non WD towing. Seemed pretty clear to me. Newer BMWs have a dealer-installed hitch option with a quick release ball that isn't suitable for WD equipment. BMW take no position on an owner adding an aftermarket hitch that is suitable for WD equipment. They can't warrant it, as they don't supply it. They refer to axle weight ratings as an upper limit, very logically IMO.

It has also been pointed out to you repeatedly that MB does not have a position banning the use of WD equipment. We went over the Mercedes owner's manual instructions for your specific vehicle in a recent post, where you admitted your error. And here you are back claiming it again.

Repeating falsehoods doesn't make them true.

out of sight 05-17-2019 05:59 PM

Quote:

Originally Posted by jcl (Post 2242456)
My BMW X5 had a spec for both WD and non WD towing. Seemed pretty clear to me. Newer BMWs have a dealer-installed hitch option with a quick release ball that isn't suitable for WD equipment. BMW take no position on an owner adding an aftermarket hitch that is suitable for WD equipment. They can't warrant it, as they don't supply it. They refer to axle weight ratings as an upper limit, very logically IMO.

It has also been pointed out to you repeatedly that MB does not have a position banning the use of WD equipment. We went over the Mercedes owner's manual instructions for your specific vehicle in a recent post, where you admitted your error. And here you are back claiming it again.

Repeating falsehoods doesn't make them true.

If you look at the MB manual and the hitch receiver spec you will see that you can't use a wd hitch. Of course lots of people do, at their own risk of course.

out of sight 05-17-2019 06:06 PM

Quote:

Originally Posted by jcl (Post 2242454)
You are incorrect when you refer to an unloaded pickup truck as having an overloaded front axle. It simply isn't true. Perhaps what you are trying to say is that the unloaded vehicle has a front axle weight bias, eg there is more weight on the front than the rear. That is even more true when the pickup is equipped with an overweight engine.

The real issue is that such a vehicle can be a danger when driven unladen. That is one reason why owners typically add canopies, tonneau covers, and carry ballast in the box. Of course, doing so means that the assumptions about not requiring a WD hitch are no longer valid.

I wouldn't say they are dangerous, just less than ideal. As for towing a trailer with a 900 lb tongue weight a RAM diesel is perfect without a wd hitch. Transferring weight back to the front would be a big mistake. Do the math. RAM publishes the axle base weights so it's pretty easy to figure it out.

jcl 05-18-2019 01:20 AM

Quote:

Originally Posted by out of sight (Post 2242459)
If you look at the MB manual and the hitch receiver spec you will see that you can't use a wd hitch. Of course lots of people do, at their own risk of course.

No, the manual doesn't say that.

It doesn't say anything about WD hitches, as you already agreed. Check the history.

Quote:

Originally Posted by out of sight (Post 2224142)
By the way, the manufacturer of my SUV does not allow weight distribution hitches.

Quote:

Originally Posted by jcl (Post 2224217)
Does not allow, or does not comment on? I reviewed the 2014 ML owner's manual (US version) and it does not mention weight distributing hitches anywhere.

Quote:

Originally Posted by out of sight (Post 2224222)
That's correct. They don't address w/d hitches. So the owner has to take the responsibility. They do limit the hitch pin to ball distances to 7.5" which effectively says you can't use a w/d hitch.

Instead of blindly following the words in the manual, it is more effective to understand what they are saying, and why. They say that the ball must be no more than a certain distance from the pin, for a weight carrying hitch, which is the only design they consider or discuss. We agreed above that they don't consider WD hitches. The maximum distance limitation doesn't apply to WD hitches, due to basic physics. The reasons for a maximum hitch ball distance are that a larger lever arm with a weight carrying hitch applies a larger bending moment to the receiver, and that it multiplies the weight on the tow vehicle rear axle, which is what they are worried about. WD equipment when set up properly reduces the weight on the rear axle. You are simply making it up when you say that the manual says you can't use a WD hitch. You appear to have already formed your own conclusion, and are then trying to twist the manufacturer's words to fit your theory.

Also, you need to understand that you always tow at your own risk. If you think that a manufacturer's spec is a defence after you crash, you should try telling the judge that it couldn't possibly be your fault, since you were within manufacturer's recommendations, and see how far you get.

jcl 05-18-2019 01:28 AM

Quote:

Originally Posted by out of sight (Post 2242460)
I wouldn't say they are dangerous, just less than ideal. As for towing a trailer with a 900 lb tongue weight a RAM diesel is perfect without a wd hitch. Transferring weight back to the front would be a big mistake. Do the math. RAM publishes the axle base weights so it's pretty easy to figure it out.

You failed to address the first part of the quoted post. Be honest now.

As to the second part, we can't do the math and figure it out, since there are no scale tickets indicating the ready-to-camp load in the pickup. You have suggested working off manufacturer's published axle weights, but that ignores everything carried in the box of the pickup. It is illogical.

It is possible that one would tow with a HD pickup with nothing at all in the box, and only the tongue weight, but that begs the question as to why use a HD pickup when there is no plan to carry any cargo? Unless one is simply trying to defend the indefensible?

out of sight 05-18-2019 06:09 AM

Quote:

Originally Posted by jcl (Post 2242510)
You failed to address the first part of the quoted post. Be honest now.

As to the second part, we can't do the math and figure it out, since there are no scale tickets indicating the ready-to-camp load in the pickup. You have suggested working off manufacturer's published axle weights, but that ignores everything carried in the box of the pickup. It is illogical.

It is possible that one would tow with a HD pickup with nothing at all in the box, and only the tongue weight, but that begs the question as to why use a HD pickup when there is no plan to carry any cargo? Unless one is simply trying to defend the indefensible?

The reason that the manufacturer limits the pin to ball distance is that they want to limit the bending moment on the hitch. A wd hitch imparts quite a large bending moment.

You can do the math. Make some reasonable assumptions. The result will be the same, i.e., that it would be foolish to use a wd hitch for this vehicle.

jcl 05-18-2019 10:21 AM

Quote:

Originally Posted by out of sight (Post 2242535)
The reason that the manufacturer limits the pin to ball distance is that they want to limit the bending moment on the hitch. A wd hitch imparts quite a large bending moment.

You can do the math. Make some reasonable assumptions. The result will be the same, i.e., that it would be foolish to use a wd hitch for this vehicle.

Possible, but not certain. If you believe that is the only reason, then show us the manufacturer’s maximum bending moment spec. It isn’t in the manual.

On the other hand, a longer pin to ball distance increases the load on the rear axle. And the manufacturer goes to great length to quote the maximum rear axle load. Ignoring this makes your argument fallacious.

You are taking the lack of a discussion in your manual as proof of a ban. Following that logic, the fact that your owners manual doesn’t mention towing an Airstream means that it isn’t allowed.

The math isn’t hard. But first you have to do the physics. And a course in basic logic wouldn’t hurt either.

Greg1960 05-18-2019 04:48 PM

No worries
 
I have a 2016 Ram 1500 with 3.92 diff and 5.7 Hemi. Payload is 1400lbs or so per sticker. I have towed a 2017 25FB and a 2018 28’ RB from Maine to Florida and back country many times with an Equilizer hitch with no issues, incidents or worries except “road alligators” 😬. I keep the truck fairly empty except for a couple of mountain bikes in the bed.

Enjoy your trailer and have fun!

gypsydad 05-18-2019 05:16 PM

Quote:

Originally Posted by jcl (Post 2242615)
Possible, but not certain. If you believe that is the only reason, then show us the manufacturer’s maximum bending moment spec. It isn’t in the manual.

On the other hand, a longer pin to ball distance increases the load on the rear axle. And the manufacturer goes to great length to quote the maximum rear axle load. Ignoring this makes your argument fallacious.

You are taking the lack of a discussion in your manual as proof of a ban. Following that logic, the fact that your owners manual doesn’t mention towing an Airstream means that it isn’t allowed.

The math isn’t hard. But first you have to do the physics. And a course in basic logic wouldn’t hurt either.

The more I follow this person, the more I am convinced he is a "troll"! :mad: Unfortunate to see this, but it happens from time to time...For me, time to move along to honest folks with real experience and AS knowledge to share...:wally:

jcl 05-18-2019 06:28 PM

Quote:

Originally Posted by gypsydad (Post 2242693)
The more I follow this person, the more I am convinced he is a "troll"! :mad: Unfortunate to see this, but it happens from time to time...For me, time to move along to honest folks with real experience and AS knowledge to share...:wally:

I understand your point, but consider that when he adds his absurd recommendations and claims to a new thread, as he does frequently, he leaves a trail that an unsuspecting newcomer may actually heed, not knowing that the recommendations are not well founded. It doesn’t require endless debate, but pointing out nonsense claims actually serves a purpose for future readers. It flags the questionable poster as exactly that.

thewarden 05-19-2019 12:17 AM

Quote:

Originally Posted by jcl (Post 2242710)
I understand your point, but consider that when he adds his absurd recommendations and claims to a new thread, as he does frequently, he leaves a trail that an unsuspecting newcomer may actually heed, not knowing that the recommendations are not well founded. It doesn’t require endless debate, but pointing out nonsense claims actually serves a purpose for future readers. It flags the questionable poster as exactly that.

Add me to the troll list. I agree wholeheartedly.

SteveSueMac 05-19-2019 04:42 AM

Quote:

Originally Posted by gypsydad (Post 2242693)
The more I follow this person, the more I am convinced he is a "troll"! :mad: Unfortunate to see this, but it happens from time to time...For me, time to move along to honest folks with real experience and AS knowledge to share...:wally:



You can “unfollow” or ignore any individual whose posts you don’t want to see. Ironically, that keeps them out of sight for your experience in the forums.

gypsydad 05-19-2019 08:19 AM

Quote:

Originally Posted by SteveSueMac (Post 2242798)
You can “unfollow” or ignore any individual whose posts you don’t want to see. Ironically, that keeps them out of sight for your experience in the forums.

I'd reply, but I didn't see this anymore!:lol:

HClews 05-19-2019 10:43 AM

Quote:

Originally Posted by gypsydad (Post 2242350)
Nice looking rig; remember, towing isn't the problem for a vehicle; pretty much any vehicle can tow a trailer...it's controlling a heavy TT like an AS, at highway speeds that's more important to consider...also payload....what is the payload of your SUV? What is the tongue weight of your AS? Add that to the total passenger weight and any cargo you carry...are you within the max payload on your driver door sticker??:cool: If so, things are looking good...:flowers:

The posted GVWR of our 2017 Durango is 7,100 lbs. Curb weight is is 5,133, leaving us a payload 1,967 lb. Tow capacity is 7,400 lbs, max hitch weight is 740 lbs.
Our Airstream 27FB has a "base weight" of 5,868 lb, I figure about 6,250 lb as we load it - we strive to keep it light. Tongue weight is 790 lb, but we use a weight-distributing hitch so this cuts it down about 50%. Assuming the tongue load adds 400 lbs to our TV weight, this leaves us about 1,500 lbs useful load.
So although I realize we are pushing the limits, I believe we are still (just barely) OK. As an engineer I understand that the manufacturer's ratings have a built-in safety factor. However, in case of any type of legal action or law suite, the rating numbers would be considered absolute. So to me, this is probably the more important consideration!
Our goal is to have fun - within legal limits. :wally:

SteveSueMac 05-19-2019 02:15 PM

Quote:

Originally Posted by gypsydad (Post 2242828)
I'd reply, but I didn't see this anymore!:lol:



Can anyone tell me if gypsydad responded to my post? 🤪

SteveSueMac 05-19-2019 02:23 PM

Quote:

Originally Posted by HClews (Post 2242863)
The posted GVWR of our 2017 Durango is 7,100 lbs. Curb weight is is 5,133, leaving us a payload 1,967 lb. Tow capacity is 7,400 lbs, max hitch weight is 740 lbs.

Our Airstream 27FB has a "base weight" of 5,868 lb, I figure about 6,250 lb as we load it - we strive to keep it light. Tongue weight is 790 lb, but we use a weight-distributing hitch so this cuts it down about 50%. Assuming the tongue load adds 400 lbs to our TV weight, this leaves us about 1,500 lbs useful load.

So although I realize we are pushing the limits, I believe we are still (just barely) OK. As an engineer I understand that the manufacturer's ratings have a built-in safety factor. However, in case of any type of legal action or law suite, the rating numbers would be considered absolute. So to me, this is probably the more important consideration!

Our goal is to have fun - within legal limits. :wally:



There’s always stories about law suits for over indexing on weights but I’ve never heard a single confirmed case of that. If there is,someone should show it.

Having said that - you say you’re an engineer and get safety margins and manufacturer constraints. So I would suggest the 3-pass method on the CAT scales to know for sure. For example, my 27FB Flying Cloud sees from 5700-6000# when fully loaded for camping with WD applied (so some of the tongue weight is going to those trailer axles). And the tongue is 980# / even though the printed material says it is much lower (833 I believe). I have a heavy hitch that sits on the a-frame so I’m sure that has something to do with it - but the reality is, I just wouldn’t know my weights without those scale trips.

Some will also tell you that because the myriad of measures will conflict - so long as you’re not taxing axles, you may be ok - others will say, pick the strictest constraint and don’t exceed that (e.g., my truck receiver can handle 1500# but AS doesn’t want the tongue to exceed 1000# according to the manual - so while I could jam 1500# on the truck, I keep it to 1000#....).

As an engineer, you’re probably in a better position to decide what works best for you - the scale tickets will just give you great data to work with.

Good luck and happy camping!

gypsydad 05-19-2019 05:00 PM

1 Attachment(s)
Quote:

Originally Posted by HClews (Post 2242863)
The posted GVWR of our 2017 Durango is 7,100 lbs. Curb weight is is 5,133, leaving us a payload 1,967 lb. Tow capacity is 7,400 lbs, max hitch weight is 740 lbs.
Our Airstream 27FB has a "base weight" of 5,868 lb, I figure about 6,250 lb as we load it - we strive to keep it light. Tongue weight is 790 lb, but we use a weight-distributing hitch so this cuts it down about 50%. Assuming the tongue load adds 400 lbs to our TV weight, this leaves us about 1,500 lbs useful load.
So although I realize we are pushing the limits, I believe we are still (just barely) OK. As an engineer I understand that the manufacturer's ratings have a built-in safety factor. However, in case of any type of legal action or law suite, the rating numbers would be considered absolute. So to me, this is probably the more important consideration!
Our goal is to have fun - within legal limits. :wally:

Not to push the question the wrong direction here, but what does the sticker on your drivers door say for "max payload"; (not what you get when you start doing the math for GVWR, etc.) Reason for the question is I would be impressed at a Durango if the payload sticker is even close to the 1,967lbs looks like you have from calculations... The sticker payload number is the important number you don't want to exceed, and of course, get your scale weights as was suggested. If you have 1,967lbs on your payload sticker, that is quite a bit more then most all the RAM 1/2T's have and is impressive! I am sure anyone looking for an SUV would be attracted to a vehicle with that high payload.:cool:

gypsydad 05-19-2019 05:02 PM

Quote:

Originally Posted by SteveSueMac (Post 2242932)
Can anyone tell me if gypsydad responded to my post? ��

All right, I'm back...just couldn't resist...and besides, your posts do make sence...it's the other guy's posts/arguments that were driving me crazy...;)


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