Anyone towing with Mercedes Benz GLS450

[mikeinca]

Originally Posted by Garfish

Mikeinca - your first AS? We love the 25 twin globie

Hi Garfish - no, we had a 30' Classic before the GT. We were seduced by the Classic's size and features but it turned out to be too much trailer for the kind of camping we wanted to do. We also love our 25 Twin Globetrotter; it's perfect for us. Getting solar and lithium batteries installed next month. Can't wait!

[jcl]

Originally Posted by ROBERT CROSS

Yes....You got it. GAWR's are more important than payload estimates on the door jam.

Bob
����

Fully agree.

But what is interesting about the GAWR on the GL is that Mercedes has two values: the rear GAWR on the door placard, and a higher rear GAWR to be applied only when towing. The extra capacity depends on what your actual door placard says, but CanAm reference 200 kg additional.

Seems like if a component is engineered for autobahn speeds it has pretty large safety factors at typical highway/towing speeds

[bono]

I thought it is actually mentioned in the standard manual.

Originally Posted by jcl

Fully agree.

But what is interesting about the GAWR on the GL is that Mercedes has two values: the rear GAWR on the door placard, and a higher rear GAWR to be applied only when towing. The extra capacity depends on what your actual door placard says, but CanAm reference 200 kg additional.

Seems like if a component is engineered for autobahn speeds it has pretty large safety factors at typical highway/towing speeds

[jcl]

Originally Posted by bono

I thought it is actually mentioned in the standard manual.

The spec for the higher rear GAWR is included in the owners manual. Whether the difference is 200 kg or something similar depends on what the owner’s door placard says the standard GAWR is.

[OohWeeLJ]

Holy moly this post has gotten out of hand. Btw...I am a woman and yes the wife that drives the GLS. ��With that said, our choice to tow with our GLS has a lot to do with our lifestyle. One being that we do a lot of city driving, and therefore a pick up truck is not ideal for either my husband and I. Although, admittedly, I think my husband would love a pick up, but again it isn’t practical for us at the moment. We also have 2 young boys, a 5 and 3 year old (both still in carseats) and given the higher chance of tip over with a large pick up and it’s body on frame, we opted to do most of our travels with the family in the safer unibody the GLS has to offer. But, we’re big rule followers, so we have no intention of towing anything beyond the published ratings, therefore we are sticking with the single axle Airstreams with less than 600 lb hitch weight. We didn’t go to any cat scales for our first time pulling a 16ft Bambi, but the GLS pulled it very well! My husband said he often forgot it was there. The AS only had 1 full propane tank and a full tank of water so with the published hitch weight of less than 400 lbs, we figured the hitch weight was less than 600 lbs for our trip. Our cargo was no more than 300 lbs (we’re car campers pre-covid-so we’re used to bringing less) spread into both our TV and the AS. We also only drove about an hour to our campsite. I will say that for our first time, our trip was a success and our children were comfortable and had a great time.

Our next trip, we’ll be pulling a 20ft Bambi...with a WD hitch, so I think we’ll get on the cat scale for that trip to make sure we’re indeed within our limits.

If we decide to ever get a much bigger AS (>22ft)and the kids are much older, I do think my husband would prefer to be pulling a larger AS with a pick up, but for now our large SUV is doing its job as my everyday car and occasional TV for smaller AS.

Thank you all for the help with the hitch.

(Sorry for the upside down photos-thats how it loaded from my phone!)

[mikeinca]

I think your GLS is a great match for the trailers you have planned to tow with it. Good luck and enjoy!

[BayouBiker]

The banter is all a distraction from the main point though. Garfish, I didn't see anybody suggesting you can't make the 7,300 lb 25' work with a GL 450.


bono and gator.bigfoot are suggesting to others that it is possible to safely tow 30-33 foot trailers with vehicles like theirs. Since they won't provide scale tickets, and one of them when pressed admitted they let someone else worry about axle and weight limits, let's use numbers likely to be encountered by people seeking advice about their intended set-ups.

Case one 2021 30 or 33' Classic either one fully loaded with gear, supplies and water GVWR 10,000 lb. They have an 2018 X5 unladen 4805 lbs as equipped with axle limits of 2820 lb front, 3480 lb rear, they have 2 kids and a dog and full tank of gas. Passengers 600 lb, fuel 180 lb, hitch 200 lb.

They have been told there is no room for cargo in the vehicle so they pull up to the CAT scale with snack, phones and jackets but not much else and without the hitch and weigh in. They get 5610 lb GVW 2,760 font 2,850 lb rear.

They have been told to load the trailer for a max of 10% tongue so they have tongue with the Propride hitch at exactly 1000 lb. But 80 lb of the hitch is on the vehicle so effective tongue is 1080.

They hitch up with no WD and get 2,230 front (590 under) and 4,460 rear (980 over)

They add max WD tension (2150 lb) and get 2,760 front (100% FALR) and 3630 rear (150 over). I Distributed 300 lb to the trailer axle. I used actual dimensions so there is no geometry change possible to add more load to the trailer short of overloading the front axle as well. I could go to 112% FALR but this vehicle is already going to have significant over steer issues and will be unstable at highway speeds.

The best I can do has this camper 150 lb over the rear axle limit and is unstable. This camper will have the leave the dog and kids home.....

[gator.bigfoot]

I can guarantee you there is no oversteer. Rock solid performance. When it was setup, it was setup with everything that I normally tow with, including a full tank of water. The company I used is the best in the country, to whom you also have mentioned that you had no issue. They setup thousands of units and have done so for these vehicles and many like them. My discussion with the owner was that all my weights were still well under the published axel weights. So why would I go and weigh the unit again. It has no point.

The issue is you. You cannot accept that you are wrong. You cannot let it go. You can't provide the math because you have no idea how. An armchair engineer is what you are. Let the experts who setup these vehicles properly handle them. You have no idea yet you're pushing your biases on everyone else.

[Nelson428]

Originally Posted by oohweelj

holy moly this post has gotten out of hand. Btw...i am a woman and yes the wife that drives the gls. ��with that said, our choice to tow with our gls has a lot to do with our lifestyle. One being that we do a lot of city driving, and therefore a pick up truck is not ideal for either my husband and i. Although, admittedly, i think my husband would love a pick up, but again it isn’t practical for us at the moment. We also have 2 young boys, a 5 and 3 year old (both still in carseats) and given the higher chance of tip over with a large pick up and it’s body on frame, we opted to do most of our travels with the family in the safer unibody the gls has to offer. But, we’re big rule followers, so we have no intention of towing anything beyond the published ratings, therefore we are sticking with the single axle airstreams with less than 600 lb hitch weight. We didn’t go to any cat scales for our first time pulling a 16ft bambi, but the gls pulled it very well! My husband said he often forgot it was there. The as only had 1 full propane tank and a full tank of water so with the published hitch weight of less than 400 lbs, we figured the hitch weight was less than 600 lbs for our trip. Our cargo was no more than 300 lbs (we’re car campers pre-covid-so we’re used to bringing less) spread into both our tv and the as. We also only drove about an hour to our campsite. I will say that for our first time, our trip was a success and our children were comfortable and had a great time.

Our next trip, we’ll be pulling a 20ft bambi...with a wd hitch, so i think we’ll get on the cat scale for that trip to make sure we’re indeed within our limits.

If we decide to ever get a much bigger as (>22ft)and the kids are much older, i do think my husband would prefer to be pulling a larger as with a pick up, but for now our large suv is doing its job as my everyday car and occasional tv for smaller as.

Thank you all for the help with the hitch.

(sorry for the upside down photos-thats how it loaded from my phone!)

Attachment 1

[Nelson428]

[BayouBiker]

Originally Posted by gator.bigfoot

I can guarantee you there is no oversteer. Rock solid performance. When it was setup, it was setup with everything that I normally tow with, including a full tank of water. The company I used is the best in the country, to whom you also have mentioned that you had no issue. They setup thousands of units and have done so for these vehicles and many like them. My discussion with the owner was that all my weights were still well under the published axel weights. So why would I go and weigh the unit again. It has no point.

The issue is you. You cannot accept that you are wrong. You cannot let it go. You can't provide the math because you have no idea how. An armchair engineer is what you are. Let the experts who setup these vehicles properly handle them. You have no idea yet you're pushing your biases on everyone else.

Gator the math equations regarding stability include complex matrix operations and include solving the eigenvalues to obtain solutions. It involves 6 order determinates. There are imaginary components with no single solutions and the Laplace transforms are nearly as difficult to obtain. It would be pointless to offer the math here. There are a number of papers online which provide simplified models using fourth order equations and treating the vehicle and trailer as if they are bicycles, but the solution equations still cannot be written out, the best one can do is graph the solutions. The model I have used is written in MatLab (short for Matrix Laboratory).

You cannot assure anyone your system doesn't oversteer on high g cornering at highway speeds without testing it, something that would be very risky to attempt. All you can say is thus far, you have not experienced oversteer. The truth is you don't know your vehicle's understeer gradient nor do you know how the trailer influences it at various speeds.

I did notice you had no comment about the axle limit example shall we next look at a GL 450? Perhaps you might provide the door label limits on yours so we can make it real.

[Tiny Cloud]

Originally Posted by gator.bigfoot

So why would I go and weigh the unit again. It has no point.

The issue is you. You cannot accept that you are wrong. You cannot let it go. You can't provide the math because you have no idea how. An armchair engineer is what you are. Let the experts who setup these vehicles properly handle them. You have no idea yet you're pushing your biases on everyone else.

In my opinion, the math has been provided several times through several posts from several different experienced drivers. Seems to me, you are the armchair engineer.

I weigh on every trip out. I do agree whatever setup you had from the original day was perfect. But loads change on every trip, especially when you add stuff believing it's ok for a few extra pounds.

I occasionally tow with my 2020 GLE450. I know my weights, and I know I don't have much play with payload in the TV. With 600 on the tongue, and two passengers up front, I am lucky if I can carry a 12 roll of confiscated toilet paper. And the 19 footer only has about 200 lbs carrying capacity left too.

It works for you great. You enjoy your ride, but don't be so bold as to say others here are far less superior in knowledge than the company you paid money to solve your problem. Give me some money and I'll solve your problem also, whatever it is. And also get a signature on a liability form just in case.

[ROBERT CROSS]

And actual loaded for camping weights are NOT needed on this thread....


All the talk about door sticker weights is fine, but guessing actual on the road weights is not...SAFE towing requires REAL numbers, rationalize all you want but getting the real numbers and adjusting accordingly is the best road to safe trailering.
Even from the GWN...no loaded for camping numbers.

Disclaimer...I won't post any weight tickets because it seems the true believers say they are meaningless when towing with their TV's.

Bob
🇺🇸

[bono]

No math was provided. Just claims that model shows this or that. The model is useless, I can tell you that for sure. I can feel the difference in handling when changing from all season 18 inch wheels to 20 inch summer inch. Let alone a number of different gactory suspension setups. At the same time our forum mathematician is preaching that this car is OK to tow up to 37 mph and the other will handle 23.5 ft trailer up to 48.7 mph.

Who to believe? My actual experience and expert who are doing this for living or armchair engineer... decisions, decisions...

Originally Posted by Tiny Cloud

In my opinion, the math has been provided several times through several posts from several different experienced drivers. Seems to me, you are the armchair engineer.

I weigh on every trip out. I do agree whatever setup you had from the original day was perfect. But loads change on every trip, especially when you add stuff believing it's ok for a few extra pounds.

I occasionally tow with my 2020 GLE450. I know my weights, and I know I don't have much play with payload in the TV. With 600 on the tongue, and two passengers up front, I am lucky if I can carry a 12 roll of confiscated toilet paper. And the 19 footer only has about 200 lbs carrying capacity left too.

It works for you great. You enjoy your ride, but don't be so bold as to say others here are far less superior in knowledge than the company you paid money to solve your problem. Give me some money and I'll solve your problem also, whatever it is. And also get a signature on a liability form just in case.

[BayouBiker]

Originally Posted by bono

No math was provided. Just claims that model shows this or that. The model is useless, I can tell you that for sure. I can feel the difference in handling when changing from all season 18 inch wheels to 20 inch summer inch. Let alone a number of different gactory suspension setups. At the same time our forum mathematician is preaching that this car is OK to tow up to 37 mph and the other will handle 23.5 ft trailer up to 48.7 mph.

Who to believe? My actual experience and expert who are doing this for living or armchair engineer... decisions, decisions...

I show the 2018 X5 towing the 30' Classic 150 lb over the rear axle limit with a propride hitch and 100% FALR stable to about 61 mph, when I go to 112% FALR, the front axle is 35 lb over limit and the rear axle is 35 lb over the limit. Now the stability speed is 58 mph.

Sorry bono, the X5 is hard pressed to safely tow a 30' airstream and can't stay below its axle weight limits. Sir Newton's Classical Physics will not be cheated.

[jcl]

Originally Posted by BayouBiker

Gator the math equations regarding stability include complex matrix operations and include solving the eigenvalues to obtain solutions. It involves 6 order determinates. There are imaginary components with no single solutions and the Laplace transforms are nearly as difficult to obtain. It would be pointless to offer the math here. There are a number of papers online which provide simplified models using fourth order equations and treating the vehicle and trailer as if they are bicycles, but the solution equations still cannot be written out, the best one can do is graph the solutions. The model I have used is written in MatLab (short for Matrix Laboratory).

TLDR version: it is too complicated for anyone to understand except the poster.

OK. Nobody wants to check your math. It would be interesting to see what you use as variables, and what you simply make assumptions about. For example, many experts discuss tire variables as they relate to combination vehicle stability. You previously commented, when asked, that there is no difference in your model for tire and suspension variables. Some consider those important variables in towing stability. There are models out there developed to do this, using up to 32 degrees of freedom in one paper. How does your model handle various designs of WD hitch? And given the importance of setup, how do you tune your model for all of those different combinations and permutations?

Originally Posted by BayouBiker

You cannot assure anyone your system doesn't oversteer on high g cornering at highway speeds without testing it, something that would be very risky to attempt. All you can say is thus far, you have not experienced oversteer. The truth is you don't know your vehicle's understeer gradient nor do you know how the trailer influences it at various speeds.

You are ignoring that the supplier referenced here, and which you said you had confidence in, tests all their combinations. They have a skid pad. You must have one as well, for tuning your model, no?

Originally Posted by BayouBiker

I did notice you had no comment about the axle limit example shall we next look at a GL 450? Perhaps you might provide the door label limits on yours so we can make it real.

No need. The manual says that irregardless of the door label limit for solo operation, there is a higher GAWR for towing on this model. See the manual. This point has already been discussed.

[BayouBiker]

jcl, I suggested anyone interested in the math can find papers online describing it in detail and it would be futile to try to repeat it here. I fully believe there are millions capable of reading those papers and understanding the math. I explained previously my model are adjusted to available tests of the vehicle. X5 skid pad data is public domain and available. I use stock configurations for that reason and don't use alternate wheels, tires, suspension components or adjustments because I don't have anything to calibrate against. That is not the same as suggesting there is no difference. I have to take a couple simplifying liberties with the model to adjust for WD hitches. For the Hesley and Propride, I had to vary the effective hitch point based on ball angle. There are papers with adjusted matrix formulas that treat it perhaps a bit better, but I was unable to make the modeler work with those. The iterations would not converge, I concluded I made mistakes and gave up on that approach. No way to tune the model for Hesley type, but I did sensitivity analysis and found the differences are less than 5% or 3 mph at 60 mph, which is much better than ignoring the superior performance of the Hensley design and using a simple yaw damping model.

I have no technical beef with CanAm, I have said that many times now. I don't ignore what they do, but I haven't been able to find test results at US highway speeds. I'm pretty sure I know why that is.

I don't much care where the axle load limit is published or obtained. I'd just be happy to have and use it as an example.

[BayouBiker]

Case 2 has us with a 2018 GLS 450 . Same family and same trailer. I can shoehorn them in with 10 lbs to spare front and rear. Of course the setup is well over the GVWR and GCWR. Once again, we are using a very ill advised 10% tongue weight. The Propride Hitch is mandatory to address the inherent sway instability and partially discourage oversteer. I get a stability speed of 67 mph for this configuration. This setup is not for the newbie or the meek either.

[bono]

Just a rhetorical question - who would benefit from these "calculations"? People who believe that only trucks can tow, do not care and do not even consider towing with anything different than a truck. People who know that there are (in many cases better) alternatives, do not care about such calculations and they (we) know that they are inaccurate.

[BayouBiker]

I would think those who are new to camping and want sound unbiased advice. I prefer driving my wife's new European SUV over her big *** truck (you will probably be surprised to learn what I drive) and if we had a smaller trailer and less stuff to cart around, you can bet I'd be singing the praises of her hot little towing marvel.

Edit: It is unwise to scoff at Newton, Einstein, Fourier and Laplace