Towing 27FB Globetrotter with Mercedes GL450

[thewarden]

Originally Posted by jcl

What an absurd comment.

The Fiat 500 has a payload of 800 lbs, which includes the driver and any passengers. Now think about the 1000 lb tongue weight. You can not tow a 27 foot Airstream with the Fiat 500. It isn't a matter of anxiety, it is a matter of physics.

I agree, this is an absurd comparison. Technically, a GL450 is perfectly capable of towing the 27FB with no problem. And as far as the structural changes that some advocate to the hitch receiver, I am not sure this is necessary at all. The receiver on my Cayenne is rated for much less than the OPs GL, (770lbs compared to 900lbs). What I have gleaned from my research is the weight ratings on these hitch receivers is very subjective. As an example, earlier model Cayennes and VW Touareg receivers were rated at 604lbs while the later models were rated at 770lbs. They are identical in every way, (including the PNs), except for the weight rating sticker. In fact, VW will send you the 770 sticker to replace the other one if you ask.

I have towed my 27 FB with the Cayenne for many thousands of miles with no issues whatsoever and have always been able to stay within all of my weight ratings. I use the shortest shank possible, as advocated by Andy at CanAm, make sure my hitch is properly set up and I inspect the hitch receiver frequently while we travel and it has not moved a mm.

Yes, the GL will be close to it's limits but if you are mindful of what your are loading in the GL and the AS, and stay within load ratings, it will make an excellent tow vehicle for the 27GT

A Fiat on the other hand, cmon, there is absolutely no comparison. Absurd comparison indeed.

[jcl]

Originally Posted by franklyfrank

It was meant to be absurd.
Just as absurd as the idea of towing with a marginal SUV that needs to be modified to do job.
Most serious accidents that I have seen posted involved Airstreams being towed by and SUV.

The SUV doesn't need to be modified. The powertrain, cooling, and suspension are all appropriate for towing this size of trailer.

The standard hitch receiver may need to be modified. Or one could purchase an aftermarket receiver that is rated higher. Just like some owners do with heavy duty pickups, when they replace the marginal factory receivers with Curt, Reese, or other aftermarket receivers that are built to have more capacity. It is a common upgrade to vehicles up through one ton pickups.

Most serious crashes that I know about have involved driver error, whether in setup, or operation. It is a dangerous fallacy to over-rely on equipment selection and think that because one has purchased an overweight tow vehicle, or one rated for very large cargo capacity, that therefore one doesn't need to pay attention to setup and operation.

[thewarden]

Originally Posted by jcl

The SUV doesn't need to be modified. The powertrain, cooling, and suspension are all appropriate for towing this size of trailer.

The standard hitch receiver may need to be modified. Or one could purchase an aftermarket receiver that is rated higher. Just like some owners do with heavy duty pickups, when they replace the marginal factory receivers with Curt, Reese, or other aftermarket receivers that are built to have more capacity. It is a common upgrade to vehicles up through one ton pickups.

Most serious crashes that I know about have involved driver error, whether in setup, or operation. It is a dangerous fallacy to over-rely on equipment selection and think that because one has purchased an overweight tow vehicle, or one rated for very large cargo capacity, that therefore one doesn't need to pay attention to setup and operation.

As the OP has already installed an aftermarket Curt hitch rated much higher than the Mercedes factory hitch, he should be good to go, in my opinion.

I agree, I would fact check the statement "Most serious accidents that I have seen posted involved Airstreams being towed by and SUV."

[panamerican]

Originally Posted by thewarden

What I have gleaned from my research is the weight ratings on these hitch receivers is very subjective. As an example, earlier model Cayennes and VW Touareg receivers were rated at 604lbs while the later models were rated at 770lbs. They are identical in every way, (including the PNs), except for the weight rating sticker. In fact, VW will send you the 770 sticker to replace the other one if you ask.

Yes, the GL will be close to it's limits

as advocated by Andy at CanAm

I'm not sure I agree here. VW owns Porsche and VW hasn't had the most stellar reputation in terms of engineering honesty. I have no idea what went into the "sticker" upgrade, but I can tell you that hitch ratings in the real world are not subjective. You buy a Reese receiver hitch with at 1200lb hitch capacity, it's 1200lbs.

Which brings me back to my point, if it's razor close, why do it? In my book anything worth doing is worth doing well. Tow vehicle and RV selection is no different in my book.

And for the record, Andy is referring him to a place that can do reinforcement.

I think the GL450 is a wonderful vehicle as is Cayenne and would drive them with passion any chance I got, and even tow a boat or 5000-6000lb trailer, but as with most vehicles, they are purpose built. The GL450 is outclassed by the numbers alone. You may drive a million miles safely towing your trailer with the suggested setup, but you may find on that one fateful day, when all the variables are aligned, your trailer will drive you, not the other way around. I've seen it so very many times on the interstate. Tail wagging the dog so to speak.

[panamerican]

Originally Posted by jcl

Most serious crashes that I know about have involved driver error, whether in setup, or operation. It is a dangerous fallacy to over-rely on equipment selection and think that because one has purchased an overweight tow vehicle, or one rated for very large cargo capacity, that therefore one doesn't need to pay attention to setup and operation.

I don't think folks over rely on vehicles that by the numbers that support the size and weights of trailers purchased. I think folks who buy larger trucks need them and follow manufacturers guidelines. I wouldn't buy a 3/4 ton truck for a 19'-22 footer. And I think the GL itself would be a great match with a 23'....25' in my opinion, is the top end for the GL with wheelbase, etc.

To me there is no question of the GL having enough power and I have yet to find a German car that had bad brakes. In fact quite the opposite, but the GL cannot have it's wheelbase lengthened. Longer wheelbase is just a matter of physics in towing and part of an equation that often gets overlooked (conveniently or otherwise), which cannot be reinforced out of it. The GL wasn't designed per the manufacturer for more than 7500lbs. A 27' Airsream, loaded up deducting passengers and cargo found within the GL450 will exceed the GL's tow rating. Now if they pack super frugal and keep it under 7k to say 6800lbs, I still might not want that **myself** as a tow vehicle, particularly in the mountains.

[jcl]

Originally Posted by panamerican

I don't think folks over rely on vehicles that by the numbers that support the size and weights of trailers purchased. I think folks who buy larger trucks need them and follow manufacturers guidelines. I wouldn't buy a 3/4 ton truck for a 19'-22 footer. And I think the GL itself would be a great match with a 23'....25' in my opinion, is the top end for the GL with wheelbase, etc.

To me there is no question of the GL having enough power and I have yet to find a German car that had bad brakes. In fact quite the opposite, but the GL cannot have it's wheelbase lengthened. Longer wheelbase is just a matter of physics in towing and part of an equation that often gets overlooked (conveniently or otherwise), which cannot be reinforced out of it. The GL wasn't designed per the manufacturer for more than 7500lbs. A 27' Airsream, loaded up deducting passengers and cargo found within the GL450 will exceed the GL's tow rating. Now if they pack super frugal and keep it under 7k to say 6800lbs, I still might not want that **myself** as a tow vehicle, particularly in the mountains.

When we read "I bought a larger/heavier truck and now I can't even tell the trailer is back there" there is cause for concern. The heavier truck is damping out the feedback that is a key part of safe operation.

When we read "I bought a larger/heavier truck and now I can tow at 80 mph on the ball" (yes, that one is real) there is cause for concern. The heavier truck can provides false sense of security.

Sure, if one needs to carry 2000 lbs of cargo, a pickup or heavy van is likely the optimal choice. But the option exists to not take 2000 lbs of "must haves" along when camping. That doesn't mean that one has to be super frugal, just aware. And that awareness can lead to a higher level of safety than someone who purchases a heavy duty truck and is proud of never having weighed it, because "they don't have to think about it".

I would be more comfortable with the 27 than with a 25 with this tow vehicle, due to the potentially higher tongue weight with the 25 front bedroom model.

I wouldn't focus too much on wheelbase, as it will matter only in isolation. Better to calculate the ratio of rear overhang (ball to rear axle distance) as a percentage of wheelbase, IMO. A slightly shorter wheelbase, when combined with a much shorter rear overhang, can be more stable. The Ford extended vans have a long wheelbase, but a very long rear overhang, and so can be less stable than their non-extended counterparts. And we should consider how high the centre of gravity is when considering the stability of tow vehicles, whether hitched or unhitched.

[thewarden]

Originally Posted by panamerican

And for the record, Andy is referring him to a place that can do reinforcement.

I think the GL450 is a wonderful vehicle as is Cayenne and would drive them with passion any chance I got, and even tow a boat or 5000-6000lb trailer, but as with most vehicles, they are purpose built. The GL450 is outclassed by the numbers alone. You may drive a million miles safely towing your trailer with the suggested setup, but you may find on that one fateful day, when all the variables are aligned, your trailer will drive you, not the other way around. I've seen it so very many times on the interstate. Tail wagging the dog so to speak.

Yes, I understand that Andy is referring him to a place that can do reinforcement. And, if you know anything about his setups, one of the most important components is a short shank, which in my view is more critical than the reinforcements. The shorter the shank, the less leverage is placed on the receiver.

The net carrying capacity of a 27 FB is well over 1700 lbs for a total GVWR of 7600 lbs, which is right in the wheelhouse of a GL450. You do not need to be too frugal about loading your trailer to stay within 1700 lbs of cargo and an overall weight of 7500 lbs. So, where is the GL 450 outclassed by the numbers alone?

Now I know the truck crowd is all about nothing tows better than a truck. Well that isn't the case, especially from a safety perspective. Trucks are one of the worst handling and braking vehicles on the road, and despite all the hype from marketing teams of the Big 3 truck manufacturers, they are not well designed or engineered for towing. What they are good at is hauling, not towing.

Vehicles like the GL450, Cayenne, Touareg, BMW, etc., steer, handle and brake way better than a truck of any sort. Hooking up a 7000 lb trailer does not suddenly improve a trucks poor handling or braking. In an emergency braking or steering maneuver, I will take any of the above SUVs over a truck hands down.

Don't get me wrong, trucks are very useful and I love my GMC 3500 for hauling heavy stuff in the box and towing a fifth or gooseneck, but not towing a 7000 lb+ trailer with 1000 lbs+ on a ball way back of the differential.

[Shiny16]

Originally Posted by jcl

What an absurd comment.

The Fiat 500 has a payload of 800 lbs, which includes the driver and any passengers. Now think about the 1000 lb tongue weight. You can not tow a 27 foot Airstream with the Fiat 500. It isn't a matter of anxiety, it is a matter of physics.

What’s absurd is not seeing this was probably not meant to be taken literally.

So if it exceeds a spec on a Fiat 500 then why is ok to exceed a spec on a gl450?
Who gets to decide where to draw the line?

[Shiny16]

Originally Posted by thewarden

I agree, this is an absurd comparison. Technically, a GL450 is perfectly capable of towing the 27FB with no problem. And as far as the structural changes that some advocate to the hitch receiver, I am not sure this is necessary at all. The receiver on my Cayenne is rated for much less than the OPs GL, (770lbs compared to 900lbs). What I have gleaned from my research is the weight ratings on these hitch receivers is very subjective. As an example, earlier model Cayennes and VW Touareg receivers were rated at 604lbs while the later models were rated at 770lbs. They are identical in every way, (including the PNs), except for the weight rating sticker. In fact, VW will send you the 770 sticker to replace the other one if you ask.

I have towed my 27 FB with the Cayenne for many thousands of miles with no issues whatsoever and have always been able to stay within all of my weight ratings. I use the shortest shank possible, as advocated by Andy at CanAm, make sure my hitch is properly set up and I inspect the hitch receiver frequently while we travel and it has not moved a mm.

Yes, the GL will be close to it's limits but if you are mindful of what your are loading in the GL and the AS, and stay within load ratings, it will make an excellent tow vehicle for the 27GT

A Fiat on the other hand, cmon, there is absolutely no comparison. Absurd comparison indeed.

I don’t understand how you stay within the weight limits if the factory tongue weight of the 27 is already exceeding the limit on your Porsche.

[Shiny16]

I would be interested to know if the 1764 payload is from the door sticker or just the generic number.

[jcl]

Originally Posted by Shiny16

What’s absurd is not seeing this was probably not meant to be taken literally.

So if it exceeds a spec on a Fiat 500 then why is ok to exceed a spec on a gl450?
Who gets to decide where to draw the line?

The specs that matter are axle and tire weight ratings, and if you are a commercial carrier, the GVWR. Don't exceed those. That would be a good line to respect.

The tow rating, and the hitch rating, is another matter.

Since one can't fit one or two people, plus 1000 lbs (less what goes to the trailer) into the 800 lb capacity of the Fiat 500, it was an absurd comment.

The trailer is well within the ratings for the GL450. Strengthen the hitch if that is the limiting factor. Just respect the vehicle manufacturer's tire and axle weight ratings.

[Shiny16]

Originally Posted by jcl

The specs that matter are axle and tire weight ratings, and if you are a commercial carrier, the GVWR. Don't exceed those. That would be a good line to respect.

The tow rating, and the hitch rating, is another matter.

Since one can't fit one or two people, plus 1000 lbs (less what goes to the trailer) into the 800 lb capacity of the Fiat 500, it was an absurd comment.

The trailer is well within the ratings for the GL450. Strengthen the hitch if that is the limiting factor. Just respect the vehicle manufacturer's tire and axle weight ratings.

So you simply choose to ignore the hitch rating. So my questions is how do you decide what ratings you can ignore and by how much?

[Shiny16]

Anyway the OP asked for opinions. Mine would be no. It’s right at and slightly above some of the limits. If you don’t like this opinion there are many others to choose from.
You can either be conservative and go with the factory limits or you can trust the guy with the welding torch up in Canada. He seems to know what he is doing and is well respected by many on this forum. I’ll stick with the manual.

[out of sight]

FYI. Here is the towing placard on the GL/ML hitch. Note that a WD hitch is excluded from use and that the tongue load is limited to 600 lbs. So, if you tow a 27 with it, you will be exceeding the manufacturer's recommendations.

[thewarden]

Originally Posted by out of sight

FYI. Here is the towing placard on the GL/ML hitch. Note that a WD hitch is excluded from use and that the tongue load is limited to 600 lbs. So, if you tow a 27 with it, you will be exceeding the manufacturer's recommendations.

The OP does not have this hitch, he has an aftermarket Curt.

[Shiny16]

Interesting that it also says do not cut weld or modify. I guess they forgot to add “unless you know what your doing”. Or was that intentional?

[thewarden]

Originally Posted by Shiny16

I don’t understand how you stay within the weight limits if the factory tongue weight of the 27 is already exceeding the limit on your Porsche.

I am not exceeding any of the Cayenne's weight limits. If I was simply towing on the ball (without WD), I would be exceeding the rear axle and non WD capacity of the receiver. Receiver capacities are always higher when using WD and, when properly adjusted, all my weights are within load ratings, including front and rear axle ratings, cargo capacity of the Cayenne and the AS, GVWR of the Cayenne and AS, GTWR and the trailer towing capacity of the Cayenne.

[thewarden]

Originally Posted by Shiny16

Interesting that it also says do not cut weld or modify. I guess they forgot to add “unless you know what your doing”. Or was that intentional?

I am not a fan of modifying structural bits either, but it is hard to argue that Andrew and his folks have successfully modified/strengthened thousands of hitch receivers over the years. Although I have heard plenty of stories of failed factory installed hitches, and even seen a few myself, I have never heard a report of one of CanAms modified hitches failing. I am sure there is some sound engineering behind what they do, they have been around far too long to not have done so.

[Shiny16]

Originally Posted by thewarden

I am not exceeding any of the Cayenne's weight limits. If I was simply towing on the ball (without WD), I would be exceeding the rear axle and non WD capacity of the receiver. Receiver capacities are always higher when using WD and, when properly adjusted, all my weights are within load ratings, including front and rear axle ratings, cargo capacity of the Cayenne and the AS, GVWR of the Cayenne and AS, GTWR and the trailer towing capacity of the Cayenne.

I thought that the Porsche had a hitch weight of 700 or so. I also didn’t think that Porsche allowed the use of a WD.
Sometimes it seems like all the stuff cryptic.

[Shiny16]

Originally Posted by thewarden

I am not a fan of modifying structural bits either, but it is hard to argue that Andrew and his folks have successfully modified/strengthened thousands of hitch receivers over the years. Although I have heard plenty of stories of failed factory installed hitches, and even seen a few myself, I have never heard a report of one of CanAms modified hitches failing. I am sure there is some sound engineering behind what they do, they have been around far too long to not have done so.

I didn’t really mean to sound negative about CanAm. I know they have a great reputation. If I had any inclination to modify a hitch I would go to them. I’m just in the camp of not going beyond the manufacture ratings. I also don’t think you need a 50 percent cushion either.