Recommended SUV TV for a 30' Airstream

[gypsydad]

Originally Posted by 2012FB

Wow, case in point. There is so much gaslighting, and fear-mongering, if not BS on this site when it comes to towing.

Good grief, where does this come from? It is time to close this thread.

Or perhaps move on if it bothers you so much?

[gypsydad]

Originally Posted by pteck

I pointed out power for safety. Most don't understand or see the level of power or heat involved to tow. These can be gleaned from OBD-II monitors that I use below. For my 15k lb GCWR rig which is on the heavier end for a 27, or about what most 30ft rigs may weigh, it takes about 40-80hp to cruise on the freeway. Anything can do that job. Climbs with 3-4% grades need about 200HP to maintain fwy speeds. 5-6%, 300HP. 7%+, better bring 300++ hp. Most of the OPs cars are in the ~250HP range, and again, that'll do 30-40MPH in the big rig crawl lane on more demanding grades. Going to more interesting mountain destinations on mountain roads will have following drivers frustrated and doing perhaps unsafe things around you. And with that HP, you'll never want to pull off (if there's even a spot), because accelerating with grade and elevation can be even more concerning.

With HP and load, comes heat. Passenger vehicle drivetrains are no way designed for the extended outputs and heat associated with handling larger loads, nevermind loads well out of their design parameters. Here's a snippet of some key readings climbing a 6-7% grade.

Attachment 424034



Agreed with your comments. To expand..

Lightest is relative. I have a 27FB. It scales tongue weight at 1100-1200 lbs depending how full my tanks (propane, water, loadout) are. Static weights don't tell the story in regards to dynamic forces that larger trailers will impart. A unibody vehicle is not designed for a 30' task, even reinforced. It may do it, but will not have long term durability. Towing straight and easy is one thing, but engineers need to build structure have to consider well more than that, to also handle more severe maneuvers or dips, which may just permanently impact the structure not designed for it. If people were aware of the the thin gauge sheet metal that composes the rear of a unibody, with geometry not designed for tow or WD loads, you'd think twice. Towing a 25' AS with some key mitigations is one thing which I support, asking mid-weights to handle a 30' is a whole other proposition.

Excellent points you make...not sure some folks here agree, but certainly makes sense to a lot of us! Be safe; not sorry...don't overlook the design limitations mentioned here...as I mentioned earlier, doubt you will find "whomever" may have modified your vehicle to tow beyond it's original design specs is going to stand up for you should something happen. Call it "gaslighting" or what ever...ignorance is not an excuse, IMHO.

[4thWallDown]

Originally Posted by propchef

I tow within spec with a vehicle designed for it.

Saying your X5 was "designed for towing" is at best an overstatement.

You keep stating you are "within spec" but the numbers from BMW as published show that is unlikely with your 27' Airstream when on the road. The numbers on your X5 from BMW show 7.2k pounds towing cap and 1014/1016 pounds payload.

Unless you have modified your vehicle with some substantial upgrades to the frame, suspension and axles it seems that you are likely over spec when traveling as any current Airstream that is a 27' has a minimum published hitch weight of 850 pounds and a GVWR of 7600. I would bet your TW is well above 850 (static and sitting). Not sure if your 27' AS is 30 years old or not, so it could be far lighter as well.

We know that the published TW numbers for an AS are usually low and it isn't hard to reach the GVWR of the trailer (or in your case, reaching 7.2k pounds - what BMW says your towing cap is). Either way if the TW actually is 850 pounds, the payload allowance (people, hitch, gear and whatever) then is 164 or 166 pounds left over - and that is all while static and sitting on level payment. What about when moving? Is your AS always under 7.2k pounds?

What is the TW of your travel-loaded Airstream 27' (Sherline, etc.)?
What Class receiver do you have, and was in reinforced?
What does your door jamb sticker say is the payload for your X5?
What do the CAT scale tickets show for your X5 and AS?

[pteck]

Originally Posted by propchef

Agreed.

I'm on my second X5, the first was an e70. I still don't understand why folks claim it "wasn't designed to tow" when I paid for the factory towing package that includes larger brakes, an extra radiator, hitch receiver and associated electronics, and built-in anti-sway capabilities. It has as much power and brakes as many 3/4 ton vehicles. It has a short overhang and independent suspension, something every PU lacks. The weakest point of the system is the hitch receiver, something that can be overcome.

There's no issue with the vehicle being a unibody. I hear this often but have never seen any proof. Some of the BMW sedans suffered from metal fatigue in some of the suspension pickup points, but most of those vehicles are from the late 90's and early 2000s and are the M models, not the SUVs. Earlier model BMW SUVs (and many sedans) suffered from cooling issues and plastic radiator end caps that become brittle and fail. But again, these factory weak points can be identified and addressed.

I tow within spec with a vehicle designed for it.

People see what they want to see.

If you don't think the flex and bending of the hitch is not unibody damage, well, more power to you. This shortcoming is documented and well known even towing 25' AS with the BMW and the Cayenne sisters. Even at that level, without structural modification, a WD hitch can't properly transfer weight to the front axle, which is a real safety issue. Sure, modify that and people have. It's a compromise but it works and perhaps okay for something just out of guidelines. Understand the bending happens just for nominal towing. What do you think could happen if the bending occurred long enough? Or in a high force maneuver or incident?

To tow a 30' again, is a dramatically different proposition.

Thx to 4thWallDown for pointing out the caveat in the CanAm article at the bottom. I wonder if that wasn't put there after with all these emboldened individuals trying to hang a 30' off the rear, only to experience reality.

Something designed for it has to be considered as a system. It's not about how big the engine or subsystem is, but where the weakest link is.

That's not to say that the TVs in questions are weak. I've seen them make great tow vehicles for 25' ASs. 30', nope. Neither would I recommend others tow a 30' with my own model of vehicle.

[DewTheDew]

I will once again push back on the claim that BMW (or other companies such as Audi and Porsche) are unaware of towing in the US. Keep in mind that US sales of X5's are about 25% higher than European sales. BMW has engineers in the US. The X5 is BUILT in the US. They made conscious design choices and to imagine that they are ignorant of the towing situation in the US just makes no logical sense.

I would also push back on the claim that GAWR is fixed and GVWR is not. If you can find published statements from the company that says GVWR for their vehicle is just a guideline that can be exceeded and that GAWR is absolute then I will apologize and wholeheartedly support those claims. Not some random person who used to work for BMW, and not some inference, but their official company statement to that effect. Now, we can argue whether there are safety or legal consequences to crashing a vehicle that is loaded over the GVWR, but I think that for Andy to claim that GVWR is not an absolute is shady if he does not actually have factory statements to back that up (by each manufacturer).

Thanks for listening! I have no dog in this fight, and people may CHOOSE to do what they want, but they should do so with facts.

[jcl]

Originally Posted by DewTheDew

I will once again push back on the claim that BMW (or other companies such as Audi and Porsche) are unaware of towing in the US. Keep in mind that US sales of X5's are about 25% higher than European sales. BMW has engineers in the US. The X5 is BUILT in the US. They made conscious design choices and to imagine that they are ignorant of the towing situation in the US just makes no logical sense.

My X5 was some years back, and they came out with subsequent models, but that E53 model established the BMW SUV in North America.

BMW was totally aware of towing in the US. They just didn't design for it. I know from conversations with BMW that they weren't ignorant, they just weren't equipped to deal with it.

The factory engineers designed a "swan neck" hitch that is common in Europe, where the hitch ball in part of the ball arm. Not legal in North America, partly because of the 50 mm dimension, and partly because there was no place to attach safety chains. That hitch design was illustrated in the manuals to install the receiver. When BMW NA, which is the US marketing arm of BMW, needed a hitch with a 2" receiver, they didn't get it from the factory design team, they got it from a contract manufacturer in the NE US. They put the instructions to install it in the box, but used the Euro instructions. I still have them. There was no provision for a brake controller. Neither did they show a 2" receiver. When contacted, BMW suggested surge brakes, as used in Europe. Going into the LCM (lighting control module) under the dash, it was possible to install a new pin, and pick up a brake light signal. It wasn't possible to get it from the brake pedal, because of the specific brake light activation sensor. That ECM hack wasn't supported by BMW engineers. It wasn't possible to do that at the tail lights, since the lights were multiplexed and dashboard errors resulted. When it was pointed out to BMW product support engineers that surge brakes were not legal at the trailer weights being contemplated, they shrugged. They wanted to help. They just couldn't. As a tech resource on the largest X5 online forum, I explained to a lot of X5 owners how to install a hitch, a brake controller, and so on. For years.

There was another famous consequence of this local marketing organization figuring out how to offer a North American spec receiver. OEMs typically have a 15 year parts supply commitment. The parts may get expensive towards the end of that cycle, but they will be available. They are considered "supported parts". Because the North American sourced receiver did not come through BMW engineering, it did not attain that status. When the models changed, it was not kept in supply. There were many X5s of that generation that suffered rear crash damage, often minor, but enough to require a new receiver. But it was unsupported. Used receivers became very valuable in the aftermarket. BMW was asked why they didn't continue to supply the E53 receiver. The factory said they didn't' support it. The US marketing group that had sourced it didn't accept that they were bound by BMW engineering and design guidelines.

For the subsequent model of X5, the E70, they added a trailer brake controller part into their system (not factory, but in the parts system). Progress. Then with the next model after the E70, they discontinued that part. Back to the surge brake assumption. By that time it was possible to use a wireless brake controller. BMW didn't start acknowledging North American towing, they were just overtaken by technology. Good thing too. Because the vehicle towed very well, apart from not being offered with the equipment to make it straightforward to tow heavier trailers in North America.

They obviously designed the base vehicle for towing. They included electronic TSC (trailer stability control, supplied to them by Continental) starting in 2000 or so. Not as a factory option, but built into every X5 they produced. That was a decade before GM offered such a system, and there it was an option. The electronic trailer towing connection module (for trailer lights, just not brakes) told the computer to turn off the rear park sensors when a trailer connector was attached. It pointed the rear view camera down at the hitch. But it didn't allow for electric trailer brakes.

BMW engineers knew all about towing. They just did not have a mandate to make it legal in North America. Perhaps because all the design engineers were in Germany. The fact that the vehicle was manufactured in the US was secondary; it was designed and tested in Europe.

I don't know what BMW has done with trailer towing on the latest X5. I certainly hope it is better than the previous years. Four generations of X5s did not contemplate towing in the US, other than for light and un-braked trailers. On a subsequent generation, they even went to a receiver design that did not allow WD to be used safely, as it was designed to be detachable. Meanwhile, in Europe, the BMW factory engineered towing receiver became electrically activated, to move into towing position or hidden position. But that wasn't legal in North America, where they were still dealing with third party contract manufacturers to address the shortcomings of all the towing design from the factory being focused on European standards.

BMW vehicles are rated very highly for towing in Europe. In North America, the same vehicles which win tow vehicle awards in Europe come with advice from BMW North America that the vehicle is not designed for towing. They do not offer hitches, brake controllers, or tech support. I don't think it is that they are ignorant of towing, as much as it is that they simply made a decision not to focus on towing in North America. They don't see their customer base as requiring it. I think they are wrong, but it is their company.

[pteck]

Originally Posted by jcl

My X5 was some years back, and they came out with subsequent models, but that E53 model established the BMW SUV in North America.

BMW was totally aware of towing in the US. They just didn't design for it. I know from conversations with BMW that they weren't ignorant, they just weren't equipped to deal with it.

The factory engineers designed a "swan neck" hitch that is common in Europe, where the hitch ball in part of the ball arm. Not legal in North America, partly because of the 50 mm dimension, and partly because there was no place to attach safety chains. That hitch design was illustrated in the manuals to install the receiver. When BMW NA, which is the US marketing arm of BMW, needed a hitch with a 2" receiver, they didn't get it from the factory design team, they got it from a contract manufacturer in the NE US. They put the instructions to install it in the box, but used the Euro instructions. I still have them. There was no provision for a brake controller. Neither did they show a 2" receiver. When contacted, BMW suggested surge brakes, as used in Europe. Going into the LCM (lighting control module) under the dash, it was possible to install a new pin, and pick up a brake light signal. It wasn't possible to get it from the brake pedal, because of the specific brake light activation sensor. That ECM hack wasn't supported by BMW engineers. It wasn't possible to do that at the tail lights, since the lights were multiplexed and dashboard errors resulted. When it was pointed out to BMW product support engineers that surge brakes were not legal at the trailer weights being contemplated, they shrugged. They wanted to help. They just couldn't. As a tech resource on the largest X5 online forum, I explained to a lot of X5 owners how to install a hitch, a brake controller, and so on. For years.

There was another famous consequence of this local marketing organization figuring out how to offer a North American spec receiver. OEMs typically have a 15 year parts supply commitment. The parts may get expensive towards the end of that cycle, but they will be available. They are considered "supported parts". Because the North American sourced receiver did not come through BMW engineering, it did not attain that status. When the models changed, it was not kept in supply. There were many X5s of that generation that suffered rear crash damage, often minor, but enough to require a new receiver. But it was unsupported. Used receivers became very valuable in the aftermarket. BMW was asked why they didn't continue to supply the E53 receiver. The factory said they didn't' support it. The US marketing group that had sourced it didn't accept that they were bound by BMW engineering and design guidelines.

For the subsequent model of X5, the E70, they added a trailer brake controller part into their system (not factory, but in the parts system). Progress. Then with the next model after the E70, they discontinued that part. Back to the surge brake assumption. By that time it was possible to use a wireless brake controller. BMW didn't start acknowledging North American towing, they were just overtaken by technology. Good thing too. Because the vehicle towed very well, apart from not being offered with the equipment to make it straightforward to tow heavier trailers in North America.

They obviously designed the base vehicle for towing. They included electronic TSC (trailer stability control, supplied to them by Continental) starting in 2000 or so. Not as a factory option, but built into every X5 they produced. That was a decade before GM offered such a system, and there it was an option. The electronic trailer towing connection module (for trailer lights, just not brakes) told the computer to turn off the rear park sensors when a trailer connector was attached. It pointed the rear view camera down at the hitch. But it didn't allow for electric trailer brakes.

BMW engineers knew all about towing. They just did not have a mandate to make it legal in North America. Perhaps because all the design engineers were in Germany. The fact that the vehicle was manufactured in the US was secondary; it was designed and tested in Europe.

I don't know what BMW has done with trailer towing on the latest X5. I certainly hope it is better than the previous years. Four generations of X5s did not contemplate towing in the US, other than for light and un-braked trailers. On a subsequent generation, they even went to a receiver design that did not allow WD to be used safely, as it was designed to be detachable. Meanwhile, in Europe, the BMW factory engineered towing receiver became electrically activated, to move into towing position or hidden position. But that wasn't legal in North America, where they were still dealing with third party contract manufacturers to address the shortcomings of all the towing design from the factory being focused on European standards.

BMW vehicles are rated very highly for towing in Europe. In North America, the same vehicles which win tow vehicle awards in Europe come with advice from BMW North America that the vehicle is not designed for towing. They do not offer hitches, brake controllers, or tech support. I don't think it is that they are ignorant of towing, as much as it is that they simply made a decision not to focus on towing in North America. They don't see their customer base as requiring it. I think they are wrong, but it is their company.

This is simple from an engineering standpoint. BMW designed the X5 without requirements to support towing of larger trailers in North America. Therefore designs don't accommodate it, nor do they test, or validate it.

Without requirements, the design team does not holistically design and assess for detail requirements necessary to tow larger trailers in North America. No larger load carrying requirements of a hitch receiver. No weight distribution torsion requirements for the structures team. No brake controller interface requirements for the electrical team. And so on.

Which also means many of these structures can't properly handle such forces because engineers would be overdesigning, and said another way, not optimizing, for things that the design should do.

That the vehicle happens to tow well when modified is a wholly different thing than the car being designed for it. Using it is such a fashion is risk beared by the owner. I wouldn't push it too far.

[pteck]

Originally Posted by DewTheDew

I will once again push back on the claim that BMW (or other companies such as Audi and Porsche) are unaware of towing in the US. Keep in mind that US sales of X5's are about 25% higher than European sales. BMW has engineers in the US. The X5 is BUILT in the US. They made conscious design choices and to imagine that they are ignorant of the towing situation in the US just makes no logical sense.

I would also push back on the claim that GAWR is fixed and GVWR is not. If you can find published statements from the company that says GVWR for their vehicle is just a guideline that can be exceeded and that GAWR is absolute then I will apologize and wholeheartedly support those claims. Not some random person who used to work for BMW, and not some inference, but their official company statement to that effect. Now, we can argue whether there are safety or legal consequences to crashing a vehicle that is loaded over the GVWR, but I think that for Andy to claim that GVWR is not an absolute is shady if he does not actually have factory statements to back that up (by each manufacturer).

Thanks for listening! I have no dog in this fight, and people may CHOOSE to do what they want, but they should do so with facts.

As someone that designs and establishes thresholds for different systems. Thresholds and parameters aren't the magic numbers you think they are.

They are often expert interpretations from various forms of analysis that are then iterated upon, informed by requirements, tests, constraints, etc. They can often be overstated as much as it is understated. Supported by assumptions and various other variables, which sometimes can slide themselves. Then there's trades of expected use, duty cycle, lifecycle or change intervals, warranty, etc.

[4thWallDown]

Originally Posted by pteck

This is simple from an engineering standpoint. BMW designed the X5 without requirements to support towing of larger trailers in North America. Therefore designs don't accommodate it, nor do they test, or validate it.

Without requirements, the design team does not holistically design and assess for detail requirements necessary to tow larger trailers in North America. No larger load carrying requirements of a hitch receiver. No weight distribution torsion requirements for the structures team. No brake controller interface requirements for the electrical team. And so on.

Which also means many of these structures can't properly handle such forces because engineers would be overdesigning, and said another way, not optimizing, for things that the design doesn't need to support.

That the vehicle happens to tow well when modified is a wholly different thing than the car being designed for it. Using it is such a fashion is risk beared by the owner. I wouldn't push it too far.

x100k

Only thing I would change, if the X5 towing saga is accurate, would be as follows:

“BMW designed the X5 without requirements to support towing of larger trailers in North America”

to perhaps this:

“BMW designed the X5 without requirements to support the towing of any trailer in North America”

[propchef]

Originally Posted by pteck

People see what they want to see.

If you don't think the flex and bending of the hitch is not unibody damage, well, more power to you. This shortcoming is documented and well known even towing 25' AS with the BMW and the Cayenne sisters. Even at that level, without structural modification, a WD hitch can't properly transfer weight to the front axle, which is a real safety issue. Sure, modify that and people have. It's a compromise but it works and perhaps okay for something just out of guidelines. Understand the bending happens just for nominal towing. What do you think could happen if the bending occurred long enough? Or in a high force maneuver or incident?

To tow a 30' again, is a dramatically different proposition.

Thx to 4thWallDown for pointing out the caveat in the CanAm article at the bottom. I wonder if that wasn't put there after with all these emboldened individuals trying to hang a 30' off the rear, only to experience reality.

Something designed for it has to be considered as a system. It's not about how big the engine or subsystem is, but where the weakest link is.

That's not to say that the TVs in questions are weak. I've seen them make great tow vehicles for 25' ASs. 30', nope. Neither would I recommend others tow a 30' with my own model of vehicle.

Just for clarity, it's not a hitch, it's a receiver. The hitch goes into the receiver.

As mentioned I've been working on BMWs for years, towing with them, and I've never encountered the "flex" that you refer to, although the CanAm reinforcement is meant to eliminate that potential. As mentioned, some of the other models had had issues with suspension mounting points. We fix them and move on, we don't modify our driving habits because of it.
FIY, there was a member in one of the other groups who had his receiver ripped off the back of his PU truck pulling into an uneven driveway with his AS. The issue isn't necessarily the weight, but the torque from the WDH.

You've made some fairly demonstrative statements (bolded above) and I'm wondering if you can share your testing methods and subsequent results.

You're mostly arguing about the tongue weight, yet you propose that towing a 25' is OK, but not a 27 (28'), a trailer with a LIGHTER tongue weight.

I like how this conversation has gone from SUVs are not designed to tow, to they are not designed to tow in North America. What's next, not designed to tow in Kansas?

BMW has been winning towing awards for decades, and in Europe, they tow with the 5 series sedan as well. Here's a great video of the current (G05) BMW towing in Australia, where they do a LOT of towing and camping. It's the identical vehicle mechanically to the US and European models, although they have other options for powerplants, such as a diesel version that isn't available in the US. The tow specs are the same except for the 4-cylinder gas turbo and the hybrid. Note that they tow without WDH.

https://www.youtube.com/watch?v=ZfE470bpiyY

[propchef]

Originally Posted by 4thWallDown

Saying your X5 was "designed for towing" is at best an overstatement.

You keep stating you are "within spec" but the numbers from BMW as published show that is unlikely with your 27' Airstream when on the road. The numbers on your X5 from BMW show 7.2k pounds towing cap and 1014/1016 pounds payload.

The current X5 was indeed designed with towing in mind. The proof is in the subsystems and the fact you can no longer add an aftermarket system to get the same results as with previous X5 models. It's a complete system designed by BMW and installed at the time of manufacture. How is this an overstatement?

I've also stated within this thread that looking up numbers through Google is highly inaccurate, as each X5 is different. It's like comparing 0-60 times: fun but really not very accurate or helpful.

[pteck]

Originally Posted by propchef

Just for clarity, it's not a hitch, it's a receiver. The hitch goes into the receiver.

As mentioned I've been working on BMWs for years, towing with them, and I've never encountered the "flex" that you refer to, although the CanAm reinforcement is meant to eliminate that potential. As mentioned, some of the other models had had issues with suspension mounting points. We fix them and move on, we don't modify our driving habits because of it.
FIY, there was a member in one of the other groups who had his receiver ripped off the back of his PU truck pulling into an uneven driveway with his AS. The issue isn't necessarily the weight, but the torque from the WDH.

You've made some fairly demonstrative statements (bolded above) and I'm wondering if you can share your testing methods and subsequent results.

You're mostly arguing about the tongue weight, yet you propose that towing a 25' is OK, but not a 27 (28'), a trailer with a LIGHTER tongue weight.

I like how this conversation has gone from SUVs are not designed to tow, to they are not designed to tow in North America. What's next, not designed to tow in Kansas?

BMW has been winning towing awards for decades, and in Europe, they tow with the 5 series sedan as well. Here's a great video of the current (G05) BMW towing in Australia, where they do a LOT of towing and camping. It's the identical vehicle mechanically to the US and European models, although they have other options for powerplants, such as a diesel version that isn't available in the US. The tow specs are the same except for the 4-cylinder gas turbo and the hybrid. Note that they tow without WDH.

I am not studied on BMWs as much as you are. And surely there are differences in model years so maybe you can shed more light on this.

Here's a post I recall that documented such symptoms of flex.
https://www.airforums.com/forums/f46...ml#post1660675

I would caution those that are making recommendations based off of static tongue weights. To believe that a larger trailer that has lighter tongue weights would be easier on the TV - couldn't be farther from the truth. It's a generalization to follow tongue weight as other loads usually follow, but not always. Dynamic loads are multiple times more than any static weights. Then you have the other forms of loads like inertial, wind side loads, etc. Turning a larger trailer is going to involve more side forces. A longer trailer is going to catch for side windage. Hopefully not to exceed the TV stability. To your point, it not just weight, it's also WD torque. Forces manifest differently and systems need to account for and be designed for everyone of those types of loads.

Don't buy too much into the Australia market capacities. They are yet different again from Europe and the US.

[AlbertF]

An interesting conversation. A lot of the same comments could be made about Volvos. While they tend to recommend 1500 kg (3500 lbs) for North America, ratings in Europe are higher, but with low tongue weights.

I’ve towed Airstreams for close to 30,000 miles with two different Volvos. Neither has suffered any ill effects from towing, despite using receivers that attach to the rear subframe. Stability and comfort are first rate; there are no white knuckle drives. I’m sure a 3 or 5 series Bimmer would offer a similar experience.

FWIW, I’m not worried about damage to our present tow vehicle. It has over 200,000 miles on it, the driveline is showing no signs of wear, and it still drives well. If a major component were to fail, I’ve already gotten my money’s worth! Yes, I am contemplating a replacement, and a used V60 wagon is at the top of my list.

I appreciate the engineering perspective. It provides food for thought. However, 16 years of experience has not dissuaded me in the least!

[richard5933]

There have been lots of mentions of towing limits in Europe being such and such.

Important to keep in mind that the speed limits for towing a caravan in the EU are MUCH lower than in the US. The likelihood of bad things happening while towing can be greatly reduced by slowing down, so perhaps that explains why the towing capacities there are different.

[propchef]

Originally Posted by pteck

I am not studied on BMWs as much as you are. And surely there are differences in model years so maybe you can shed more light on this.

Here's a post I recall that documented such symptoms of flex.
https://www.airforums.com/forums/f46...ml#post1660675

I would caution those that are making recommendations based off of static tongue weights. To believe that a larger trailer that has lighter tongue weights would be easier on the TV - couldn't be farther from the truth. It's a generalization to follow tongue weight as other loads usually follow, but not always. Dynamic loads are multiple times more than any static weights. Then you have the other forms of loads like inertial, wind side loads, etc. Turning a larger trailer is going to involve more side forces. A longer trailer is going to catch for side windage. Hopefully not to exceed the TV stability. To your point, it not just weight, it's also WD torque. Forces manifest differently and systems need to account for and be designed for everyone of those types of loads.

Don't buy too much into the Australia market capacities. They are yet different again from Europe and the US.

How so? What, specifically are the subframe, suspension, braking, and cooling differences? Why would BMW engineer a different version of an existing vehicle for each market? The quick answer is they don't. It's the same vehicle.


Thanks for the link. That thread discusses the E70, the same model jcl had and the model I had previous to our current G05. That was 2 generations ago, and the hitch in question is an aftermarket piece and wasn't installed at the factory. None of them were for the NA market. Mine is a factory option, done at the time of the build.

Among BMW guys the diesel version of the E70 is legendary for it's towing abilities and rock-solid stance. My good friend still uses his to take his GT3 back and forth to the track.

[propchef]

Originally Posted by richard5933

There have been lots of mentions of towing limits in Europe being such and such.

Important to keep in mind that the speed limits for towing a caravan in the EU are MUCH lower than in the US. The likelihood of bad things happening while towing can be greatly reduced by slowing down, so perhaps that explains why the towing capacities there are different.

Yes, the limits are lower there and in CA, where any vehicle being towed is limited to 55, a limit I adhere to with the exception of portions of I-5 in NORCAL. The speed limit there for everyone else is 70 and the speed differential makes me nervous. I speed up to 62.

[pteck]

Originally Posted by propchef

How so? What, specifically are the subframe, suspension, braking, and cooling differences? Why would BMW engineer a different version of an existing vehicle for each market? The quick answer is they don't. It's the same vehicle.


Thanks for the link. That thread discusses the E70, the same model jcl had and the model I had previous to our current G05. That was 2 generations ago, and the hitch in question is an aftermarket piece and wasn't installed at the factory. None of them were for the NA market. Mine is a factory option, done at the time of the build.

Among BMW guys the diesel version of the E70 is legendary for it's towing abilities and rock-solid stance. My good friend still uses his to take his GT3 back and forth to the track.

What's different is the use case and trailer types. That's very important for system designs.

The US is the only market of the 3 that regularly uses WD hitches. It's a niche in other markets. The trailers are designed with that in mind. Fundamentally, it's because we generally tow at higher speeds. As a result, the architecture, weight, and weight distributions of travel trailers designed in each market is different. Axle placement is different. Tongue length ratio is different. Hitch and lashups are different. These application differences result in capacity spec differences.

None of this takes away from how good the X5 may be. It doesn't take away that your friend tows his GT3 well. Yet a car carrier is far far different from a travel trailer in terms of dynamics. And it certainly is not a 30' AS.

Every owner can expound on how great their own vehicle is. For their own application. But that may or may not meet everyone else's needs objectively or subjectively. I will say it will not pass muster for a manufacturer however which has to account for all user types.

[4thWallDown]

Originally Posted by propchef

I've also stated within this thread that looking up numbers through Google is highly inaccurate, as each X5 is different. It's like comparing 0-60 times: fun but really not very accurate or helpful.

You keep stating this, but earlier in this thread I posted the actual factory specs (#121) as provided by BMW for your X5 and yet you say "The internet is wrong, Google is wrong, etc."

Despite your inside knowledge that the internet and Google are wrong (even when the info is coming from BMW's own sites, owner's manuals, etc.), and having been asked 2 or 3 times and having your suspected numbers addressed each time, you still refuse to post your numbers, door jamb sticker and actual weights:

Originally Posted by 4thWallDown

Wow, this is interesting. Not sure what year or model Airstream you have at 27', but the 2023 FB International at 27' lists a GVWR of 7600 pounds - which is 400 pounds more than the 2022 BMW X5 listed towing cap at 7,200 pounds. Those are scary numbers.

The tongue weight of the 2023 FB International 27' lists at 850 pounds (which as we all know for Airstream may be low). Anyway, even if it was 850 pounds the payload cap for a 2022 X5 is listed at 1014 or 1016 pounds. So if it was a 2023 Airstream and a 2022 X5 you would have a whopping 166 pounds of payload left over with that setup. Those are scary numbers.

Your numbers must be somehow way different than those above if your X5 "doesn't blink" "on 8% grades" pulling a 27' Airstream. Autonomous and driverless modification as well? WD hitch that is higher cap/shift than most?

Originally Posted by 4thWallDown

No need to have any "debate" here, as the facts are clear - unless of course BMW is lying in their own manuals and literature.

The stated numbers provided by Airstream and BMW show (for your BMW and really any 27' Airstream) you are very likely at or over the limits, including tongue weight, brake capacity and payload (and likely transmission, cooling and suspension acceptable limits as well). Some sites actually show less for towing and payload:


https://www.caranddriver.com/bmw/x5/specs:

Maximum Towing Capacity (pounds): 6603

Maximum Trailer Weight, dead weight hitch (pounds): 5000

Maximum Tongue Weight, dead weight hitch (pounds): 500

Maximum Trailer Weight, weight distributing hitch (pounds): 6603

Maximum Tongue Weight, weight distributing hitch (pounds): 660


https://www.unitedbmw.com/manufactur...bmw-x5-towing/


BMW X5 sDrive40i – 3.0L Twin-Turbo I6 Engine

• 7,200 pounds maximum towing capacity
• 1,014 pounds payload capacity
• 4,828 pounds curb weight

https://www.bmwseattle.com/2022-bmw-x5-towing-capacity/

Same numbers as above.


BMW:

With a towing capacity of up to 7,200 pounds......

The 2023 X5 Owner's Manual relevant sections are attached. The max TW is 551 pounds as you can see. Additionally, BMW provides the numbers and some are in fact are lower than what was quoted.

How much does your Airstream weigh? Tongue weight? Actual payload when towing? Have you ever taken your fully loaded setup to the scales? Sherline for tongue? Would love to see those numbers.

Until then, please let me know in advance when and where you will be on the road.

I hope that BMW and Airstream are just plain wrong about it all and that you are towing safely and within your limits!

Originally Posted by 4thWallDown

So you pull your 28' with a BMW X5 as you said, but you still haven't addressed the issues raised in Posts 117 and 121 that show you could easily be (or are) at or over your towing capacity, TW, brake capacity and payload or even all four at once.

Originally Posted by 4thWallDown

You keep stating you are "within spec" but the numbers from BMW as published show that is unlikely with your 27' Airstream when on the road. The numbers on your X5 from BMW show 7.2k pounds towing cap and 1014/1016 pounds payload.

Unless you have modified your vehicle with some substantial upgrades to the frame, suspension and axles it seems that you are likely over spec when traveling as any current Airstream that is a 27' has a minimum published hitch weight of 850 pounds and a GVWR of 7600. I would bet your TW is well above 850 (static and sitting). Not sure if your 27' AS is 30 years old or not, so it could be far lighter as well.

We know that the published TW numbers for an AS are usually low and it isn't hard to reach the GVWR of the trailer (or in your case, reaching 7.2k pounds - what BMW says your towing cap is). Either way if the TW actually is 850 pounds, the payload allowance (people, hitch, gear and whatever) then is 164 or 166 pounds left over - and that is all while static and sitting on level payment. What about when moving? Is your AS always under 7.2k pounds?

What is the TW of your travel-loaded Airstream 27' (Sherline, etc.)?
What Class receiver do you have, and was it reinforced?
What does your door jamb sticker say is the payload for your X5?
What do the CAT scale tickets show for your X5 and AS?

You keep going on and on about the X5 (US, Europe, diesels, old, new or whatever). If your X5 is the Ultimate Towing Machine, then your doorjamb stickers, and actual and loaded numbers for the X5 and the 27' Airstream should back this up.

After all, numbers don't lie but in this situation they apparently don't even exist.

[jcl]

Originally Posted by pteck

This is simple from an engineering standpoint. BMW designed the X5 without requirements to support towing of larger trailers in North America. Therefore designs don't accommodate it, nor do they test, or validate it.

Without requirements, the design team does not holistically design and assess for detail requirements necessary to tow larger trailers in North America. No larger load carrying requirements of a hitch receiver. No weight distribution torsion requirements for the structures team. No brake controller interface requirements for the electrical team. And so on.

Which also means many of these structures can't properly handle such forces because engineers would be overdesigning, and said another way, not optimizing, for things that the design should do.

That the vehicle happens to tow well when modified is a wholly different thing than the car being designed for it. Using it is such a fashion is risk beared by the owner. I wouldn't push it too far.

My X5 was not modified in any way for towing. The vehicle was fine. The modifications were to receiver hitches on later generations of the X5, which wasn't designed in Europe, but by a marketing organization in the US. My receiver wasn't designed for the bending loads associated with WD hitches, but the vehicle was designed to withstand them just fine. I would agree that BMW did not likely validate WD loading, as they made no comment on it, for or against. They also didn't list a tow rating for my vehicle when sold in North America, the only tow rating was on a label that came with the OE receiver hitch kit. That rating was widely reported as the vehicle tow rating, but it only applied to the OE receiver.

Separately, the vehicle was not provided with an electric brake controller, and dealers didn't know how to install one.

It is worth understanding how the X5 unibody structure was designed to support a trailer hitch receiver.

The BMW installation required that the bumper, and bumper carrier be removed. Then, the collapsible struts that deformed when the vehicle was in a rear end collision, were removed. They were replaced with solid mounts that tied into the unibody in three separate planes on each side, bolted from the rear, underneath, and down from the luggage area. The BMW receiver was mounted to this structure. It was grossly overbuilt for the typical loads applied to Euro hitches, and was completely adequate for North American trailers with WD hitches, although I am sure it was not tested by the factory engineers for that use.

The first one that was taken to CanAm for reinforcement was in 2000. It was documented on this site by poster withidl. They looked at it, and advised that the receiver (not the vehicle, but the receiver and mounting structure) were built like a one ton truck, and would be fine. I concluded the same when I installed my hitch.

Aftermarket hitches were offered that did not include the same mounting system, but simply bolted to the rear pan. They deformed, as that was an inadequate design. They didn't necessarily deform with WD equipment, it usually happened with a cargo carrier that exceeded the BMW load spec (which specified a tongue weight, and a maximum offset distance from the pin, thus limiting the bending moment). Those hitch manufacturers modified their receivers to include a longitudinal strut, very similar to the Can Am design approach, but not as neat, and with less ground clearance as a result.

The first picture shows the mounting of the OE receiver to the box sections in the unibody that are there to withstand rear crashes.

The second picture shows the BMW OE hitch, in this case the NA version with a 2" receiver. Both used the same mounting system.

The third picture shows the type of aftermarket hitch that did not address the bending loads, and which could fail. People that this happened to were often incredulous that their hitch bent upwards, not down. They didn't understand WD loading. One is documented in a post just above.

The fourth photo shows the updated aftermarket hitch design, with an improved (stronger) mounting system, to resist bending loads. Similarities can be seen with the CanAm approach of spreading the mounting points to accommodate bending loads. This design is sold by Hidden Hitch, Draw-Tite, and Curt, all reputable hitch manufacturers, among others.

When BMW went to the next generation of the X5. the E70, they eliminated the OE mounting struts, and that hitch is shown in the fifth photo. It simply mounted to the vertical surface behind the bumper, with no reinforcing struts. These are the hitch receivers that are routinely modified to accommodate WD loading. Looking at that 5th photo, the limitations of the OE receiver are clearly apparent if one wants to use WD equipment.

The next generation of X5 got a North American version of the European hidden hitch, with detachable ball and arm, shown in photo 6.. These hitches are in no way suitable for use with WD. There is an optional 2" receiver bracket that plugs into the vertical socket, but it cannot resist bending loads and is suitable only for a lightweight bike carrier.

I understand that the latest generation of the X5 has a more appropriate and sturdier receiver hitch, but I haven't worked on one of those models.

My generation of X5 had a standard tow rating of 7700 lbs, with a no cost factory option of a higher tow rating, 8500 lbs IIRC. I suspect that is what BMW engineers tested the tow rating to, but it was likely derated to 7700 lbs (3.5 tons) to meet Euro regulations re operator and vehicle licensing. If the owner wanted to deal with the increased hassle of keeping log books, and paying higher registration fees, they could request the higher rating. In North America, BMW offered a 6000 lb capacity receiver hitch kit, and that is the only place they referenced a North American tow rating, it isn't in the owner's manual or technical literature, let along the door jamb.

Interestingly, that BMW receiver kit offered owners a potentially higher tow rating for some trailer types, such as boat trailers and glider trailers, which I suspect had lower tongue weights. The tech description of that offer is shown in photo 7, from the tech literature. I never requested a higher tow rating.

It can be seen that the issue is the receiver design, not the vehicle. This is not often well understood by those who refer to vehicle modifications on the X5, and often suggest that the unibody structure itself is the weak point. It simply isn't. Further insight into the strength and durability of the unibody can be gleaned from the history of BMW entering the X5 in the Paris Dakar, both as a race entrant and as a support vehicle for BMW motorcycles.

[jcl]

Originally Posted by 4thWallDown

After all, numbers don't lie but in this situation they apparently don't even exist.

I think relying on C&D numbers is an example of being a Google researcher. For my BMWs, I relied on the BMW TIS, an online tech resource for dealers that was available by subscription. It is lapsed, as I sold my last BMW. I still have it, just not for current production models.

I would note that my experience with BMW was that the door jamb label did not provide an absolute payload capacity. For that model, BMW appears to have used a standard label for all models of that vehicle. That capacity was published online, in marketing materials, and so on. I wondered about the absolute payload of my last tow vehicle, since I had a loaded model with all options except nav, and including the panoramic sunroof. I had significantly more calculated payload than the label, based on the specific GVWR and scaling the vehicle. I concluded that BMW didn't see maximizing published payload as a marketing advantage, and so saved money by printing a single label. There may be another reason, that is just speculation. But it is worth noting because an extreme focus on published numbers is not necessarily useful with these vehicles.

With another BMW I owned, the factory published a hp figure that was suspect. It didn't make sense based on the vehicle performance. Putting the vehicle on a chassis dyno produced a hp figure (corrected for temperature and altitude) than BMW claimed at the flywheel. Apparently there is no consumer law against understating characteristics such as these, just against overstating them.