Pulling with BMW X5i

[jcl]

https://www.getbmwparts.com/oem-part...ll-82712414452

I would confirm your VIN when you order. It appears they are using the same part number for various size balls. Likely with the ball diameter as a descriptor. Or, they updated the part numbers. There is often less part number discipline with accessory parts than vehicle parts,

Note that this ball mount costs about the same as a full Curt hitch rated for WD.

Edit: when I go back to your link, there are two items labelled #3. One is the 2 5/16 ball.

[SYC2Vette]

Originally Posted by jcl

https://www.getbmwparts.com/oem-part...ll-82712414452

I would confirm your VIN when you order. It appears they are using the same part number for various size balls. Likely with the ball diameter as a descriptor. Or, they updated the part numbers. There is often less part number discipline with accessory parts than vehicle parts,

Note that this ball mount costs about the same as a full Curt hitch rated for WD.

Edit: when I go back to your link, there are two items labelled #3. One is the 2 5/16 ball.

Awesome thanks perfect, now back to the BMW dealer who said the 2" was the only one listed ??

[dog_tired]

Check out this thread:
https://www.airforums.com/forums/f23...rt-181085.html

I went through the same nightmare with BMW dealer. You need to get an aftermarket hitch installed and allow BMW to install the wiring harness for towing. Then purchase a brake control unit (wireless) and you'll be fine. Just don't let BMW install anything other than the wiring harness for towing.

[SYC2Vette]

Originally Posted by dog_tired

Check out this thread:
https://www.airforums.com/forums/f23...rt-181085.html

I went through the same nightmare with BMW dealer. You need to get an aftermarket hitch installed and allow BMW to install the wiring harness for towing. Then purchase a brake control unit (wireless) and you'll be fine. Just don't let BMW install anything other than the wiring harness for towing.

Thanks! that thread was helpful. He is most likely going with a 16' so no need for WD and all that would involve. We have purchased the 2" and 2 5/16" for the BMW installed hitch assembly and he is having the dealer install the entire trailering package. Apparently the M rear brakes (in this case X6M) may be the only difference between 6,000 lb and 7,200 lb tow rating but at any rate he will be well below 6,000, and well below the 3,550 lb rear axle GAWR.

[dog_tired]

Sounds like you're getting it set up then.
Only other comment is that U-Haul's cost to install the hitch could be significantly less than the labor cost you pay to BMW. It's worth looking into.
Happy Trails.

[tizeye]

As a side note...most of the discussion is already owning an X5 and retrofitting with dealer and other installs, all of which the manual reduces the towing capability to the 6000 range. In the case of purchasing new, the last thing you want is a 'dealer install' as part of the deal, even using 'BMW' parts vs an actual factory install. The problem is, few are ordered with the $500 option, and worse, the BMW website excludes "towing hitch" from a search limiter. The competition (Mercedes, Audi, Porsche does likewise, so not blaming BMW or anything like that) and have to search car, by car, by car for towing package. But...I found a solution. Search on cars.com, expanding radius out a comfortable distance since so few cars, and after the initial return, can further refine the search with the "towing/hitch" limiter. While you can proceed from there, I prefer to go to the identified dealer's website and bring it up in their inventory. Since it is a cars.com web design, also works with searches of competing brands to narrow those down. One thing to note on BMW, factory installed hitches have a totally different bumper trim design, bringing the hitch into it, compared to the normal straight trim design.

[matthewk]

Originally Posted by tizeye

As a side note...most of the discussion is already owning an X5 and retrofitting with dealer and other installs, all of which the manual reduces the towing capability to the 6000 range. In the case of purchasing new, the last thing you want is a 'dealer install' as part of the deal, even using 'BMW' parts vs an actual factory install. The problem is, few are ordered with the $500 option, and worse, the BMW website excludes "towing hitch" from a search limiter. The competition (Mercedes, Audi, Porsche does likewise, so not blaming BMW or anything like that) and have to search car, by car, by car for towing package. But...I found a solution. Search on cars.com, expanding radius out a comfortable distance since so few cars, and after the initial return, can further refine the search with the "towing/hitch" limiter. While you can proceed from there, I prefer to go to the identified dealer's website and bring it up in their inventory. Since it is a cars.com web design, also works with searches of competing brands to narrow those down. One thing to note on BMW, factory installed hitches have a totally different bumper trim design, bringing the hitch into it, compared to the normal straight trim design.

I agree, for such an inexpensive option, I cannot understand why dealers don't option them. Same with the spare tire, should always be included @ $150.

There is a dealer close to Chicago which seems to option many of their cars with the hitch. Bill Jacobs, I bought mine there, drove from Cleveland.

[bono]

Easy explanation - not many BMW customers use hitch. Many US specs cars do not even have the hitch option, even though in Europe they are used for towing larger trailers.

No spare tire - easy money for dealer. They install run flats, tell people that they can drive on flat and / or they cannot patch run flat. Therefore, most flats result in a new tire(s) installed at dealer.

Originally Posted by matthewk

I agree, for such an inexpensive option, I cannot understand why dealers don't option them. Same with the spare tire, should always be included @ $150.

There is a dealer close to Chicago which seems to option many of their cars with the hitch. Bill Jacobs, I bought mine there, drove from Cleveland.

[adamkalins]

Originally Posted by jcl

Note that there are multiple generations of each of the X3 and X5, with different powertrains. Your earlier X3 was noted to be a 2.5, which is a naturally aspirated engine and would lose power at altitude, the same as any naturally aspirated engine. A turbocharged engine compensates for altitude, so the power degradation is much less.

My X3 had the 3.0si 260 hp engine, more than most X5 diesels, and more than my X5. It was rated to tow 3500 lbs as that was the rating of the OE receiver; the vehicle was the same weight and size as my earlier X5, but with 35 more hp.

You taught me that the turbo compensates for altitude. Thank you. I never considered that, but it totally makes sense. Oxygen sensors and blowers and all, pushing the correct amount in.

[adamkalins]

Originally Posted by jcl

With my X models, I was able to install the BMW wiring interface module independent of the choice of hitch receiver; I recommend the BMW electrical interface whatever receiver is used.

The trailer stability control (TSC) is already built into the vehicle stability control system (DSC, on my model). The BMW wiring interface just activates it.

I too recommend the X5 wiring harness for the Dynamic Stability Control. I should add that I watched them install mine, and a separate processor was inserted in my car. They plugged it in. The car was mostly ready for this module, but just to be clear, my upgrade was more than a wire loom. They added a module.

[knight-rider]

Bono touched on an important point, which is "not many US ustomers use hitch", and so not much data is available to tune the tow vehicles. That's the root cause of confusion around German cars' towing limits in US market. Every automobile tuning happens based on data and customer inputs. This is the only reason I lean towards buying a vehicle that has been used for towing for decades. It's unfortunate to see these threads on German cars towing capability eventually leads into - (1) they are extremely unsafe if you exceed the sticker specs (2) they are unreliable and expensive (3) buy a bigger tow vehicle.

The specs are there for two reasons - (1) Liability (2) Vehicle's limitation based on what the manufacturer installed; the numbers are based on science and physics. I come from a world where open heart surgeries are performed on automobiles, and when done with good quality, then there is no such thing as "sub optimal" or "Band-Aid". It's called an UPGRADE. If you take a car and replace windows/windshield with bullet proof glass, it's not a hack or workaround. It's a legit upgrade; the windows become bullet proof to some degree.

If you reinforce the hitch, and if your TV suspension can take the load, and if you are under your axle load, and if your TV's weight/wheelbase are proportional, then it's a legit upgrade and tongue weight can be safely exceeded beyond the specs. Some experts don't count wheelbase/TV's weight. I toss it into the mix because of physics and science. If you start replacing part by part and make your TV more powerful - suspension, hitch, tires, frame reinforcement, etc. - it's all legit upgrade as long as the work is of high quality. Obviously it's not a good financial decision, but if you are Bruce Wayne, then go for it. Look at how manufacturers change spec numbers - my previous Lexus base model was 1500 lbs towing. But I had added tow package (adds transmission cooler, same engine, and pre-wiring), and the number jumped to 3500 lbs towing. Safety is of paramount importance to me. I ride a powerful motorcycle that goes 0 to 60 in less than 3 secs. I wear a full airbag race suit while riding in city streets around grocery stores. People might laugh at my attire, and my family/friends think I'm crazy, which might be true, but I take safety very seriously, because I have seen some personal tragedies. So there is no such thing as "overkill" when it comes to safety; however, I absolutely don't believe that the solution to German SUV towing is to NOT tinker around. Liability is definitely a concern if something happens, but safety wise, if you trust the mechanic who is doing it, and if there is data to prove his/her work, and if you and your TV feels confident handling your trailer, then it's reasonably SAFE. Most importantly, you need to know what you are doing. Safety is not binary. The work that CamAm Andy is doing since several decades is very promising. He has helped hundreds of BMW/Porsche/WV/Audi owners tow safely. He hasn’t heard a single incident of drivers going off the rails or having accidents because the rig was unsafe.

The problem is some people blindly tow without considering vehicle's capability (other than towing capacity) and without any TV upgrades because they saw someone in YouTube with the same car towing a bigger trailer. That's the recipe for disaster, because they are putting everyone's life at risk.

To the OP - I suggest taking your rig to CAT scale with your usual load. If your rear wheel well sag is not more than 0.5" compared to front wheel well, and if all your axle loads are below limits (based on the sticker on your door), then your rig is reasonably safe. No rig is 100% safe. The way you load the trailer, the traction on the tires, drivers' judgement, weather, and several other factors count. If you are driving in a steep terrain, please make sure you have good traction. Even if you are in the safest vehicle in the world, if you don't have good traction, then you are up for a disaster. This applies to Batmobile as well!

[knight-rider]

Originally Posted by knight-rider

Bono touched on an important point, which is "not many US ustomers use hitch"

Typo - I meant "not many BMW US customers use hitch"..

[BayouBiker]

Originally Posted by knight-rider

Bono touched on an important point, which is "not many US ustomers use hitch", and so not much data is available to tune the tow vehicles. That's the root cause of confusion around German cars' towing limits in US market. Every automobile tuning happens based on data and customer inputs. This is the only reason I lean towards buying a vehicle that has been used for towing for decades. It's unfortunate to see these threads on German cars towing capability eventually leads into - (1) they are extremely unsafe if you exceed the sticker specs (2) they are unreliable and expensive (3) buy a bigger tow vehicle.

The most useful data regarding safety and performance comes from the OEMs own testing because they are able and willing to test to failure. Customers are not. Most of the customer feedback has to do with passenger comfort and perception, vehicle driving experience and damage reports. The evidence seems to contradict bono's narrative.

If you reinforce the hitch, and if your TV suspension can take the load, and if you are under your axle load, and if your TV's weight/wheelbase are proportional, then it's a legit upgrade and tongue weight can be safely exceeded beyond the specs.

This statement is incomplete. Combination stability against sway and oversteer also must be confirmed before it is safe to exceed specs. Safety is the most important but least well understood and most overlooked aspect of towing specifications.

(snip...) So there is no such thing as "overkill" when it comes to safety; however, I absolutely don't believe that the solution to German SUV towing is to NOT tinker around.

How does the home garage tinkerer or even a professional hitch installer confirm vehicle capability against static and dynamic instability when towing after they are done tinkering?

Liability is definitely a concern if something happens, but safety wise, if you trust the mechanic who is doing it, and if there is data to prove his/her work, and if you and your TV feels confident handling your trailer, then it's reasonably SAFE.

What documentation and data does a mechanic provide that the upgraded vehicle does not have a problem with oversteer when towing at 70 mph? A combination pulled gently around the roads or even subjected to slalom courses at speeds well under critical speeds won't display any indication of the inherent static or dynamic instabilities unless they are specifically tested for them.

Most importantly, you need to know what you are doing. Safety is not binary. The work that CamAm Andy is doing since several decades is very promising. He has helped hundreds of BMW/Porsche/WV/Audi owners tow safely. He hasn’t heard a single incident of drivers going off the rails or having accidents because the rig was unsafe.

And yet hitch installers and trailer dealers stubbornly refuse to test the vehicles for indication of instability. I think I know why that is. Also it is not true that customers have not had crashes and have not experienced sway and oversteer due to overloading and towing beyond vehicle capacity.

[jcl]

Originally Posted by BayouBiker

And yet hitch installers and trailer dealers stubbornly refuse to test the vehicles for indication of instability. I think I know why that is.

I would have phrased it as them refusing to engage with keyboard warriors. They are perfectly capable of testing. My experience was that a personal visit and a discussion revealed more than simply reading posts.

[BayouBiker]

Installers are quite capable of testing for sway and oversteer, I agree, thanks for pointing that out! They could have been doing so for better than 50 years when the issues first came into prominence and long before the internet or Airstream Forum, but they don't. Vehicle manufacturers do however test for both kinds of instabilities and several other important conditions. They then include the results as strong factors in setting towing guidance. The approach is a best practice that installers might want to take to heart.

[knight-rider]

Originally Posted by BayouBiker

Most of the customer feedback has to do with passenger comfort and perception, vehicle driving experience and damage reports.

I disagree. Your vehicle collects far more data than you can imagine. If you don't believe, then ask a Tesla engineer. They have built an empire on the data collected from customers. They have every possible data to tune the car, and to make the cars the safest vehicles on the planet. No wonder their stocks are going crazy. OEMs use field data all the time to tune the cars every year to make them safe and powerful. This has been happening since ages. That's why Porsche 911 turbo S is one of the finest machines on a race track, and Ford 350 is one of the sturdiest vehicles to haul tons of load. German SUVs don't bother to gather towing data much because they don't care. They are not targeting towing customers explicitly in US (at least for now). That's what Bono was hinting at.

Originally Posted by BayouBiker

Combination stability against sway and oversteer also must be confirmed before it is safe to exceed specs.

Let me summarize. If you have a German car with tow capacity of 7500 lbs towing 7300 lbs trailer with below setup

• Reinforced hitch

• WD + suspension tuning to create no more than 0.5" delta between front and rear wheel wells

• axle loads below the specs

• Propride or Hensley hitch to eliminate sway

then you won't seen an oversteer at 70 mph BECAUSE of your setup. User error can cause oversteer (uneven load in trailer or no traction) and that could happen with any vehicle.

I don't understand how a German SUV weighing 5000 lbs and towing 7300 lbs trailer with rock solid setup like above can oversteer at 70 mph but a heavy duty vehicle weighing 7000 lbs and towing 14000 lbs trailer won't oversteer under the same circumstances.

If you still don't believe, then please rent a German SUV with above setup (if you can find), and tow around at 70 mph, and you'll experience it first hand. I can confidently say there is no oversteer with above setup because I have tried above setup in PNW mountains during winter storm on I5 (rain + heavy cross winds). The only thing I was missing was Hensley/Propride hitch.

Originally Posted by BayouBiker

How does the home garage tinkerer or even a professional hitch installer confirm vehicle capability against static and dynamic instability when towing after they are done tinkering?...

And yet hitch installers and trailer dealers stubbornly refuse to test the vehicles for indication of instability.

Please check out all the videos in this link (all of them) - https://www.canamrv.ca/towing-expertise/videos/


Porsche holds a Guinness world record for towing Airbus A380. I'm sure A380 weighs more than 7300 lbs, and it's tongue weight exceeds OEM specs (617 lbs).

https://www.guinnessworldrecords.com...-record-470529

I'm a safety freak. I don't want to share the personal reasons on why I care about it so much, because this is not the forum to share personal tragedies. But I research about safety before even considering anything else. Safety is complicated - external factors, vehicles' capability, and driver's common sense, all play into it. Making a blanket statement that German cars are unsafe because they are cutting close to OEMs specs is an exaggeration. Science, physics, data, and high quality legit upgrades play a huge role.

Every question on "German SUV for towing" cannot lead into "don't buy German SUV for towing".

Probably below people need to be a lot more careful about OEM specs than people like us who are actively asking right questions and making informed decisions (last one is an exception; I love what that guy is doing) -

https://www.terragalleria.com/images.../viet7696.jpeg

https://i1.trekearth.com/photos/40370/busride.jpg

https://media.gettyimages.com/photos...re-id453288203

https://www.youtube.com/watch?v=ZHk13Xa8dqI

[BayouBiker]

Originally Posted by knight-rider

I disagree. Your vehicle collects far more data than you can imagine. If you don't believe, then ask a Tesla engineer. They have built an empire on the data collected from customers. They have every possible data to tune the car, and to make the cars the safest vehicles on the planet. No wonder their stocks are going crazy. OEMs use field data all the time to tune the cars every year to make them safe and powerful. This has been happening since ages. That's why Porsche 911 turbo S is one of the finest machines on a race track, and Ford 350 is one of the sturdiest vehicles to haul tons of load. German SUVs don't bother to gather towing data much because they don't care. They are not targeting towing customers explicitly in US (at least for now). That's what Bono was hinting at.

I don't dispute OEM data gathering, but perhaps you misunderstood my point. Customers generally do not put themselves in situations that test the limits so the customer data doesn't speak to the edges of stability. Tesla insurance seems to be nearly double that of comparable vehicles, so I'm confused how safest on the planet comports with that reality. Maybe you're right but the crash data doesn't jibe well either. The inconsistencies are adding up.

How can we validate your claim that German SUV manufacturers don't care about towing data? What hard evidence supports that supposition, bono's hints notwithstanding.

Let me summarize. If you have a German car with tow capacity of 7500 lbs towing 7300 lbs trailer with below setup

• Reinforced hitch

• WD + suspension tuning to create no more than 0.5" delta between front and rear wheel wells

• axle loads below the specs

• Propride or Hensley hitch to eliminate sway

then you won't seen an oversteer at 70 mph BECAUSE of your setup. User error can cause oversteer (uneven load in trailer or no traction) and that could happen with any vehicle.

I'm not convinced this is true. My BMW X5 combined towing data for a 2018 model says otherwise. Perhaps you have more accurate confirmation? A round on a skidpad hitched up and the understeer gradient results would be good confirmation.

Furthermore I can walk you through the primary factors driving understeer gradient while towing. Set-up specifics (presuming it is installed well enough to function) is not a significant factor.

I don't understand how a German SUV weighing 5000 lbs and towing 7300 lbs trailer with rock solid setup like above can oversteer at 70 mph but a heavy duty vehicle weighing 7000 lbs and towing 14000 lbs trailer won't oversteer under the same circumstances.

And this inability to understand the dynamics of suspension, steering and handling systems of a towing combination and the feedback responses involved is the reason most people incorrectly assume that if the towing combination feels great on the road and handling performance is stellar, it must be stable. Unfortunately that is simply incorrect.

If you still don't believe, then please rent a German SUV with above setup (if you can find), and tow around at 70 mph, and you'll experience it first hand. I can confidently say there is no oversteer with above setup because I have tried above setup in PNW mountains during winter storm on I5 (rain + heavy cross winds). The only thing I was missing was Hensley/Propride hitch.

Fortunately I have the engineering training and experience along with industry data provided by acquaintances so I don't have to believe or take it on faith. I know. I also don't have to rent a German SUV, I can just hitch up my Wife's

Please check out all the videos in this link (all of them) -

Likely watched them all over the last 3 years.

Porsche holds a Guinness world record for towing Airbus A380. I'm sure A380 weighs more than 7300 lbs, and it's tongue weight exceeds OEM specs (617 lbs).

See it is examples like this that cause me to suspect you don't understand the concepts of towing stability. it's okay, very few people do.

I'm a safety freak. I don't want to share the personal reasons on why I care about it so much, because this is not the forum to share personal tragedies. But I research about safety before even considering anything else. Safety is complicated - external factors, vehicles' capability, and driver's common sense, all play into it. Making a blanket statement that German cars are unsafe because they are cutting close to OEMs specs is an exaggeration. Science, physics, data, and high quality legit upgrades play a huge role.

I don't doubt your sincerity, it is a personal safety event that drives me also. I don't generally make blanket statements. This thread is about X5's my statements involve the X5. German cars are like any cars, if you overload them with a trailer with excessive inertial moments, the combination will be unstable.

I am intimately familiar with the science, physics, and the data, I can quite accurately predict when many combinations will be unstable and I can speak to the impacts of upgrades as well.

Every question on "German SUV for towing" cannot lead into "don't buy German SUV for towing".

True that. When they are not overloaded, they make excellent tow combinations. I would use one if I didn't haul so much gear and my trailer was 2 feet smaller.

Probably below people need to be a lot more careful about OEM specs than people like us who are actively asking right questions and making informed decisions (last one is an exception; I love what that guy is doing) -

Guilt by association is a logical fallacy. As I mentioned, I could go hitch up my wife's SUV and head to the shopping center late tonight to test it for oversteer except I don't have to because I know the outcome already.

[knight-rider]

Originally Posted by BayouBiker

I'm not convinced this is true. My BMW X5 combined towing data for a 2018 model says otherwise.

X5 increased their towing capacity on 2019 models to 7200 lbs.

I have been researching on German cars towing safety for more than a year. I'm not convinced with your logic because you are leaving one of the most crucial factors in these cars - their brain. I'm an Engineer as well, and I have extensively checked on the fine tuning these cars do, especially Porsche. I have read and re-read all their software improvements, and watched countless videos on how they do stability management (just search on PSM/PASM), and spoken with the technicians on air suspensions. So it's not as simple as "you are close to specs and you are doomed". These German cars have tons of software tuning under the hood to avoid understeering and oversteering, and the manufacturers publish the max axle load per wheel based on that testing.

So your biggest safety net is to stay within the axle limits AND ensure your suspension can handle the tongue weight AND stay within the towing limits published by OEM. That's precisely what I mentioned earlier.

The car works million times more hard than us to send precise torque to axles. When you load trailer, some cars change the torque curve. Some cars, such as RR Defender has electric sway controller to apply brakes on one of the trailer axles to avoid understeer/oversteer/sway. When you make a sharp turn, some of these cars literally lift axles with an electrically controlled unit to prevent the g-force effect on the frame, eliminating as much sway as possible inside the vehicle. These functionalities minimize sway on the frame as well. There are videos where they show how they measure this swaying inside the car with precise instruments. This is where all the $$ spent on German cars go, and why the cars are unreliable because so much is going on under the hood. So no, German cars are not like all cars. It's not just about the physics, understeer/oversteer gradient K value, or pure mechanics of suspension/stability. Only the engineers who tuned the software knows the details. You and I don't know. Not knowing all of this is why theoretical physics knowledge without practical experience would lead to misinterpretations.

Probably one day Andy might be able to share skidpad testing results along with understeer/oversteer gradient values for all his setup on German cars. But for now, I believe in staying within axle limits and towing limits, and reinforcing hitch if I upgrade, and trusting the engineers who built my car to keep me safe.
[/QUOTE]

[jcl]

My understanding is that BB's towing data for the BMW X5 is derived from his mathematical models.

He has intimated that he has industry connections, but has not provided data.

The biggest challenge in sorting this out is reconciling the theoretical model data with real world testing data.

The ongoing logical fallacy that is evident in BB's posts is an appeal to authority.

Some issues are easy to spot. BB noted that he would tow a 23 with his wife's X5, but not his 25. I would tow a 23 or a 27 with an X5, but not a 25, due to the potential for a heavy tongue weight because of the layout of the 25 wrt usual cargo placement in the FB model. Towing performance doesn't necessarily correlate well with just trailer length.

[BayouBiker]

Originally Posted by knight-rider

X5 increased their towing capacity on 2019 models to 7200 lbs.

But what is the corresponding tongue weight? Tongue weight is a good proxy for trailer moment of inertia which in turn is the primary driver of oversteer instability for towing combinations. A 7200 lb Airstream will need at least 925 lb of tongue weight to be inherently stable for sway at 65 mph. The X5 has a much lower tongue limit. The 3 seat model has 720 lb limit. Others are less. The X5 has oversteer issues towing US travel trailers beginning just a touch over 6000 lb.

I have been researching on German cars towing safety for more than a year. I'm not convinced with your logic because you are leaving one of the most crucial factors in these cars - their brain. I'm an Engineer as well, and I have extensively checked on the fine tuning these cars do, especially Porsche. I have read and re-read all their software improvements, and watched countless videos on how they do stability management (just search on PSM/PASM), and spoken with the technicians on air suspensions. So it's not as simple as "you are close to specs and you are doomed". These German cars have tons of software tuning under the hood to avoid understeering and oversteering, and the manufacturers publish the max axle load per wheel based on that testing.

I have spent many years designing, writing, tuning, improving control systems and software but software cannot fix systems that are inherently unstable. They cannot overcome basic physical rules and laws.

So your biggest safety net is to stay within the axle limits AND ensure your suspension can handle the tongue weight AND stay within the towing limits published by OEM. That's precisely what I mentioned earlier.

Great and for the BMW X5 the limit is 720 lb max tongue but generally 626 lb for most models. If X5 owners followed OEM guidance, I'd have no concern.

So no, German cars are not like all cars. It's not just about the physics, understeer/oversteer gradient K value, or pure mechanics of suspension/stability. Only the engineers who tuned the software knows the details. You and I don't know. Not knowing all of this is why theoretical physics knowledge without practical experience would lead to misinterpretations.

I have a very good understanding of the details of sway control programming. I know that it can limit prevent the driver from operating outside of the safe limits, but it cannot move the limits.

Probably one day Andy might be able to share skidpad testing results along with understeer/oversteer gradient values for all his setup on German cars. But for now, I believe in staying within axle limits and towing limits, and reinforcing hitch if I upgrade, and trusting the engineers who built my car to keep me safe.

It would be great for someone to actually measure understeer gradient on the combinations they set up that exceed OEM towing guidance. I have never seen this happen, and I am fairly sure I know why. If by trusting the engineers who built your car you mean not exceeding any of their towing guidance including tongue weight, and frontal area if given, then I have no issue. For and X5 that means staying below 720 lb and on many models, lower still.