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Old 06-03-2020, 09:35 AM   #61
jcl
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I am confused by absolute statements about an X5 as if the are all the same. There have been four generations of X5 over the last 21 years, as well as mid-cycle LCI updated versions which had changes to the build consist. There have been factory offerings of 17, 18, 19, 20, and 21 inch wheels of varying widths, with some staggered with larger tires on the rear. There have been steel spring and air suspension models which lower at speed. There have been active suspension versions with dynamic suspension features, including anti-roll. There have been M sport and full M versions which handle differently. And somehow they are all claimed to understeer at a predefined speed when towing.
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Old 06-03-2020, 09:45 AM   #62
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We have a 2020 X5 with 21" wheels, tow package Full air suspension, rear steering, M Sport. It's lightyears better than our previous gen X5 (2008). I agree with this statement.

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I am confused by absolute statements about an X5 as if the are all the same. There have been four generations of X5 over the last 21 years, as well as mid-cycle LCI updated versions which had changes to the build consist. There have been factory offerings of 17, 18, 19, 20, and 21 inch wheels of varying widths, with some staggered with larger tires on the rear. There have been steel spring and air suspension models which lower at speed. There have been active suspension versions with dynamic suspension features, including anti-roll. There have been M sport and full M versions which handle differently. And somehow they are all claimed to understeer at a predefined speed when towing.
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Old 06-03-2020, 09:47 AM   #63
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I also agree with this POV. I beginning to feel like a soulless man unable to take a firm position.

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What about reading your own posts where you are bragging about truck being capable of evasive maneuvers?



Yes, it is crazy to tow ABOVE 65 mph with a truck. Primitive suspension, high center of gravity, poor handling, poor brakes are some of the reasons I would mention. This is a very subjective number. I would say that in some cases, people should not tow more than 50 mph - trucks with lifted suspension, hitch not dialed in, towing 8k+ lbs toy hauler.



How would you even compare BMW X5 vs. Cayenne? There are so many variances within one model (different suspension, different wheels, etc.). Each of this component matters.

Let me guess. Your model?
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Old 06-03-2020, 10:05 AM   #64
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Originally Posted by jcl View Post
I am confused by absolute statements about an X5 as if the are all the same. There have been four generations of X5 over the last 21 years, as well as mid-cycle LCI updated versions which had changes to the build consist. There have been factory offerings of 17, 18, 19, 20, and 21 inch wheels of varying widths, with some staggered with larger tires on the rear. There have been steel spring and air suspension models which lower at speed. There have been active suspension versions with dynamic suspension features, including anti-roll. There have been M sport and full M versions which handle differently. And somehow they are all claimed to understeer at a predefined speed when towing.
Don't forget that almost every car in the US is designed to favor understeer beyond traction limits. It's safer to crash the front of the car than the side of back.
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Old 06-03-2020, 10:51 AM   #65
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jcl meant to say oversteer. The X5 models discussed in this thread and others have oversteer issues when towing trailers over 6800 lbs. Notice though, this tread does not address every model mentioned by jcl so his confusion is simply a diversion from the valid points being made; a red herring argument. Further, jcl offers just innuendo but no statement of fact about understeer gradient differences between various models when towing in the weight ranges under discussion; a second logical fail.

The tested 2017 X5 does experience oversteer in the SAE combined handling tests. The described difference as tuned by BMW don't change oversteer propensity while towing relatively heavy loads to a great extent. This is because each model is tuned for the specific configuration to have near optimal handling unburdened. Thus the physical reality is trailer yaw inertia dominates the minor differences described. The possible exception is active rear wheel steering. I don't have any instructive data to inform that situation.
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Old 06-03-2020, 10:52 AM   #66
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Don't forget that almost every car in the US is designed to favor understeer beyond traction limits. It's safer to crash the front of the car than the side of back.
Agree. But remember that the chassis is offered in versions that are designed for up to 175 mph. Even the six cylinder versions have a published 150 mph top speed. As long as the tire and axle limits aren’t exceeded, and there is reasonable front/rear tow vehicle weight distribution, I wouldn’t be concerned about oversteer at 65 mph.
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Old 06-03-2020, 11:09 AM   #67
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jcl meant to say oversteer.
Yes, I did. Thanks

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The X5 models discussed in this thread and others have oversteer issues when towing trailers over 6800 lbs. Notice though, this tread does not address every model mentioned by jcl...
BB meant to say thread.��

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...each model is tuned for the specific configuration to have near optimal handling unburdened.
Disagree. These models are designed for the best handling over the range of loadings expected by the design team, over the range of speeds the vehicle is capable of. We aren’t talking about overloading the chassis here with vertical loads, just about loading it up to design loads. Attaining something close to the 50:50 design weight distribution. And operating it at a fraction of the design speed, around 40%.

The claim that the vehicle is optimized for no load is patently false. See the technical service info. BMW requires the use of sandbags to simulate passengers and cargo loads even to align the wheels.

I can just imagine the advertising copy that would follow from your claim. “The ultimate driving machine, as long as you don’t put anything in it.”
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Old 06-03-2020, 12:13 PM   #68
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I suppose I should have said unburdened by a trailer.
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Old 06-03-2020, 07:05 PM   #69
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Here you go






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Any chance you can share what was done? Pictures?
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Old 06-04-2020, 06:27 AM   #70
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What about reading your own posts where you are bragging about truck being capable of evasive maneuvers?
All modern US made 3/4 ton trucks, when unmodified are inherently stable in handling with 1000 lb of cargo and 8000 lb of trailer. This is a demonstrable fact and the statement says nothing about how firm, crisp or comfortable they maneuver, simply that they will perform at 65+mph with no stability issues.

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Yes, it is crazy to tow ABOVE 65 mph with a truck. Primitive suspension, high center of gravity, poor handling, poor brakes are some of the reasons I would mention. This is a very subjective number.
Subjective features you don't care for are hardly a reason to slow down. Objectively, if the vehicle trailer combination is stable at 65+ mph and it is capable of accelerating and decelerating within safe parameters as are all stock trucks in the US market when towing within the manufacturers guidance, then there is no logical cause to slow down.

Conversely when one has to shore up the stock hitch, that is a clue the manufacturer does not intend the vehicle to pull the load being contemplated. When one exceeds maximum advised trailer loads for all tested vehicle models one can be fairly certain the vehicle failed one or more of the SAE tests. In the case of the X5, it has sway control stability issues and oversteer issues when towing trailers over about 6800 lbs at US highway speeds. These are objective reasons to slow down

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I would say that in some cases, people should not tow more than 50 mph - trucks with lifted suspension, hitch not dialed in, towing 8k+ lbs toy hauler.
Advice to slow down when vehicles are modified or set up in ways that negatively impact handling stability applies to all makes and models. No reason to single out trucks.

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How would you even compare BMW X5 vs. Cayenne? There are so many variances within one model (different suspension, different wheels, etc.). Each of this component matters.

Let me guess. Your model?
The variations you speak of have minimal impact on towing stability because with large trailers, yaw inertia dominates and the manufacturers don't alter the basic characteristics to a large degree with these variations. The easiest way to compare tow capability of dissimilar vehicles is to follow the manufacturer guidance. I get that some people arrogantly believe they know more than the combined expertise of the manufacturer's experts. I've often heard, you can't fix stupid.
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Old 06-04-2020, 07:13 AM   #71
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Conversely when one has to shore up the stock hitch, that is a clue the manufacturer does not intend the vehicle to pull the load being contemplated.
It is actually more indicative of either the manufacturer utilizing a receiver design not built to handle WD equipment (like many European vehicles) or the manufacturer using a lower class of hitch receiver because they don’t see including a more expensive and higher class receiver as a market differentiator. They cater to the masses.

You know that experts reinforce hitches on US pickup trucks as well, right?
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Old 06-04-2020, 07:29 AM   #72
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Subjective features you don't care for are hardly a reason to slow down.
Actually, poor handling suspensions, poor brakes, and high centres of gravity are widely understood to be good reasons to slow down, in comparison to the speeds that can be safely managed by vehicles not including those “features” (as you call them).
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Old 06-04-2020, 07:52 AM   #73
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There are of course exceptions to every general rule. A review of the US market towing and hauling database indicates it is far more common (north of 88% in a cursory search) for hitch capacity to be well matched to vehicle capability. Higher if one adds comfort and ride quality measures. Many light weight vehicles have suspensions that are under damped for heavier loads so they are more comfortable when not towing. You often find lighter hitches on these vehicles likely to match a level of perceived passenger comfort.
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Old 06-04-2020, 08:11 AM   #74
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Actually, poor handling suspensions, poor brakes, and high centres of gravity are widely understood to be good reasons to slow down, in comparison to the speeds that can be safely managed by vehicles not including those “features” (as you call them).
It's not that simple. If a vehicle with those subjective features passes the handling and hauling tests, are stable at 65mph and can safely accelerate or decelerate to avoid obstacles, there is no logical reason to slow down. Conversely, a vehicle without these features but with low mass, short wheelbase, and tuned suspension consequently is unable to manage trailer yaw inertia, it must slow down to maintain stability so your statement is incorrect.

The correct statement would be that regardless of a vehicle's basic characteristics, if the set-up while towing is stable and capable as indicated by manufactures guidance as tested using US industry standards for US road speeds, there is no technical reason to drive slower than posted speeds.
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Old 06-04-2020, 08:39 AM   #75
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Technically, posted speed limits often don't apply to trucks or passenger vehicles towing trailers for most states. For instance, Texas limits speed for towing to 70MPH and is rarely posted. Each states DOT has their own codes and more often than not are arbitrary.

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It's not that simple. If a vehicle with those subjective features passes the handling and hauling tests, are stable at 65mph and can safely accelerate or decelerate to avoid obstacles, there is no logical reason to slow down. Conversely, a vehicle without these features but with low mass, short wheelbase, and tuned suspension consequently is unable to manage trailer yaw inertia, it must slow down to maintain stability so your statement is incorrect.

The correct statement would be that regardless of a vehicle's basic characteristics, if the set-up while towing is stable and capable as indicated by manufactures guidance as tested using US industry standards for US road speeds, there is no technical reason to drive slower than posted speeds.
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Old 06-04-2020, 09:55 AM   #76
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The correct statement would be that regardless of a vehicle's basic characteristics, if the set-up while towing is stable and capable as indicated by manufactures guidance as tested using US industry standards for US road speeds, there is no technical reason to drive slower than posted speeds.
I think it is very dangerous to suggest that something will be safe simply because of a published rating that follows published test standards. SAE doesn’t describe how to set up a tow vehicle. What they do is describe a set of test standards so that one can compare two different vehicles using the same baseline. As long as you are towing the same type of trailer under the same conditions that they use for testing, then their settings may certainly be used as a starting point. Recall that SAE doesn’t consider things such as trailer braking, or wind, etc, so it may be a challenge to always tow in those limited conditions.

I had understood from your previous posts that you had reviewed articles by CanAm on hitch setup. Here, you continue to disagree with the concepts they promote for setting up a tow vehicle.

That includes using insufficient WD settings, failing to consider the angle of the hitch head, and placing full faith in SAE tow standards that fail to address a range of real world issues.

I would be interested in your thoughts on the attached article, as it includes test track results on how to reduce oversteer on a 1/2 ton pickup, by not following the standards you promote above.

https://www.canamrv.ca/blog/post/hit...sion-bars-441/
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Old 06-04-2020, 10:55 AM   #77
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The SAE test standards represent a reasonable representation of the range of actual driving experience so they turn out to be an excellent predictor of actual experience. As you say, they don't cover every situation but it's quite unlikely a vehicle that easily passes the combined handling test will not manage trailer yaw in crosswinds for example. It's difficult in short posts to address all the limitations of SAE and manufacturer guidance, but as a general rule they make an excellent starting point and for many people here looking for advice, that is about as much information they are willing to entertain.

The SAE scope addresses manufacturer controlled variables and does not address owner responsibilities. There are volumes of information about proper set-up. Likewise, these threads are about vehicle choice and vehicle capability so it is proper to post here stipulating that the set-up is optimal or at least consistent and this would include trailer brake performance, and industry guidance on tow vehicle set-up so I don't often mention it. Not sure where you think I disagree with sound set-up guidance. I don't think I have advocated insufficient WD settings and again I have not seen nor participated in a thread about the details of proper and optimal set-up so complaining about failing to address it when it is not the topic seems a bit pedantic.

I'll take another look at the article and comment in a new thread.
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Old 06-04-2020, 11:48 AM   #78
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If you hitch up a trailer to M1 Abrams, it will be also stable. Safety on the road is not only about how a vehicle handles going straight, but also what are the capabilities of making emergency maneuvers. Putting stiffer shocks and springs into a primitive (by design) truck suspension, won’t make a vehicle safe and handling well.

I am still stunned how precise you are with your calculations regarding towing capacity of X5 (6,800 lbs) and how dismissive you are about things like wheels size, suspension types, etc. First, X5 which is discussed, has a towing capacity of 7,700 lbs. BMW chose to use different hitch in the US market and this is not the first time they chose to do. Second, I have two sets of wheels for summer and winter (18 vs. 20 inches – obviously different profiles). I can definitely feel the difference how the car handles towing or solo between both sets. If you add to this different settings of the suspension, you will definitely end up with different characteristics of handling (again, towing or solo). However, your model shows 6,800 lbs. No more questions.


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Originally Posted by BayouBiker View Post
All modern US made 3/4 ton trucks, when unmodified are inherently stable in handling with 1000 lb of cargo and 8000 lb of trailer. This is a demonstrable fact and the statement says nothing about how firm, crisp or comfortable they maneuver, simply that they will perform at 65+mph with no stability issues.

Subjective features you don't care for are hardly a reason to slow down. Objectively, if the vehicle trailer combination is stable at 65+ mph and it is capable of accelerating and decelerating within safe parameters as are all stock trucks in the US market when towing within the manufacturers guidance, then there is no logical cause to slow down.

Conversely when one has to shore up the stock hitch, that is a clue the manufacturer does not intend the vehicle to pull the load being contemplated. When one exceeds maximum advised trailer loads for all tested vehicle models one can be fairly certain the vehicle failed one or more of the SAE tests. In the case of the X5, it has sway control stability issues and oversteer issues when towing trailers over about 6800 lbs at US highway speeds. These are objective reasons to slow down

Advice to slow down when vehicles are modified or set up in ways that negatively impact handling stability applies to all makes and models. No reason to single out trucks.

The variations you speak of have minimal impact on towing stability because with large trailers, yaw inertia dominates and the manufacturers don't alter the basic characteristics to a large degree with these variations. The easiest way to compare tow capability of dissimilar vehicles is to follow the manufacturer guidance. I get that some people arrogantly believe they know more than the combined expertise of the manufacturer's experts. I've often heard, you can't fix stupid.
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Old 06-04-2020, 12:16 PM   #79
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I am still stunned how precise you are with your calculations regarding towing capacity of X5 (6,800 lbs) and how dismissive you are about things like wheels size, suspension types, etc. First, X5 which is discussed, has a towing capacity of 7,700 lbs. BMW chose to use different hitch in the US market and this is not the first time they chose to do.
As far as I know the X5 has never had a tow rating of 7700 lb for the US market. In the European market, lower speed limits, lack of industry standards, reduced corporate liability and strict licensing regulations provides a sound basis to select 7700 as a towing limit in the EU. I have repeatedly acknowledged the X5 can safely tow more if one slows down from the common 65 mph US speed limit.


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Second, I have two sets of wheels for summer and winter (18 vs. 20 inches – obviously different profiles). I can definitely feel the difference how the car handles towing or solo between both sets. If you add to this different settings of the suspension, you will definitely end up with different characteristics of handling (again, towing or solo). However, your model shows 6,800 lbs. No more questions.
Wheel size, reasonable tire choices, shocks, springs, sway bar tensions, alignment, suspension geometry, etc. will make small differences in towing capacity at 65 mph. Not worth mentioning.
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Old 06-04-2020, 12:51 PM   #80
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As far as I know the X5 has never had a tow rating of 7700 lb for the US market. In the European market, lower speed limits, lack of industry standards, reduced corporate liability and strict licensing regulations provides a sound basis to select 7700 as a towing limit in the EU. I have repeatedly acknowledged the X5 can safely tow more if one slows down from the common 65 mph US speed limit.
The X5 was only offered by the manufacturer with a reduced capacity receiver in the US, although this varies slightly by model. My X5 had no tow rating in the technical docs, owners manual, or door jamb label. The only tow rating came on the dealer supplied hitch kit. Current models differ. The point remains, though, that hitch ratings are not the same as vehicle ratings.

I think Euro industry standards are higher for towing. I know that my X5 met mandatory TUV standards years before the optional SAE standards were rolled out. TUV offers a 100 km/hr certification now, as an alternative to the 80 km/hr certification. You get a label for your registration. And that is without WD or electric brakes. 100 km/hr is pretty close to the 65 mph figure quoted.

I agree with you on the propensity of people to sue in the US. It seems to have set things back quite a bit, and driven behaviours that are based more on litigation, not best practices.
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