Porsche Cayenne, VW Touareg, Audi Q7 owners

[BayouBiker]

Originally Posted by mojo

The towing capacity for Cayennes, Touaregs. and Q7s is 7,700lbs.
In Europe, they do not allow WD hitches and their hitch rating is configured at 8% which equals 616lbs. In the US you can use a WD hitch and the hitch rating is 10% which is 770lbs. The main issue is payload. The OEM hitches are substantial, but if you wish to exceed the hitch weight, some suggest reinforcing the hitch. Main thing to look at is the payload and axle ratings. You can exceed the limits easily with anything larger than a 23' AS and a loaded trunk.

I towed for several years with a Touareg V8 and a V10 Diesel. As I increased in trailer sizes, had to eventually upgrade to trucks for increased payloads. I will not argue about handling, that all depends on the capabilities of the guy behind the wheel.

Interesting hypothesis, but 8% is an arbitrary number as described. European caravans are internally configured to be stable for tongue weights between 5% and 10%. (US travel trailers are much more substantial and require 10-15% tongue weights to remain stable over 55 mph). The Engineers chose 616 for some model years for towing combination oversteer stability considerations. In other years with slightly different configurations, the guidance was up to 770 lb. I do agree with your comments on axle limits, payload considerations, and hitch strength, though they do tend to have excessive flex in pitch which degrades WD performance.

[mojo]

Not an hypothesis, factual information direct from VW. They actually sent me a printed sticker for my receiver with the 7700 tow rating and 770 hitch weight. Also confirmed the acceptable use of WD hitches in US.

[gator.bigfoot]

It's simple mathematics based on European law. That's what it is based on.

[BayouBiker]

Originally Posted by mojo

Not an hypothesis, factual information direct from VW. They actually sent me a printed sticker for my receiver with the 7700 tow rating and 770 hitch weight. Also confirmed the acceptable use of WD hitches in US.

I don't see how a 770 lb limit on a sticker explains the basis for the 616 guidance. I do understand how they arrive at 7700 lbs based on licensing requirements in Europe, but as far as I know, the license restrictions are silent about tongue weight.

[Garfish]

Originally Posted by Ann83

Getting 19CB Caravel (empty weight 3600 lbs. max weight 5000 lbs) in May. Sway bar coming installed w Airstream.

Currently planning on towing w 2016 Toyota Highlander V6 (will tow 5000 lbs) w a brake controller to be installed. It also has Standard mode for shifting.

Would appreciate your input on whether the Toyota should fit the bill for uphills & steep declines.

We’re excited to hit the road out west!

Thank you!

Towed 22 Sport with Highlander and was fine. Steep mountain passes you go slowe, but what’s the rush?

[AlbertF]

I've been following this for some time now, and processing all of this information in my head. I needed to understand this better, so I went looking for the source, signed up for a free account, and read the report from 1980. It is entitled “Development of Maximum Allowable Hitch Load Boundaries for Trailer Towing”, and written by Richard H. Klein and Henry T. Szostak of Systems Technology, Inc. of Hawthorne, California. It was prepared for NHTSA.

https://www.jstor.org/stable/44632471?seq=1

The basic premise of the study, as I understand it (and I haven't spent hours reading and digesting all of the data), is that a combination should be able to handle a 0.3g turn without the tow vehicle breaking into oversteer. This was based on an assumption, derived from previous testing, that few drivers would throw a vehicle into a more than 0.35g turn and they would be more conservative with a trailer attached.

The study involved a series of three different cars (a subcompact, compact, and intermediate) towing eight different trailers. Loaded car weights were 3400, 4100 and 4750 lbs. The trailers were of various types, and ranged from 1500 to 6000 lbs. Brands and models are not specified.

The researchers experimented with different hitch weights (starting with 10% and going up from there) and different degrees of weight distribution. From a cursory scan of the data, if tongue weight was kept to at least 10% and the trailer was lighter than the car’s weight loaded, the 0.3g standard seemed to be reached quite readily.

I think the study is valid and reasonable, insofar as it goes. However, there are unanswered questions. For example, we don’t know from the paper is whether the receivers were reinforced to eliminate flex and how the WDHs were assembled and adjusted. In particular, were the ball mounts vertical or tilted forward, and was overhang significant or minimized. Further we have no idea what cars were used, and factors such as wheelbase and rear overhang were not addressed. On top of that, we know from experience that 1970s cars tended to understeer heavily, had imprecise steering, poor shock absorber control, etc. They might have been effective in avoiding oversteer, but that doesn’t mean that they were safe. I would also say they were harder to catch once they started sliding.

From this work, the testing regime should be very simple. Lay out a skidpad on a large parking lot, and drive a given combination around the circle. If it achieves 0.3g lateral acceleration without the rear tires of the tow vehicle breaking loose, it meets the standard. You don’t even need a g-meter, just a stopwatch, knowledge of the circle’s diameter, and a formula that you can Google.

In effect, Andrew T has already done this. He describes a 34’ Airstream drifting on 6 tires while the half ton pickup stayed planted – precisely the kind of situation that should have led to oversteer and rollover. This indicates that the Airstream did not and could not push the truck into an oversteer condition – the trailer tires broke free first. This was an older GM half-ton – relatively light by current standards, and the trailer was probably a ton heavier than the truck. And knowing Andy, there was a good chance that the 34’ had 65 series P-metric Michelins under it, more sticky than ST or LT tires.

There are numerous factors which are likely to influence the result, including trailer weight, tongue weight, length, trailer centre of gravity, hitch setup, hitch overhang, tow vehicle weight, tow vehicle wheelbase, tow vehicle centre of gravity, tow vehicle suspension design, shock absorbers, tires, and tire pressure. I suspect (but cannot prove) that most of Can Am’s combinations are capable of considerably more than 0.3g.

Another question – if a tow vehicle transitions into oversteer, how hard is it to catch? I certainly understand the conservative assumption behind setting up cars to understeer. They will not spin easily, and lifting off the accelerator will tend to correct any slide that occurs. However, is the risk of oversteer with a trailer any greater than driving (solo) on snow or ice? Being able to control a sliding car on snow is fundamental to safe winter driving; how does a drifting car and trailer combination compare? In 30,000 miles of towing, I’ve never had the occasion to find out, but I’d appreciate input from someone who has experienced it and was able to recover the slide.

Another issue: Brian has maintained that the engineers test tow vehicles to arrive at the tow ratings. I'm not sure that applies in all cases, particularly for cars. For example, why are E-Class sedans "not recommended" for towing in North America, but rated for 2100 kg in Europe? Marketing and profit margins are relevant for the manufacturers, and concerns about warranty repairs and the financial cost of liability are as well.

In the end, it comes down to an analysis that each person must make. I prefer to avoid the costs of a pickup (and they are all expensive when you take a hard look at life cycle costs). Instead, I’ll take a high degree of straight line stability (as opposed to cornering stability) of a combination that effectively resists bow waves and cross winds and minimizes the possibility of getting into a sway situation in the first place over an unsettled combination that will allow a (theoretically) harder turn before the rear tires break loose.

[jcl]

Originally Posted by BayouBiker

I don't see how a 770 lb limit on a sticker explains the basis for the 616 guidance. I do understand how they arrive at 7700 lbs based on licensing requirements in Europe, but as far as I know, the license restrictions are silent about tongue weight.

Exceeding 3500 kg (7700 lbs) results in higher vehicle and driver licensing fees in some Euro jurisdictions, and so is commonly used as a convenient classification for tow ratings. The manufacturers may test to that figure, and then publish it, but it doesn't necessarily represent the maximum vehicle capability, it is just a convenient cutoff point. For at least one model, BMW had a no cost factory order option in Europe for a higher tow rating for the X5. It was a label, by all accounts, and added around 500 kg to the tow rating. It may have resulted in higher vehicle licensing costs for owners, and potentially the maintaining of driver log books, but for some obviously that wasn't a concern.

Owner's manuals in Europe routinely refer to 5-8% tongue weight targets. The 616 lb tongue weight limit was simply that 8%. Other publications for the same vehicles referenced 10%, or 770 lbs. Volkswagen famously provided additional confirmation of the acceptability of WD hitches with at least some of their models, despite having previously listed not supporting the use of WD hitches. It looks like what they meant was they didn't test with it, and so couldn't provide recommendations on settings, but they didn't ban it. They simply didn't know about WD equipment in Europe where the engineers worked, and where the manuals were written.

When asked, VW mailed owners of some hitches labelled with 616 lb tongue weight stickers new stickers to apply, stating 770 lbs. It all looked like the tongue weight limits were very arbitrary, certainly not based on combination performance testing as some have suggested.

It is interesting to note that for the manufacturers of Euro SUVs that changed their documentation to "permit" or in other words, not ban, WD hitches, they didn't change the tow ratings. BMW had said a limit was x towing on the ball, and it was the same with WD equipment. This can be contrasted with a vehicle like the F150, which has a maximum tow rating of 5000 lbs on the ball, and often higher with WD equipment properly set up. The physics are the same on both sides of the Atlantic, so the Euro maximum tow ratings are not consistently determined with those in countries where WD equipment is commonly understood to improve combination towing safety.

None of this changes the fact that one shouldn't exceed rear axle and tire weight ratings. Those are real maximums.

[Tom_T]

Kurt -

I just see that you're also a PGHer, so probably are still in shock after the last few weeks of Steelers performance - or lack thereof! Especially this last one - 500 yds, 37 points, but 5 giveaways!

Back to the subject at hand - I've inserted my answers in bold into your text below:

"1. With respect to the trailer tow mode on these vehicles, is it engaged when a tow bar is engaged, or when the trailer electrical is engaged (assuming both receiver and 7-wire are factory, of course)?

Yes - tow mode for C/T/Q/etc. is engaged with the towbar, via a sensor/switch inside the receiver I believe. This triggers the tow mode in the VW/Porsche/Audi vehicles (& I think for BMW & MBZ too), which sets all systems into tow mode - much like pushing the tow mode button on the dash or column shift lever of some pickups & SUVs. That changes the vehicle systems' ECUs to run in the different controls' "mapping" for towing for the suspension & body control, transmission & transfer case & their shift points/etc., braking & engages the TV anti-sway system (it is opposite braking, as noted by another poster), and for engine performance & shift points, etc.

They only provide a pigtail & connector for any standard domestic 7-pin electrical connector (dealers sell Curt etc. electrical connectors, but you can also wire-in their 4 + 7 pin combo models too), but in Europe/UK the dealers sell a "Porsche" labeled round-7-pin as used over there. The electrical connector trigger the ECUs for the lighting system, and supplies power to the trailer, pretty much like the other TVs.
.

2. I realize that you mentioned that each of these vehicles has different tweaks, but does anyone know generally what changes in tow mode? I'd assumed shift points for the trans and I'd heard that the power tailgate is disengaged. From your post it looks like there's some anti-sway as well. Anything else?

The "tweaks" by maker 77 model have more to do with whether they are "tuned" as sport vehicles (Porsche), luxury (Audi), or in between (VW) - which has more to do with how P/V/A chooses to market each make & model or sub-model, as well as in the way that they do for each - such as for the base Cayenne, former TDI diesel, Hybrid/e-Hybrid, S, GTS, Turbo, Turbo S, etc. sub-models fo the Cayenne - along with each having differing optional suspension, powertrain, braking, etc. set-ups and options.

Yes - the complete suite of vehicle performance mapping is changed - as noted above. As far as I know all built in anti-sway systems on TVs are opposite braking, although some TVs with more advanced controlled suspensions can also adjust the stiffness/resistance at each corner of the TV, while opposite braking.

The Cayenne's PASM system for example does this in a similar way to it's performance driving mode to resist body sway in cornering. It's also interesting to note that Porsche's Cayenne & its PASM etc. systems were instrumental in taming the rear engine "tail dragger" 911 line's notorious tendency to kick its tail out in hard corners (oversteer) - resulting in the now very easy to drive and look proficient 996, 991 & 992 versions of late.

Yes on the opposite braking anti sway noted above, but I recommend still using a good WD/AS hitch with these vehicles, and they also reduce your driver workload & fatigue by making towing more stable - in addition to safer.
.

3. Is the Hensley cub considered a WD hitch?

Yes plus Anti Sway - or more correctly Sway Elimination hitch. Hensley makes 2 versions: Cub up to 6000 lb trailer & 600 lb HW, and Arrow up to 10,000 lb GTW & 1,000 lb HW, plus ProPride is a Hensley development of the Arrow's rating.

In addition to providing weight distribution, they are all "Pivot Point Projection" hitches which by the active geometry effectively "projects" the pivot point as if it's up under the TV near the rear axle & turns tighter more like a 5th wheel trailer - as well as that 2-parallel pivot arms hitch head assembly preventing sway from occurring at all - with the trailer only able to shift side-to-side without turning.

You can get the full story here:
https://hensleymfg.com/product/hensl...trailer-hitch/

The Cub runs in the mid to high $1,000s, which the Arrow & ProPride are in the $2,000s - and although pricey - they are absolutely steadfast for AS & arguably the safest WD/AS hitches out there, have infinite and easy screw-jack adjustments for tension (rather than lifting chains by link), the entire unit stays on the trailer A-frame with only the "stinger" towbar to remove when parked (stinger because its a 2" square tube/bar at both ends, with the coupler/ball at the head full time when mounted), their easy & low workload to drive, with a tighter turning radius, and the hitch head adds about 12" to the A-frame length, such that usually most rear hatches & tailgates can be opened when hitched.

IMHO they're cheap insurance and far easier towing - relative to pulling a $60-100K+ Airstream etc. or even the less expensive TTs, and especially with a $60-100K++ C/T/Q/etc. tow vehicle - which saves jackknifing &/or rolling a $100-200+/- rig!

Folks on here not using them complain about the cost, but my PGH Elders would say "Y'uns are penny wise & pound foolish"!

Thanks,
Kurt"

Cheers!
Tom
///////

[Tom_T]

Originally Posted by AlbertF

I've been following this for some time now, and processing all of this information in my head. I needed to understand this better, so I went looking for the source, signed up for a free account, and read the report from 1980. It is entitled “Development of Maximum Allowable Hitch Load Boundaries for Trailer Towing”, and written by Richard H. Klein and Henry T. Szostak of Systems Technology, Inc. of Hawthorne, California. It was prepared for NHTSA.

https://www.jstor.org/stable/44632471?seq=1

The basic premise of the study, as I understand it (and I haven't spent hours reading and digesting all of the data), is that a combination should be able to handle a 0.3g turn without the tow vehicle breaking into oversteer. This was based on an assumption, derived from previous testing, that few drivers would throw a vehicle into a more than 0.35g turn and they would be more conservative with a trailer attached.

The study involved a series of three different cars (a subcompact, compact, and intermediate) towing eight different trailers. Loaded car weights were 3400, 4100 and 4750 lbs. The trailers were of various types, and ranged from 1500 to 6000 lbs. Brands and models are not specified.

The researchers experimented with different hitch weights (starting with 10% and going up from there) and different degrees of weight distribution. From a cursory scan of the data, if tongue weight was kept to at least 10% and the trailer was lighter than the car’s weight loaded, the 0.3g standard seemed to be reached quite readily.

I think the study is valid and reasonable, insofar as it goes. However, there are unanswered questions. For example, we don’t know from the paper is whether the receivers were reinforced to eliminate flex and how the WDHs were assembled and adjusted. In particular, were the ball mounts vertical or tilted forward, and was overhang significant or minimized. Further we have no idea what cars were used, and factors such as wheelbase and rear overhang were not addressed. On top of that, we know from experience that 1970s cars tended to understeer heavily, had imprecise steering, poor shock absorber control, etc. They might have been effective in avoiding oversteer, but that doesn’t mean that they were safe. I would also say they were harder to catch once they started sliding.

From this work, the testing regime should be very simple. Lay out a skidpad on a large parking lot, and drive a given combination around the circle. If it achieves 0.3g lateral acceleration without the rear tires of the tow vehicle breaking loose, it meets the standard. You don’t even need a g-meter, just a stopwatch, knowledge of the circle’s diameter, and a formula that you can Google.

In effect, Andrew T has already done this. He describes a 34’ Airstream drifting on 6 tires while the half ton pickup stayed planted – precisely the kind of situation that should have led to oversteer and rollover. This indicates that the Airstream did not and could not push the truck into an oversteer condition – the trailer tires broke free first. This was an older GM half-ton – relatively light by current standards, and the trailer was probably a ton heavier than the truck. And knowing Andy, there was a good chance that the 34’ had 65 series P-metric Michelins under it, more sticky than ST or LT tires.

There are numerous factors which are likely to influence the result, including trailer weight, tongue weight, length, trailer centre of gravity, hitch setup, hitch overhang, tow vehicle weight, tow vehicle wheelbase, tow vehicle centre of gravity, tow vehicle suspension design, shock absorbers, tires, and tire pressure. I suspect (but cannot prove) that most of Can Am’s combinations are capable of considerably more than 0.3g.

Another question – if a tow vehicle transitions into oversteer, how hard is it to catch? I certainly understand the conservative assumption behind setting up cars to understeer. They will not spin easily, and lifting off the accelerator will tend to correct any slide that occurs. However, is the risk of oversteer with a trailer any greater than driving (solo) on snow or ice? Being able to control a sliding car on snow is fundamental to safe winter driving; how does a drifting car and trailer combination compare? In 30,000 miles of towing, I’ve never had the occasion to find out, but I’d appreciate input from someone who has experienced it and was able to recover the slide.

Another issue: Brian has maintained that the engineers test tow vehicles to arrive at the tow ratings. I'm not sure that applies in all cases, particularly for cars. For example, why are E-Class sedans "not recommended" for towing in North America, but rated for 2100 kg in Europe? Marketing and profit margins are relevant for the manufacturers, and concerns about warranty repairs and the financial cost of liability are as well.

In the end, it comes down to an analysis that each person must make. I prefer to avoid the costs of a pickup (and they are all expensive when you take a hard look at life cycle costs). Instead, I’ll take a high degree of straight line stability (as opposed to cornering stability) of a combination that effectively resists bow waves and cross winds and minimizes the possibility of getting into a sway situation in the first place over an unsettled combination that will allow a (theoretically) harder turn before the rear tires break loose.

That's a good study that I'd read a few years back trying to get up to speed on towing & TVs.

You gave a great summary and worth repeating in the quote, for those who don't like to look back in threads for prior posts.

Thanx!
Tom
///////

[Tom_T]

Originally Posted by jcl

Exceeding 3500 kg (7700 lbs) results in higher vehicle and driver licensing fees in some Euro jurisdictions, and so is commonly used as a convenient classification for tow ratings. The manufacturers may test to that figure, and then publish it, but it doesn't necessarily represent the maximum vehicle capability, it is just a convenient cutoff point. For at least one model, BMW had a no cost factory order option in Europe for a higher tow rating for the X5. It was a label, by all accounts, and added around 500 kg to the tow rating. It may have resulted in higher vehicle licensing costs for owners, and potentially the maintaining of driver log books, but for some obviously that wasn't a concern.

Owner's manuals in Europe routinely refer to 5-8% tongue weight targets. The 616 lb tongue weight limit was simply that 8%. Other publications for the same vehicles referenced 10%, or 770 lbs. Volkswagen famously provided additional confirmation of the acceptability of WD hitches with at least some of their models, despite having previously listed not supporting the use of WD hitches. It looks like what they meant was they didn't test with it, and so couldn't provide recommendations on settings, but they didn't ban it. They simply didn't know about WD equipment in Europe where the engineers worked, and where the manuals were written.

When asked, VW mailed owners of some hitches labelled with 616 lb tongue weight stickers new stickers to apply, stating 770 lbs. It all looked like the tongue weight limits were very arbitrary, certainly not based on combination performance testing as some have suggested.

It is interesting to note that for the manufacturers of Euro SUVs that changed their documentation to "permit" or in other words, not ban, WD hitches, they didn't change the tow ratings. BMW had said a limit was x towing on the ball, and it was the same with WD equipment. This can be contrasted with a vehicle like the F150, which has a maximum tow rating of 5000 lbs on the ball, and often higher with WD equipment properly set up. The physics are the same on both sides of the Atlantic, so the Euro maximum tow ratings are not consistently determined with those in countries where WD equipment is commonly understood to improve combination towing safety.

None of this changes the fact that one shouldn't exceed rear axle and tire weight ratings. Those are real maximums.

Great explanation for folks reading on this subject.

This explains why we're erroneously getting their Euro/UK 618 lb hitch receiver decals on some of our USA/Canada factory option & dealer supplied factory hitches. Since all of the C/T/A models are the same design and ratings USA/Canada & Euro-TUV/UK - you would think that they could come up with a common decal simply listing each rating both as such, and stop this confusion.

However, they do actually do tow testing with actual trailers over there - usually by the TUV standard (the German DOT & SAE), which is similar to our USA standard by SAE's J2807.

https://www.sae.org/standards/content/j2807_201602/

While not on various TT & TV combos - it does test and rate up to the tested limits (GTW, HW, GVWR, etc. weights) for various uphill & downhill braking & pulling capabilities.

The SAE standard also addresses WD hitches, so they're not actually "not banning WD" - but are listing 2 different GTW & HW ratings for no WD & with WD ("distributed"), as well as for with and without trailer braking (TUV does this distinction as well).

When VW/Porsche/Audi rate their SUVs for a Euro or USA/Canada towing capabilities and GTW/HW ratings (& I think BMW & MBZ, Land Rover, etc. too) - they are doing so based on both the TUV & SAE tests, and you can probably find them all/both with some research (I found the TUV ratings for the 1978-95 Porsche 928).

I'll also add that not only do they not know about WD hitches, but the UK & Euro countries have legally banned WD hitches since their popular availability here in the USA in the 1960's, in order to protect their home grown trailer/caravan makers from the the burgeoning big-bad USA trailer makers taking over.

So whenever you see a UK/Euro Airstream - it's actually built lighter for no WD, and narrower for their roads.

Part of the result of their WD ban, are those phallic looking "gooseneck" hitch/ball units that you see on UK/Euro cars & SUVs. Porsche makes a power folding closed & extend one for their Panamera and some other models which takes the phallic comparison to a whole new level!

Cheers!
Tom
///////

[Tom_T]

Originally Posted by BayouBiker

You're correct the chassis module has sway control (asymmetric braking) built into the programming and it can help with sway, particularly on straight roads, while cornering, it is less effective. Consider that the engineers are of course familiar with the vehicle's sway control programing but didn't raise the towing limits.

If performance tuned suspension and steering was a good quality to have for towing and hauling, then trucks would have performance tuning also. Unfortunately you can't have your cake and eat it too and you can't safely tow large loads with performance vehicles. They are susceptible to oversteer if you happen to let trailer yaw become excessive.

Brian -

I can't agree with your logic on this one.

The C/T/Q/etc. built in sway control includes both asymmetric braking and asymmetric suspension control which stiffens the resistance to body roll and yaw - thanks to their advanced performance suspension systems - which are in fact superior to trucks in the same class - e.g.: a Ford F150 with either the base 5,000 lb tow rating or the tow options for 6,000 or 7,500 lbs with each level's added equipment.

I've towed with all 3 plus much higher rated F250s & RAM 2500s and the Cayenne/Touareg/Q7 models, and their far better suspensions and much lower center of gravity make them much more stable tow vehicles than any of those trucks - and far easier to load/unload and access/egress the cabins, than the ludicrously jacked-up trucks of the past decade-plus.

If I want to haul a big load of lumber, bricks, cement, gravel/sand, etc. - then the truck is the better option (and preferably to rent when needed) - but its a royal PITA and causes too many injuries they way that the Big 3 and others have been arbitrarily and purposelessly over-jacking-up the current trucks. In our construction industry, there has been a steady rise in back & other injuries due to the high lifting in & out of jacked up truck beds since the mid-2000s when the marketing guru's decided to build all trucks for the 20% "Ricky Off-Road Racers" for the "Look" factor - and not for the practical haulers that they used to be.

Any tow vehicle is susceptible to oversteer under excessive yaw, ergo why anti-sway hitches &/or TV systems are important safety measures.

Trucks are single purpose TVs always for hauling freight/loads (towing) - whereas SUVs are multi-purpose for towing (hauling) as well as passenger and other road use (e.g.: sport driving for Cayennes, X5-8s, Q5-7, etc.).

However, if you want to classify 1/2 & 3/4 ton pickups as your definition of "trucks" above - then the latest versions of the RAM 1500 & 2500 do have adjusting performance suspensions - ergo their recent much improved ride and MT etc. Truck of the Year awards.

Also, VW & Mercedes do make "trucks" for other international markets with the same performance suspensions as their SUVs sold here - and VW has/had a crew cab pick-up based on their Touareg SUV in South American, Asian and other worldwide markets.

Performance tuned steering, suspension and braking are all excellent features to have in a tow vehicle for both safety, reducing driver fatigue and workload (also safety factors), and ease of use - as well as having a vehicle that doesn't require a ladder to get into or check the oil, etc.

Cheers!
Tom
///////

[Tom_T]

Originally Posted by mojo

The towing capacity for Cayennes, Touaregs. and Q7s is 7,700lbs.
In Europe, they do not allow WD hitches and their hitch rating is configured at 8% which equals 616lbs. In the US you can use a WD hitch and the hitch rating is 10% which is 770lbs. The main issue is payload. The OEM hitches are substantial, but if you wish to exceed the hitch weight, some suggest reinforcing the hitch. Main thing to look at is the payload and axle ratings. You can exceed the limits easily with anything larger than a 23' AS and a loaded trunk.

I towed for several years with a Touareg V8 and a V10 Diesel. As I increased in trailer sizes, had to eventually upgrade to trucks for increased payloads. I will not argue about handling, that all depends on the capabilities of the guy behind the wheel.

Thanx Mojo.

For the doubters on here - he is actually quite correct on these points, as I noted in my prior posts above.

Although the better handling vehicles are inherently better and safer for drivers of all skill levels, as I noted in my example above of Porsche applying the Cayenne's PASM to the 996-992 911 rear engine models to make them far more stable.

The same applies for the C/T/Q/etc. SUV/CUV TVs - as I'm sure you can attest between the enhanced suspension etc. of your monster V10 TDI - which model was in fact used the Le Mans/etc. Homologation vehicle for the Audi V10 TDI race cars - vs. of your more placid tuned Touareg V8.

BTW folks - Mojo's Touareg V10 TDI was the same model as featured in the Touareg vs. 3500 Duramax "Pull-off" U-tube that I posted last week!

I just noticed that you've moved down to Santa FE NM from CO!

Cheers!
Tom
///////

[Tom_T]

Originally Posted by Mr. Merk

We use the Tekonsha Prodigy for our "one trailer, multiple tow vehicles" solution. No wiring required. So easy.

Ditto for me - Tekonsha RF since 2013 & towing with many different rented TV since then.

Also - once you've "paired" the Tekonsha RF to a particular TV or several - it remembers the settings so you don't have to pair it each time, nor even with different vehicles of the same model. We've rented a few F150s, dozens of F250s & RAM 2500s, and several Nissan Pathfinders 2013-2018, but never had to re-pair the system after the first.

It's also an easy mount on the A-frame or front of the trailer, and the 7-pin plugs into the RF controller box, then its own 7-pin into the TV, then you plug the hand controller into the 12v/cigarette lighter outlet in the cabin, and keep it at hand to use the brake boost button - no reaching & searching for the on or under dash boost button of the under-dash mounted or built-in factory brake controllers on other vehicles.

Check around for when they're on sale at eTrailer, Camping World, at Tekonsha, etc. "to save a few bob"!

Good Luck!
Tom
///////

[Tom_T]

Originally Posted by mikextr

If you stick with your 2/3 of max rule of thumb, then there really is no need for weight distribution or sway control. I've been "freeballing" for years with my Cayenne and 67 Overlander, but I'm well within your 2/3 rule. Porsche says not to use WD so I will follow their guidelines. I have never had a problem with sway so I've never considered adding any type of sway control. My Cayenne is so rock solid, that the semi drivers have white knuckles on the steering wheel when they pass me because the air blast redirected back at them

If other folks want to tow heavier trailers and use WD to achieve their goals, I'm all for that. Personally, I think a Cayenne could handle a 34 footer with ease if set up correctly.

Hey Mike -

Correction:
Porsche does not ban WD use on Cayennes here in North American markets where WD hitches are legal. They're only banned in the UK & Euro markets.

The key for whether you need a WD hitch is if you are over or under the load bearing (non-WD) rating for the Cayenne (and any others), &/or if you want an Anti-Sway hitch for further safety.

As I noted in my reply post to Kurt from PGH above - Porsche does in fact rate the Cayenne & Macan for both "weight bearing" and "weight distributed" hitches with different HW and GTW ratings for each - with your "freeballing" rating lower (as well as lower for unbraked trailers).

VW, Audi, BMW, Mercedes, etc. also do so, as do their OEM hitch suppliers Westfalia Werke, Oris, etc.

So you may in fact be overloading your "weight bearing" rating of the hitch and Cayenne without a WD hitch - so you'd best check your `67 AS's wet & loaded weight vs. that rating.

However, most vintage trailers such as yours and our `60 Avion T20 are 50-60%+ lighter than the trailers of today - primarily due to the newer AS's substituting lighter & stronger Marine Plywood for heavy & cheaper Particle Board & OSB, less lightweight & more expensive steel for aluminum, etc.

So you may be within your Cayenne's "bare ball" tow ratings, but probably close.

That 2/3's of max rating would only apply if that actually is the non-WD rating, and the 7700 lb GTW rating is the same, but the HW drops to 616 without WD (770 HW with WD).

2/3's is just an arbitrary "personal comfort factor" of somebody - not any sort of "official" rule of thumb.

Andy T at CanAm and some other members on here have towed 28-30' ASs with the Cayenne, but I'm not sure about 34' - and that would depend on tow ratings vs. weight.

If you search back a few years ago in this thread, one of the Porsche Techs at a P-dealer actually posted a photo of the Cayenne tow rating with and without WD, with & without trailer brakes, HWs, etc. from his official factory Porsche Service Manual.

But for some reason every week or so another person comes on here and categorically but incorrectly states that you cannot use WD on the Cayenne, Touareg &/or Q7 etc. - unfortunately due to Porsche, VW & Audi having inconsistent owner manuals, hitch decals, etc. on the matter.

But in fact they've had the same USA/Canada ratings of 7716 lbs (rounded to 7700) GTW and 770 lbs HW since the start in the 2003 MY, and the same for the Touareg and Q7.

Blame VW/Porsche/Audi conglomerate for poor documentation, and most dealers & their techs for poor training on towing aspects.

So be at ease if you ever want to use a WD/AS hitch on your Cayenne.

Cheers!
Tom
///////

[BayouBiker]

Originally Posted by AlbertF

I've been following this for some time now, and processing all of this information in my head. I needed to understand this better, so I went looking for the source, signed up for a free account, and read the report from 1980. It is entitled “Development of Maximum Allowable Hitch Load Boundaries for Trailer Towing”, and written by Richard H. Klein and Henry T. Szostak of Systems Technology, Inc. of Hawthorne, California. It was prepared for NHTSA.

https://www.jstor.org/stable/44632471?seq=1

(snip...)


From this work, the testing regime should be very simple. Lay out a skidpad on a large parking lot, and drive a given combination around the circle. If it achieves 0.3g lateral acceleration without the rear tires of the tow vehicle breaking loose, it meets the standard. You don’t even need a g-meter, just a stopwatch, knowledge of the circle’s diameter, and a formula that you can Google.

In effect, Andrew T has already done this. He describes a 34’ Airstream drifting on 6 tires while the half ton pickup stayed planted – precisely the kind of situation that should have led to oversteer and rollover. This indicates that the Airstream did not and could not push the truck into an oversteer condition – the trailer tires broke free first. This was an older GM half-ton – relatively light by current standards, and the trailer was probably a ton heavier than the truck. And knowing Andy, there was a good chance that the 34’ had 65 series P-metric Michelins under it, more sticky than ST or LT tires.

There are numerous factors which are likely to influence the result, including trailer weight, tongue weight, length, trailer centre of gravity, hitch setup, hitch overhang, tow vehicle weight, tow vehicle wheelbase, tow vehicle centre of gravity, tow vehicle suspension design, shock absorbers, tires, and tire pressure. I suspect (but cannot prove) that most of Can Am’s combinations are capable of considerably more than 0.3g.

Another question – if a tow vehicle transitions into oversteer, how hard is it to catch? I certainly understand the conservative assumption behind setting up cars to understeer. They will not spin easily, and lifting off the accelerator will tend to correct any slide that occurs. However, is the risk of oversteer with a trailer any greater than driving (solo) on snow or ice? Being able to control a sliding car on snow is fundamental to safe winter driving; how does a drifting car and trailer combination compare? In 30,000 miles of towing, I’ve never had the occasion to find out, but I’d appreciate input from someone who has experienced it and was able to recover the slide.

Another issue: Brian has maintained that the engineers test tow vehicles to arrive at the tow ratings. I'm not sure that applies in all cases, particularly for cars. For example, why are E-Class sedans "not recommended" for towing in North America, but rated for 2100 kg in Europe? Marketing and profit margins are relevant for the manufacturers, and concerns about warranty repairs and the financial cost of liability are as well.

In the end, it comes down to an analysis that each person must make. I prefer to avoid the costs of a pickup (and they are all expensive when you take a hard look at life cycle costs). Instead, I’ll take a high degree of straight line stability (as opposed to cornering stability) of a combination that effectively resists bow waves and cross winds and minimizes the possibility of getting into a sway situation in the first place over an unsettled combination that will allow a (theoretically) harder turn before the rear tires break loose.

First to clear up a misconception, oversteer occurs long before the rear tires lose traction and start sliding. When cornering, sheer stress contorts the sidewalls and alters the tire footprint so the path the tire takes is not aligned with the wheel direction. The angular difference is the slip angle. If the rear tires have a higher slip angle than the front, the vehicle has oversteer. On the skid pad, a skilled driver can maintain the correct arc even with oversteer at .3 g and much greater and most modern vehicles towing under their limits are capable of .6 g and more before any of the tires loose traction. So in order to know if a combination has oversteer you have to carefully measure steering angle and vehicle yaw angle.

Likewise, in Andrew's maneuver, while it may look and sound impressive, it is not assurance the combination does not suffer from oversteer. By inducing drift in the trailer, lateral forces from the trailer normally acting on the vehicle were greatly reduced so though it is counterintuitive, the demonstration does not show stability against oversteer. In addition, a skilled driver can react and correct for the onset of oversteer before yaw angle exceeds the point of stability and thus mask the symptoms. Again this is why oversteer must be carefully measured.

Oversteer when towing is significantly more difficult to manage than with the vehicle alone because the lateral force imposed by the trailer multiplies with yaw angle so the combination will approach and pass both the window of stability and the critical points at accelerating rates while the vehicle alone will not. For most drivers, oversteer will get out of hand before they react. Again, all this happens long before the tires lose traction, and by the time they do, the combination is well past the critical point, well past the point the vehicle is able to respond correctly to driver input.

Performance vehicles are significantly more at risk for sway and oversteer because steering and suspension is tuned for cornering so the static understeer gradient is generally half of that of vehicles designed for towing to begin with. Add a trailer and the combination may well inherently oversteer if the trailer is large enough and the driver allows trailer yaw to exceed a narrow window. Include the dynamic effects, and it is guaranteed.

I see where some of the e-class vehicles with smaller motors and the 9 speed transmission are not recommended for towing. Most have tow ratings listed for the US in my sources.

I agree in the end it is a personal choice of how much risk one is willing to impose on themselves their passengers and those who share the road. It is also a choice of how much faith and trust one places on their driving skill to avoid going outside the narrow stability profile that exists for combinations with oversteer gradients.

From the looks of the videos, Andrew appears to be an expert driver quite able to avoid oversteer and sway instabilities in overloaded combinations. Many others who tow with overloaded combinations could as well, but it is unwise and irresponsible to suggest to others who's driving skills are unknown to do the same without fully disclosing the risk they are inheriting.

[Bier]

Did a search of this thread and only returned 1 mention of "SQ7" (not super surprised as it's only been available since MY2020).

Does anyone have any experience with the SQ7 vs. the Q7 and willing to share? I would imagine the extra hp and torque would be beneficial (plus fun when not towing) but curious of real world experience. Currently been debating between a Q7 or Cayenne S, but could see going for a SQ7 potentially too. Thanks for any info

[waninae39]

interesting posts

my spouse and i took BMW driver training a few years ago.
full day with THEIR cars.
The lead trainer puts $100 on the table and states that he will pay AYNONE who can damage or impair any vehicle ( i hear that MB and Porsche do similar training methods).

They want you to push the car as hard as it can go and not worry about it. The $100 is to keep you pushing. They also replaced the tire every 1-2 weeks
they also disable all electronic stability systems and antilock
they also have a 2 way radio in the car as the instructor watches from outside

They teach you braking, steering avoidance and recovery. The oversteer and under steer situations are done on a wet skid pad

What i learned was regardless of under or over steer, the recovery method was the same;
off the gas,
don't touch the brakes and
let the car slow down and recover.
on the wet skid pad you can feel the car skidding in both oversteer and under steer situations, then at some point BANG, it recovers, some times quite hard.
they made you do this multiple times so it gets drummed in.

the BMW driver training was Excellent
BTW, no one got the $100 as no car was damaged that day

[BayouBiker]

Just to reiterate, oversteer and understeer due to loss of tire traction resulting in lateral tire slide is a very different animal than oversteer due to varying cornering stiffness/ tire slip angle, where the tires remain firmly bonded to the road. The recovery is also different where you must quickly steer out of the corner so the front tires remain tracking with the rear tires and yaw angle does not increase. Respond too slowly while towing and the vehicle will lose control quickly.

[Tom_T]

Originally Posted by Bier

Did a search of this thread and only returned 1 mention of "SQ7" (not super surprised as it's only been available since MY2020).

Does anyone have any experience with the SQ7 vs. the Q7 and willing to share? I would imagine the extra hp and torque would be beneficial (plus fun when not towing) but curious of real world experience. Currently been debating between a Q7 or Cayenne S, but could see going for a SQ7 potentially too. Thanks for any info

Bier,

You can look back further in this topic for the Q7 4.0L non-turbo V8 in some of the older posts here, from when Audi still offered the non-turbo Q7 V8 for some real world V8 towing experience (I don't recall what years exactly, before they dropped their V8).

The SQ7 looks good on paper when I looked at them, and worthy of consideration if you need the 3rd row & 6-7 seats &/or extra cargo space over the CayS.

Another new 3 row & 6-7 seat more cargo option is the new since 2020 Lincoln Aviator with their 400 HP/425? TQ V6TT & it's eHybrid version - IF they get their new model manufacturing bugs fixed, and if it proves to be reliable (while similar to the Ford Explorer, that one only has the 400 HP V6 TT in their SHO off-road hot rod model, & without the niceties & features of the Lincoln).

https://www.lincoln.com/luxury-suvs/...coln%20aviator

I know that it's blasphemy for a Porsche, BMW & VW guy like me to suggest looking at a Lincoln - it is interesting, with similar capabilities to the Audi Q6/SQ6, and a nice looking vehicle (can't say about driving & towing without having tried one Yet). There are also other P/VW/A, BMW, MBZ, Land Rover, Jaguar, etc. options worth a look-see as well.

Another Audi option might be their A6 Allroad & RS6 Avant wagons - if they ever offer it's tow package here in the USA - since it has the same TT V8 (or more in the RS) - but they're traditional low center of gravity wagons.

https://www.audiusa.com/us/web/en/mo.../overview.html

https://www.audiusa.com/us/web/en/mo.../overview.html

The CayS is a V6 TT since 2015 MY with comparable HP/TQ to the prior non-turbo V8 CayS on paper, plus there are still TT V8's in the Cay Turbo/Turbo S & Turbo ES.

The 2019> Cay E-Hybrid V6 + E looks intriguing with more combined HP/TQ than the 2019> 2.9L & 2015-18 3.6L V6 TT CayS - so that's one to check out too, for both towing, around town unhitched, and exuberant driving - club or otherwise.

We'll check them all out further after this COVID thing is tamed, and we actually put a new TV/SUV to full use. It makes no sense for us to do so under current conditions.

Cheers!
Tom
///////

[Tom_T]

Originally Posted by waninae39

interesting posts

my spouse and i took BMW driver training a few years ago.
full day with THEIR cars.
The lead trainer puts $100 on the table and states that he will pay AYNONE who can damage or impair any vehicle ( i hear that MB and Porsche do similar training methods).

They want you to push the car as hard as it can go and not worry about it. The $100 is to keep you pushing. They also replaced the tire every 1-2 weeks
they also disable all electronic stability systems and antilock
they also have a 2 way radio in the car as the instructor watches from outside

They teach you braking, steering avoidance and recovery. The oversteer and under steer situations are done on a wet skid pad

What i learned was regardless of under or over steer, the recovery method was the same;
off the gas,
don't touch the brakes and
let the car slow down and recover.
on the wet skid pad you can feel the car skidding in both oversteer and under steer situations, then at some point BANG, it recovers, some times quite hard.
they made you do this multiple times so it gets drummed in.

the BMW driver training was Excellent
BTW, no one got the $100 as no car was damaged that day

I know that Porsche offers similar driver training & test drives at their "Porsche Experience Centers" in LA (Carson) & Atlanta - but cannot attest to the $100 offer.

I also know that BMW-CCA & PCA car clubs offer various "Driver's Ed" courses at the local club levels - where you get to train in your own car(s). That may be more what you & your spouse want to do with your own vehicle(s) that you drive every day - rather than the school's cars (there is a tech inspection for vehicle equipment/condition/maintenance beforehand).

However - I'm pretty sure that none of the clubs' nor manufacturers' courses offer anything on "steering" a car sliding backwards on wet pavement, around a freeway curve, in front of a panic braking Semi, with nearly bald tires, in order to get off the road - as I had to do back in 1971 while in college & too poor to get new tires, thinking it was okay to stretch getting new tires for my 1968 Opel Kadett through usually dry SoCal summers, until I saved enough from my extra 3rd summer job - when CalTrans left a set of broken sprinklers flowing across & down the banking blind turn of the I-10 east to I-5 south interchange (locals will know it) - and although I was off the gas & no brakes immediately - the Opel immediately flipped end-for-end backwards sliding still at close to 55 mph!

I'm still here - so I was successful, and the trucker and others who saw it and stopped to check on me were "entertained" and impressed by that young 18 year old driver's skills - and the trucker said something like: "Well they don't teach that in driver's ed, but you did well! ... and were very lucky! ... Now go get those d**m tires fixed!" - while I was just happy to get out of it alive, and I did get 4 new tires at Sears that day, and went without some meals/etc. for the rest of the month with the help of some overtime.

Maybe Porsche, BMW, MBZ, etc. should add that "maneuver" to their training courses.

Cheers!
Tom
////////