Towing with my 35D- load leveling?
 

On saturday I'm likely going to be towing about 5500lbs a bit over an hour away. I'm still super nervous, being that I don't have the self leveling suspension, and know it's going to be squatting like crazy with 500-600lbs on the hitch.

Everything I've looked into says that retrofitting the SLS is near impossible, because the car's not wired for it if it wasn't optioned for it. I can't really find anyone that seems to have fitted any aftermarket system either- Vague mentions of doing arnott bags, but with a standalone pump. I'm trying to find out if this would be possible. Can anyone point me any direction?

I'm going to do a nice suspension refresh sometime soon on the front, and would love to do the back too, but want to consider making the vehicle more tow worthy. It's got the rating for 6klbs, and I do plan on driving it some decent distance at around that weight. I've had 2300 lbs behind it before and it was great, barely noticeable.

You'll be fine. Make sure you know what your tongue load is, take it to a weigh scale to be sure.

I’ll have a tongue weight scale to check it before driving.

Two ideas:

(1) use a WD hitch setup
(2) there are generic Airbags and spring helpers people install on their pickups etc to prevent sag when towing. Perhaps they are avail in a size which could fit within your rear coil springs. You fill them up with an external air pump.

You'll be fine. Towing a 20' SeaRay (3500lbs dry + trailer and gear) I couldn't hardly tell it was behind me so SLS here.

For those who were unable to get the rear self leveling suspension yet want to tow bigger loads, maybe this could help:

https://www.amazon.com/LIFT-60732-10.../dp/B000CFS028

My rear end squats pretty hard with my car hauler behind me. Load is 5500ish, and I'm putting around 500lbs on the hitch. car handles fine, but I'd like to avoid the squat + the crazy tire wear that I'm sure will follow it. Have about 3k miles of towing planned for the near future, so I'd like to get the ride height settled.

Bfeng- That looks interesting. Reviews are mostly with various generation toyota siennas, but theres a highlander too. Looking at their site, I'm going to follow their directions for measuring my rear springs- min interior diameter in middle of spring, and height. If i find a set that roughly matches my measurements, I'm going to go for it. What's $100 for a try. I'll get a cheap DC compressor if the install goes well, so I can change it on the fly. I'll keep this thread updated with information I find!

I’m really disappointed with how the F15 handles hitch weight vs the e53, I would have thought it would be better, not worse!


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Bmw designs these for road worthiness, rather than hauling ability. Base on the user base, I completely understand it. Wish I had SLS though, and I'm really hoping that I find a set of bags that will fit and they can help me out!

If you plan to tow with an X5, you should stick with those equipped with the air suspension. When I was shopping I specifically only looked for diesel plus 3rd row seats to make sure I had the torque and air suspension. It took quite a bit longer to find the right one to buy, but the X5 works great without bandaids and compromises.

Trying to tow with significant tongue weights without air suspension or WD would be a problem with most vehicles, not just the X5. You can sag out the back of a pickup too.
For that matter I’m surprised pickups don’t come with an OEM rear air bag setup for ride height leveling. These aren’t cheap vehicles anymore.

I bought mine for a steal- $4300 for my 35D. After a delete and a wheel bearing, I'm around 7k deep in a wonderful SUV that's still rated to tow 6000. This deal came along and I couldn't pass it up, as much as I would've loved to have the leveling suspension. I'm going to make do, and try to improve my car's setup, becasue it's rock solid reliable, and I plan on driving it for the next 150-200k miles. At the rate I'm going, that'll be 4-5 years, so I'd like to tailor it to my needs a bit. Most of my tows are only 50-70 miles each way, depending on which track I go to, but I'm going to make 2-3 distance trips, one of them being about 1000 miles each way. The X5 handled fine at highway speeds, I'd trust it to do it perfectly fine how it sits now, but if there's a way to improve the squatting, I'll give it a shot!

At the end of the day, I do wish the random crazy good deal I got happened to have the SLS, but beggars can't be choosers!

Ok, since I always frown uopon posters that talk about trying something and never pull through.... I ordered a set. I measured my springs and found that the interior width is about 4.25" and the interior height is about 7.5" from perch to perch. Inputted into their "choose my set" forum at https://www.airliftcompany.com/works...ir-spring-kit/ and it came out with 60909, 8"long, 4" wide. They say its better to undersize the width a big than oversize, and emphasize that it will cause premature failure to oversize the width. There's a chance I should've gotten the 7" but their site said go with 8, and they have a lifetime guarantee on the product.

So, they should get here Thursday. I'm towing about 130 round trip to the track this weekend, so I'm going to see if I can get them installed before that. Still have some things to do to the track car before I go. I've got another event 2 weeks after that, so I wouldnt be too worried about running it as is for one trip, and then with the bags the next trip, as a comparison on the handling of the load. Regardless, when I get them, I'll post up some unboxing pics, and then I'll take some pics whenever I get aroudnd to installing them. As far as I can tell, I'll be the first person documenting aftermarket bags on a non SLS e70! Go me!

Good luck with the bag test.

On our other German SUV without SLS I use a WD hitch, and that works quite well. That has the added benefit of weight transfer which SLS doesn't do for you. That's why despite having SLS, I also use a tongue weight scale for setting up how I load, and I keep the overall trailer weight under 6000lbs.

It's amazing that only Dodge equips their pickup trucks with airbags in the back for load leveling. I've always hated the stiff feel of a pickup with an empty bed. And at $100 or so, an airbag is an inexpensive consumable considering the benefit of load leveling.

Are you pulling and open or enclosed trailer?

https://oi1244.photobucket.com/album...20-%20Copy.jpg

https://imgur.com/ypb1vtx

Lets see if that pic works- I'm towing a 18' open Big Tex. Two braked 3500# axles.

I haven't hit 6000# yet, and I really don't think I will. Car's about 3000 even, trailer is around 2100, maybe a hair over so I'll call it 2150.puts me at 5150, plus probably 6-800lbs of wheels and tires and random other stuff... so I suppose I'm probably cutting it close. The fact that you and a few others have accidentally hauled 9k+ makes me a little more comfortable with butting up against that 6k limit, and I certainly would rather play a little with the car's limit and have safe driving habits, than to play with the trailer's limit. The bags, if they do indeed work, will be a very inexpensive, great upgrade to the rear of my X5.

Still not sure if I'll be able to get my bags in before I tow the car home on friday evening, so I'm thinking I'll end up towing without them this time around. I might find time, but it depends on how today goes. Car's all back together and running great, new seat in, seatbelts hooked up, and I really just need to adjust the shifter a smidge and throw the rear bumper back on, and it's ready to be loaded up. I do really want to bring it home today if I can, so that I can get both my X5 and track car washed before my first event. If that ends up happening, then I might look at doing the bags tomorrow after I give everything a quick wash. Otherwise, they'll be in for the next event in 2 weeks.

Remember, towing can be safe if
(1) I find that pulling a trailer exacerbates the negative effects any front end suspension/steering wear. Wear in a control arm that's tolerable under normal driving is a real pain when trying to keep a 8.5' wide trailer centered in the lane at 70mph on a rutted highway, in cross winds, in the rain, in heavy traffic.

(2) Not less than 10% of the total trailer weight on the tongue. I setup at about 12%.

(3) I try to get as much of the weight in the trailer over the trailer axles, to minimize the trailers tendency to porpoise over bumps. The std X5 rear shocks lack a bit of damping, in my opinion, when you've got 600lbs on the tongue and another 150 of gear in the cargo area. My jack, fuel jugs, spare tires, tool boxes, etc are all situated as close to the axles as I can get them to keep the vertical "polar moment" of the trailer low.

(4) You already know this, but drive like everyone around you is an complete idiot. I've had people try to merge onto the freeway and right into the side of my bright red trailer. I couldn't make it more obvious... So I tend to drive ridiculously defensively.

(5) Don't a rush. The difference between going 85mph and 70mph only makes 30-45min different in arrival time for where I tow. So, I tend to take it easy.

Good luck with your experiment.

I appreciate the words! I'm probably going to end up loading post of my wheels into my track car just for the ease of not having to tie them all down, so the weighting should be good. I've been running 10-11% tongue weight. I also spend a good amount of my fair weather time on two wheels, so I tend to be pretty good at knowing everyone is an idiot on the road! And-85 mph?! That's wild. I don't know if I'll ever push it past 75, as even that is pushing it in terms of comfort while towing so much weight. I'm hoping the bags end up really helping the handling, which seems to not even be that bad, but it can't hurt to try to improve.

I don’t have the cojones to play on 2 wheels. I want to be inside not outside of the ODM tubing.

Ok... Installed the airbags. The don't seem to be leaking, so I guess I plumbed them alright. I have them at 30psi now and don't really notice a difference in how it drives, but I'm hoping it helps the rear end out when I'm towing. I should be loading up the trailer tonight, and towing my car home in preparation for an alignment and lots of tires.

Spyro,

This is really exciting. Waiting to here how it works out as it makes a larger group of X5’s suitable for towing duty (eg those without self leveling).

Bfeng- I just towed 30 miles home, at night, 1/3 through hilly windy county roads(35-45 mph limits) and 2/3 on a particularly hilly section of interstate (fr 80- 65mph). I was towing at 70 mph for the interstate. Rear bags are at 32-33 psi.

WOW! You can feel the weight, but there is much less “pushing” around from the trailer. The most noticeable difference is that the up-down bobbing over bumps from the trailer is entirely dampened out. Gone is the slightly wallow-y underdamped feeling of the rear end letting the trailer tongue pull it up and down, even over railroad tracks on local roads.

I currently have about 530 lbs of tongue weight, and I believe my trailer is likely right around 6300. That’s estimating on the very generous side, and I’m nearly certain that I’d be right around 6-6.1k on a scale. I’m going to up that tongue weight to right at 600 on my scale, which I measure at the tongue jack, which is about a foot and half back from the actual ball. This gives me a slight margin of safety on overloading the ball itself as per bmw’s recommended 600lbs max. I’m probably going to bring the bags up to 40psi. The car definitely squats a bit less, but it does still squat a bit. I’m hoping that a little more pressure evens it out with the slightly heavier tongue weight that I’ll be going with. I want a bit more stability for the long highway miles I’ll be doing come Thursday.



Overall, tomorrow I have to get my windshield sensor fixed by safelite first thing in the morning, and then go have the tire place mount 14 fresh tires on all my wheels. That’ll total to about 70 miles of towing, but will be a very busy day around that. Then, Thursday, I’ll leave on my 2200 mile journey. I’m not much of a man of god, but I’m beginning to pray for no issues! It’s a long way to be stuck from home...

@ spyro235 Thanks for following up on your original post. I look forward to hearing your experience with the air suspension add on.

We recently bought an AirStream NEST (4,000 lbs & 400 lbs tongue weight). It is light enough that we have very little squat. But I'd still like to smooth out the minor hobby horsing over railroad crossings, etc. So I'm very interested in your future posts.

Funf Dreisig

Just want to update this thread- towed 2300 miles over last thursday, friday, this monday and tuesday. The 2 weekend days were the drift event at the wonderful USAIR track in Shawano WI.

The drive was GREAT. The bags in the rear basically completely eliminated squat, with 600-625# of weight on the ball. The ride was splendid. Other then slightly longer acceleration and braking distances, the ride just felt like a normal X5 rolling down the road. Averaged 18.9 mpg through the entire 2300 miles, and didn't have a single issue the entire time. The 75+ mph downhills with crosswinds and lots of truck traffic made it a bit squirelly, but I rechecked the tongue weight and found I had only weighted about 525 lbs on the ball accidentally. Bumped it up to 600 even a few hours into driving by tightening the front straps and loosening the rears, and it became super stable again. By my estimation my trailer was anywhere form 6200# to 6600#, a bit over USA's rating, but well within my trailer's 7k rating, and the oem bmw EU rating.

Overall, the trip was a supremely comfortable one. Wasn't white knuckled, and had my brake controller set up to brake bias the trailer slightly, and I encountered one REALLY heavy braking situation along the way, in which I basically panic slowed from 75 to 30ish when a semi just didn't check his mirrors and came into my lane. Car remained super stable and tracking straight, while DUMPING speed. I was honestly impressed with the whole setup, especially with my continued confidence in the build quality of my Big Tex 18' trailer. I'm happy to answer any questions!

For reference, I ran my bags at 41PSI the whole trip. After the first day, I checked and found them at 36PSI, but I attribute that to the loaded wear in stretching of the bags. They have held 41PSI since then. The instructions say "for spring pitch gaps of over 1", use max 35psi, and for under, use up to 50PSI, and my gap measures aarroounnndd 1", so I set myself a 43psi limit. It still squatted a bit at 30psi, so I went to 41-42ish, and it just took the weight without issue.

Great review and feedback. I only get about 13 mpg towing my 5500lbs race trailer at 65-70moh, but it is big tall flat-front box. When I had a 850lbs Trailex open trailer I got closer to 16.5mpg on the highway. You should be very happy with almost 19mpg!

I'm sure if I cruised at your cruising speeds, mine would go down to the same. I'm still heavily considering trying out the 50i diff swap, which would lower the final drive from 3.46 to 3.15. If I remember correctly when I did the math, this would make the new 5th gear 5% shorter than our current 6th gear, so at worst case, towing would be done in 5th instead of 6th. For every day use, I'd love to have the longer final drive, but the car is geared phenomenally right now for towing. 95% of my driving is just highway commuting, in which I would absolutely love to see the 3-5 mpg gain that the 8 speed in the f15's get on the highway. I love the 27mpg I get with a heavy foot, and the 28.5-29.5 I get wiht a light one, but netting 32-35mpg on pure highway would be really beneficial for me over the next few years. I'm well on track to run about 40k miles a year, so it wouldnt take long to recoup the $3-500 in parts I'd spend on the differentials.

That is also phenomenal highway mpg when not towing. I average 27mpg @ 70mph actual (indicates 72mph on cruise control). The only time I break 30mpg is cruising on flat roads w/o traffic between 40-55 mph.

Oh man, I’ll get 27mpg if I’m real highway cruising at a real speed of 75-80. I’m deleted with dudmd stage 2.
I usually get 28.5-29.5 at 70 real speed on cruise control. I’ve gotten 31.4 when spending an entire tank at 68 real speed, and I haven’t had the patience to try slower.