Towing - Standard vs. Load-Leveling Suspension

[Bayerische E53]

Originally Posted by digdesign

Hey Guys. I'm mew here. Been lurking on the forum as I've been shopping for a pre-owned E70 35d. Thanks for all of the useful info. Here's my question:

I'll be towing my E30 M3 on an open aluminum trailer. The total weight of the loaded trailer will be roughly 3800lbs (2590lb car + 900lb Trailer + 300lb spare tires & tools). Shooting for 10% tongue weight would put it at about 380lbs on the coupler. On top of that, I'll also have 170lbs of equipment in the back of the X5. So the total load on the rear axle will be in the ballpark of 550lbs.

My question is, does 550lbs necessitate the load-leveling suspension? I know that it will be "better" with it. But can anyone comment on the amount of sag I might experience with a standard suspension?

FWIW. I do want the load-leveling suspension, but it's hard enough to find a decent used 35d, let alone to find one with option 220 and no 3rd row. (I don't want the 3rd row since I'm towing long distances and need to carry a spare)

Any advice would be greatly appreciated.
Thanks
-Mick

Hi Dig,

I used my E53 NON-SPORT to tow my open trailer and racecar; total weight was 5,000lbs with about a 550lbs tongue weight. I did not use a WD hitch with this setup and the truck towed a treat. There is obviously a bit of sag, but nothing absurd. I did around 10,000 miles with this setup without a hitch (no pun intended). At 380lbs tongue weight, you should be just fine.

Also notice that the weight on the rear axle will actually be more than 550lbs because the 380lbs you're exerting on the tongue is a lever, exaggerating the amount of weight on the rear axle. Either way, based on the weight I was putting on the tongue, you should be more than fine as I was within spec. Regardless, make sure to check your tongue weight with a scale to really get an idea of what weight you're placing on the tongue - the last thing you want to do is underload the tongue, making the trailer have a tendency to want to buck up and down, lifting the rear of the X5 (no stability).

Ideally, you'd want to use at least an "Equalizer" brand WD hitch, but it isn't terribly necessary - especially with only a 380lbs tongue weight.