Stealth Hitch FAQ questions the use of weight distribution with some vehicles - "Additionally, most of the vehicles we fit do not support these systems because the resistance to sway is forced back into the vehicle frame. Most of these vehicles are performance vehicles on light weight frames and are not built for these forces."
2012 x5 diesel here, towing about 4500lb dual axle travel trailer. No weight distribution or any other gimmicks here, Tekonsha RF brake controller and OEM hitch. Tows fine but would not do a cross country trip.
Here's an update on the completed OEM hitch harness install, with some learnings from the project and also some insights after the first tow.
My trailer is a 22' hybrid with a gross weight of around 5,500 lb and around 500 lb tongue weight. Not heavy and well within the rated tow capability of my F15 35d and the Curt hitch I installed.
If you recall, after installing the harness and tow module, I was getting a "hitch wiring" message. I had hoped this was just an issue of the coding not being done and not a matter of a problem with my harness install. I scheduled coding, but this ended up getting delayed by more than a month due to the X5 being rear-ended at a stoplight by an uninsured semi truck. The damage was not bad, but it crushed the area of the hitch wiring. The shop took a good look and assured me the wiring was fine, but now I was doubly nervous about the "hitch wiring" message.
Turns out I had nothing to worry about. With the rear bumper and hatch repaired, I re-scheduled coding and had the following items coded:
Encoded the trailer hitch module to the vehicle
Coded the park distance controller to disable the rear bumper when a trailer is plugged into the vehicle
Coded the stability control to adjust the suspension and brakes when a trailer is plugged into the vehicle
Coded the rear camera to add the hitch zoom feature
Coded the external lighting controller to add trailer light failure monitoring
I had the coding done remotely by Okee and it took about 3 hours. It was seamless with no issues. The hitch wiring message disappeared and all of the other functions came alive with no issues.
I finished off the system with a Tekonsha Prodigy P2 brake controller, which is the same unit BMW used to sell as the OEM trailer brake solution. The only thing that was not OEM was the plug where the brake controller plugs into the vehicle harness. I had to cut off the OEM plug and install my own 4-pin male and female connector where the brake controller harness met the vehicle harness. It hurt me to cut the OEM plug off of what was now the vehicle harness, but the aftermarket solution worked perfectly which helped me get over it. I was pleased to see the brake controller is fully integrated, including keeping the trailer brakes activated when I have the SAV brakes set to hold with my foot off the pedal.
Based on the recommendation of many others who have been down this road ahead of me, I ditched the weight distributing hitch and the anti-sway bar. I went to a straight ball with a 3.5" rise on the receiver insert. On the initial test drive, I tried to induce a sway on a deserted freeway going 45 and 60 mph. Gently at first, then a bit more aggressively. I was not able to get it to sway at all. The trailer rolled side to side a bit, but no sway behavior at all and the X5 quickly dampened out the rolling of the trailer. The 500 lb tongue weight did sag my rear end a bit, and there was also a lot of trailer-induced bounce in the rear of the SAV anytime I hit a significant dip or hump in the road. I changed the suspension to 'sport' and not only did it almost completely eliminate the bounce, but it brought the rear back almost to level.
Towing with the 35d is fantastic. I was averaging around 14 MPG on rolling highways with an average speed of 57. With the sport displays on, the engine easily produces 450 ft-lb of torque, even without pushing the engine very hard. The photo below was mid-way on a long steep climb from sea-level to around 1500' at around 5% grade. The 35d had no problem maintaining speed and did not down-shift more than 1 gear to pull this long hill. You can see the RPM have remained almost at non-towing highway levels.
Overall, I am really pleased with the vehicle as a tow-rig and also am glad now I went with the full OEM harness. There are cheaper and much easier to install harness solutions, but the OEM hitch wiring and hitch module ensures you get the full towing capabilities BMW built into the F15.
A forum community dedicated to BMW owners and enthusiasts. Come join the discussion about Bimmerfest events, production numbers, programming, performance, modifications, classifieds, troubleshooting, maintenance, and more! Bringing the BMW community together.