Do I need a transmission cooler for towing?

[JCL]

Originally Posted by ard

I agree it isn't published, and I assert BMW does not do this for a reason!


Where is this "published" for the USA, or is it a reference to a hitch rating?


I don't think BMW has published a US vehicle tow rating... there is nothing in any of my 2010 manuals...and if it isn't ON the car or IN the manual, then BMW hasn't "said" it. From a legal/regulatory perspective.


A

I have to use the E53 as a reference, and the E83, as those are the two models of OE hitch I have installed. I don't have the E70 instructions handy, but I can't see why they would be any different.

For the E53, and the E83, BMW provides the vehicle ratings in a technical document that is packaged with the hitch. I wanted another copy, so I had my dealer print me one out, it has an SIB number. That document stated the following:

Originally Posted by BMW E53 Hitch Instructions (extract)

All X5:
Max towing weight for trailers w/o brakes (on and off road) 1650 lbs.
Max tongue weight for trailers w/o brakes (on and off road) 330 lbs.
Max towing weight for trailers w/ brakes (off road) 3300 lbs.
Max tongue weight for trailers w/ brakes (off road) 330 lbs.

8 Cylinder/Automatic transmission:
Max towing weight for trailers w/ brakes (on road) 6000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

6 Cylinder/Manual transmission:
Max towing weight for trailers with brakes (on road) 6000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

6 Cylinder/Automatic transmission:
Max towing weight for trailers with brakes (on road) 5000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

If I had a clean copy, I would scan it for you, but the last time someone asked I typed it, so I just cut and pasted here.

For the 2004 model 3.0, with the 6 speed automatic, this was updated to 6000 lbs. The 5000 lb limit remained for the 5 speed GM automatic transmission.

There was also a table (and a label for the hitch) that specified maximum hitch ball dimensions from the receiver, in terms of reach and drop. Those limits were based on the vehicle structure, not on the hitch fabrication, in my opinion, since the hitch is far stronger than the rear pan of the X5.

I conclude from the above that BMW did calculate the safe load based on vehicle platform limits, even down to the transmission model, and not on the hitch rating, since they all used the same hitch.

BMW did not need to put this in the owner's manual (but it would have been nice if they did) since the owner's manual states that no non-BMW accessories are permitted. In other words, the vehicle tow rating with an aftermarket hitch is zero as far as BMW is concerned. Use one at your own risk. Buy the BMW hitch, and they provide the info. My hitch was built in the US, and the instructions were from BMWNA, not BMW CA.

Perhaps someone who has installed the E70 hitch themselves can clarify what the hitch instruction manual states for that model.

Edit: Sorry, hadn't read scollins post yet. There are the BMW weight limits for the E70, from the E70 hitch installation instructions, part number 01 29 0 412 716. Those instructions state that the hitch kit includes a capacity sheet (handout) to be left in the vehicle for the owner.