Well, with an OE hitch you are rated to tow 6000 lbs then, less any load in the towing vehicle.

Is it an aftermarket hitch with a lower rating? And do you have brakes on the trailer?

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
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2003 X5 3.0 Steptronic, Premium, Titanium Silver
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