I have the exact same issue with mine, it's really scary sometimes when accelerating while changing lanes. I've balanced the wheels and done tracking but no change. The roads here are like where you are, the issue does away go away though when the road is flat/new. The tyre shop guy told me the issue might be reduced if the tyre wall is curved at the top instead of straight (mine are curved). I'm ad lost as you...this never happened to me before I moved here (norway).

BMW X5 4.8iS 2005

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BMW X5 E53, 4.8iS - 2005
Professional Stereo/Nav with DSP (modified BM54 module) - Converted to Eonon GA5166X with Reverse cam
4-Corner Air Suspension - Converted to BC Coilovers