Getting sad now.... as reading up further from other bmw forums seems that this is an issue on other xdrive cars too, and me going and putting on tires with a different tread and possibly size has thrown things out, if there is a mis match in size and fronts are less than 2mm than rears the transfer case will spin the wheels faster to compensate?
https://f30.bimmerpost.com/forums/sh....php?t=1393497
Hmm and please see this by Q7silver posted , Im gonna have to go try measure rolling circumference first and make sure they are rears/fronts are within 1% of each other. And checking tire pressures too...wish me luck