I bored out E53 wheels myself for my E70. You’re only taking off 0.75mm of aluminum from the hub bore surface. Easy to do with a harbor freight barrel sanding kit and a cheap corded drill. Unless you were completely ignorant and took all the material off of one side of the hub bore, it’s pretty much impossible to mess up.

Wheel spacers will not impact transfer case at all. Running different diameter tires front-to-rear is what destroys transfer cases.

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2007 E70 4.8i