BMW M850i wheel spacers vs xDrive?

[DO11CTR]

Hi, I want to fit 10-15mm spacers on the rear wheels alone, but was querying whether this would affect the xDrive system in any way?

I know differing tyre sizes(height) can affect 4wd systems, but didn’t know if the same is true of spacers.

I feel the front wheels can get away without needing spacers.

Proper wish they fit wider wheels & tyres to the rear of this car!

TIA