Need help with aftermarket wheels for 2005 645 and extended warranty policy

[sb06]

I am looking for aftermarket rims for my 2005 645. Where can I find the manufacturer's guidelines on rims for this car? I want to put 20 or 22 inch diameter rims but will that exceed the manufacturer's recommendations? I'm afraid that diameter will void my extended warranty policy because they exceed manufacturer wheel diameter specs. Anyone with insight please?



Thanks! SB06