Offset help

[TonyVA]

Had been driving my E28 until a post fell on me...now is either E46 M3 cabrio (summer car) or 2001 X5...love the way X5 drives. Bought some chrome Style 65's (Silver E53) and want to know what offset I should look for inthe back to put 275/45/20 in the front and 305/40/20 in the back. Planning on getting hubcentric spacers if needed but don't want to get an array of them as they are not cheap and getting your money back could turn out to be a hassle. Anyone that can help your input is welcomed!!!

[LeMansX5]

Are the style 65 OEM or replicas? OEM style 65 were
245/40 R18 front
275/35 R18 rear

I have seen these E39 wheels on E53 though

[TonyVA]

The only concern I have is going to 20"s will I have to increase the offset to keep from rubbing anywhere? As soon as I figure it out I will post...also, has anyone lowered their E53? Did you use H&R or Eibach?