Can you post a link of the one you're referring to? Perhaps we're speaking of different ones.

http://www.1010tires.com/WheelOffsetCalculator.asp

It takes everything into consideration really. Your BMW tells you the recommended tire sizes. I came with 18x8 ET 20 w/245/40/18 rubber.
I wanted to upgrade to 19 or 20. I chose 19 based on several factors.
Car specifically calls for (in the doorjam) 245/2519 and 275/30/19 which will give you the SAME overall diameter as the stock setup.
I have style 128's ET 14 on my rear which is JUST perfect with no rub, no spacers and hold specs.
Overall diameter is overall diameter of the tire, who cares about the diameter of the wheel as it should be an obvious thing.

This is probably a dumb question, but can anyone tell me the best places to buy OEM rims? I'm assuming there has to be other places other than the dealership, right?

Mazekid, looks sick!!! I was thinking about this same setup on my xi (128s), and wanted to know where you purchased them from? May I ask how much? Thanks!

1550$ NEW. FROM A BMW DEALERSHIP IN NEWPORT RHODE ISLAND. I WAS THINKING OF SELLING MINE AND GETTING ANOTHER SET BUT I DUMPED 1000$ IN MICHELIN PILOT SPORTS A/S... ID BE ASKING TO MUCH :rolleyes:

Looks good!! Def. Needs a drop! I suggest H&R sport springs, it will look so much better after the drop.. Good luck and thanks for sharing the cool pics!! :)

I did drop it already :)

Try finding a local Bavarian motor works they may be able to help. Ask your local BMW dealer where you may find one :whistle: