I just purchased a wonderful 2010 535i xDrive Touring and put snow tires on the original wheels. Those are BMW Style 277 which are 8x17 with a 43mm offset. I have a set of BMW Style 74 wheels which were on my (now totaled) 2005 X5. The 74s are 8.5x18 with a 48mm offset. First, I believe I'm correct in assuming that the Style 74s are also 5x120 bolt patterns, though I may need different length bolts. According to my calculations, the 74s on the 535i xDrive Touring would have 11mm less clearance (.433 inches) and only stick out another 1mm. The concern I have is on the inside clearance as I've heard the Touring is already cramped for space (especially on the rear). Anyone have experience with these wheel fittings?
Can;t say I have tried to fit them. The bolt pattern is 5x120 but the hub size might be different I would look into that first. Then try a test fit to see if they do actually fit.
See this, also look up wheels for your car on tirerack.com and you can scope out the offset range for 8" & 8.5" rims. They're almost assuredly both 5x120, probably the same hub bore, but that's not too hard to measure or test with a check fit. http://www.rimsntires.com/specspro.jsp