Re: bmw wheels
I pondered this for a long time and got a set of used 18" BMW rims from a E46 2002-2006 era M3. The lug bolt patterns do basically match up ok even though very slightly difference as per the earlier posts. I haven't had any vibration issue due to lug pattern.
Only TWO big items of note : First - get your spacing correct as the OEM BMW rims vary all over the place and you may have to use "3 series fronts with 5 series rears". The M3 E46 set is very close (1cm off on rears at with offset of 47 front and 26 rear) - 8.5" wide with 225 tires in front and 255s in rear . The best BMW spacing I found on syty forum was actually off a set of Hamann HM2s - "18x8.5 rims (13mm rear, 38mm front offsets, 24 lbs. each). w Kumho Ecsta Supra 255/35/18's all the way around. I can't remember the name of who's truck but he got it right. The 1cm difference for me on the back is barely noticeable and since the set of used M3 rims was much much cheaper than new HM2s I'm ok.
Second - on the front the threaded portion of the spindle sticks out pass the cover. I have yet to decide if I'm going to cut it off allowing the cap to go on. The BMW caps can be flipped so as to show a silver side instead of the blue and white bmw logo. I plan to get a little GMC sticker logo for my centers.
Let us know what you get or if you have other q's, Pete