allensteiner wrote:i doubt you'll need a spacer at all. why don't you take your stock wheel off, put the new one on and see if it fits without touching anything.
Unfortunately, I doubt this is accurate.
The stock OEM 2006+ M wheels are 47 and 50mm offsets (depending on whether you have the 18" or 19" wheels). If you can make them fit on another Infiniti or Nissan without spacers, I would be extremely surprised! These stock rims will contact suspension components all too easily, I think.
So, in most other Nissan/Infiniti cars, you will need a 10 to 25mm spacer (depending on car and how "flush" you want it, etc.), and that is horribly large IMHO ... your opinion may vary! I think it is better to sell those OEM wheels and get something that is a better fit for your car without spacers!
Z