Long time reader, first time poster. This is a great website for wheel/tire specs:
According to this, the i30N non-Performance Pack's wheels (which look identical to the wheels on the non-Performance Pack VN) are 18x7.5, ET54, 5x114.3, CB 67.1.
Based on my i30N forum research, several owners have downsized PP i30N wheels from 19s to 18s for weight savings and/or more tire sidewall to handle bumpy roads. I plan to do the same, by a VN w/PP and downsize to 18s. Hyundai had a press release at SEMA saying they plan to offer lightweight optional wheels, so I'm looking to see how that plays out...they do offer OZ and BBS options in South Korea through their TUIX tuning subsidiary.