The confusion arises from the fact that in certain years in Canada (and perhaps in other countries) the 128i Sport Package featured staggered 18-inch Style 263 wheels (see this post:
https://www.1addicts.com/forums/showthread.php?t=379231). I don't know when they discontinued including the Style 263's (maybe after MY 2011?), but my Canadian 2012 128i M Sport was sold with 17-inch Style 207s.
So my guess is that in Canada, if you're looking at a 2011 or earlier 128i Sport, it will have 18-inch wheels, but when BMW introduced the M Sport package in 2012, the regular Sport package went from 18s down to 17s.