All those official pictures of the 135i show it equipped with 264-style five spoke wheels.
According to the German dealer brochure, there are three additional wheel styles to be available (207M, 263, and 261M):
http://www.mediafire.com/?8z0agjj0vgz
The 261M wheels are new, for front 215/40 R18 and rear 245/35 R18 tires.
In my opinion, the double-five (i.e. ten) spoke 261M-style wheels make the car look much sportier, though they may be a bit more difficult to clean. They tend to look lighter than the 264-style, but what really counts is which of the two has the lowest angular momentum.
Since BMW doesn't provide data, the best way to test this is to simultaneously let both wheels roll down a gentle incline that levels off to a long horizontal surface, side by side. Whichever wheel has traveled the farthest upon stopping is the one to get, because it will accelerate faster, brake better, go faster, and consume less energy, even if it would happens to weight the same as the other one. Reverse positions on the second trial to confirm the result.
With Photoshop, it ought to be possible to get an idea what the car would look like with the 261M-style wheels.
Do people agree that these wheels give the car a sportier look? Can anybody find out if they also have less momentum?