There's alot of commentary in this thread, but I'm not sure if the original question was answered. 21" wheels are a "odd" offering for a couple reasons:

1. Limited Demand- with the advent for the 745, most people with a luxury sedan want 22" wheels. Also almost any vehicle that can comfortably fit 21's can also accomodate 22's so most just "skip" the 21s. IMHO 2 of the best candidates for 21's are the w220 S class and w215 CL class MB.

2. Limited wheels - off the top of my head Lowenhart LD5/LD1/LSR, Lorinser RS8, Donz (cant remember the model), AutoCouture, Makaveli, and a couple of the more "bling" companies make 21's. Not even 1/8th the amount of 20s and 22s out there.

3. Limited tires: 245/35-21 SP9000, 255/35-21 P- Zero, 255/30 & 295/25-21 Continental. (there may be one or 2 more, but those always stick in my mind). Limited tires limits the applications (try lowering your G35c on one of the above tires).

The funny thing about the G35c is it has such aggressive factory offsets, that even with 20" wheels, it can still look "wimpy". If you want that wow factor, you would probably be better served to try to go crazy on width and offset with 20s (maybe 9.5fr 11rr to really get wild).

Good luck

 

You can get a custom set at my boys shop if you really want them.

 

oh god...17 base rims to 21...wow...
i wouldnt mind putting them on but...it's hard to find 'nice' one...on G. IMO;;;