Hey all-
Looking to get into a MY13 G37x Sedan with sport package.
1) looking to go with 20" wheels, same width all around.
2) no fender rolling
3) a nice drop that doesn't require cambering.
What am I looking at as far as offsets, max width without rubbing (I'm think 10" all around), and springs with mild drop/no cambering required? Thanks

 

Welcome to the site!
Having a wide aggressive square setup can be done, but the front fender isn't rolled like the rear so what will fit in the back may make contact in the front.
You could go w/ 9X20 +35 offset all around, that would be an easier fit w/ 245/35/20 tires, here's a good thread w/ that exact fitment and a mild Eibach spring drop, this is A RWD.
https://www.myg37.com/forums/g37-sed...ld-thread.html
For the AWD X models, Swift lowering springs seem to get the best reviews, drop is similar to Eibachs but have a softer ride. Should be able to get your alignment close to spec, might be a bit out w/ camber but not enough to cause excess wear as long as you rotate your tires a bit more often.
If you go 10" rims you'd need offsets in the +45 range and run a slightly stretched tire setup, probably stretching 245/35/20s. And you might hit that front inside fender edge under heavy impacts.
HTHs

 

if i do decide to go RWD, are swift spring still a good compromise between drop and ride?
Could I go with a 9.5/10.5 or 9/10 setup with 235 front and 245 rears?

 

Swifts do get good reviews for RWDs too, just put Swift springs G37 in google for good feedback.
My RWD is lowered more than Eibachs/Swifts to zero tire/fender gap and I run 8.5x20 +40 245/35/20 and 10x20 +45 295/30/20 for a flush rear fit and inside the fender about 7mm in front. You could run a 245/275 245/285 or 245/295 staggered depending on your drop & offsets.
You can run staggered setups in AWD but diameters are more critical, especially the difference between the F&R tires.
If you live in an area where AWD isn't needed, or rarely needed I'd opt for the RWD, more aftermarket parts available, less mechanical parts to deal with as well and if you want a manual transmission they're only available in RWD. If you consider a RWD look for an S model, it will have the big brakes, tighter seats, LSD rear end, sport bumper and a few other goodies. Here's a pic of my staggered setup for reference.

 

I'm coming from the land of the four rings. I was going to go S4, but have stumbled upon a deal for a similarly equipped G37X, that destroys anything I could find for the S! So, looking on coming to the dark side, even if it's only for a little while, and want to keep the AWD for twisties fun .
So, with a 20x 9 square and 255 I should be OK? What offset would work for that?

 

Again, take a look at this thread for the fitment, it's on 245s but you'll get the idea and the offsets are +35
https://www.myg37.com/forums/g37-sed...ld-thread.html