I have a 08 G37S Coupe, What is the best wheel and tires set up? Like size of wheels and tires... Please help...

 

The best size is what you prefer. Use the search function and make a decision for yourself, there is no "best".

 

and depends on your drop...... on oem height?

 

My front 245-35-20 rear 275-30-20 with Vertini black Concave rims. No rubbing or problems.

 

My G37s is stock no drop.

 

Best to improve the car performance wise? The smallest diameter wheel/tire combination possible. Preferably a square setup (same sizes all around).

I'm sporting 18" wheels (G37 Journey) on my car and it freaking stops on a dime (with bad tires) and has great acceleration. Also, my fuel economy is good for winter weather.