What is the tire sizes I should be running for best performance and handling, and acceleration?

I want to keep the cars engineering close to stock as possible to drive the car the way it was suppose to be built, and allow the car to perform at its maximum potential?

Do i run a 245/35/19? or a 245/40/19? front?

What about rear?

 

The stock setup is 245/40/19 rear and 225/45/19 front. For the stock wheels the most popular setup seems to be 275/35/19 rear and 245/40/19 front. I believe this is also the closest to the original tires diameter.

 

225/45/19 front will wear off much faster than rear 245/40/19's. Our G37 if we don't replace alignment kit. The outer part of front tire will wear off much quicker than the inner side. Especially if you drive and corner at greater speed.

So when you have to change your front tires, instead of buying another set of 224/45/19 for your front. Place 245/40/19's from rear tire to the front. And purchase for few dollars more 275/35/19's, for the rear tire.

And 245's lasted little longer than 225's when placed on the front.

Other than economical reasons your G37S will look much better. Drive will not alter as long as you don't modify the car further.