Is it ok to go with a smaller wheel and Tire? Say a 17 all the way around? The reason I ask is that I want more sidewall for auto crossing events. Sharp and quick turns are not so friendly to the stock wheels and tires on the 2005 G 35. Not just for the events but to drive to and from with them also.

 

I have stock 17 on my car now....

 

Get yourself some front and rear swaybars and some endlinks. That will vastly improve your cornering abilities.

 

17's will be fine. some G's come with 17's stock.