For this round I suggest you stick with the stock tire size (225/45/17 front, and 225/40/17 rear)
Then as a next step, I suggest that you visit
http://www.tirerack.com/tires/tirete...nersmanual.jsp
and start reading as much as you can, To begin with you might want to check out the sections labeled "The Plus Concept" and "calculating tire dimensions"
I think you'll find that site quite useful and it would be worth while to get a better understanding of the most important part of your car.
Also, it's not necessary to type in all capitals, as it's considered screaming. And as a final note, you may want to cut your signature down a bit, as it takes up quite a bit of screen space, and hinders people's ability to read threads.