First off have you done any changes to your suspension? If not the 235/45 should fit if you have the right backspacing ...17x8 with a 4 1/2 backspace should be fine. But I would go to your local tire dealer and have them try some on your car for size. Most dealers will let you see how the wheels and tires look before you buy, if they know there a future sell in it for them.
I'm running 245/45 17x8 on the rear and 225/45 17x8 on the front. But I also have the shelby drop so I had to roll my front and rear fenders.