I think the style and color wheel is a perfect choice. But in my opinion I think the wheel well swallows that 18. I would like to see a 20 in the rear and that 18 in the front.
More proof that wheels and stance are everything! Looks killer!
I know it's just a photo-chopped tire but I would go for a little more sidewall to close up that gap showing in front and back of the rear wheels. That's a big car so it will take some sidewall to get the proportions just right with 18s or go to 20s like Steve said.