The stock 19s look nice, but every pothole I hit I am expecting to blow a tire and makes for a pretty rough ride on an otherwise pretty smooth suspension system. The narrow sidewall just isn't a good functional design. I already hit a nasty pothole and had to get the rims repaired and my tire has some permanent deformation (not causing any air leaks). When I go to get new tires (only 19k on the car), and let me tell you I can't wait to replace these ****ty Falken Ziex ones, I want to get 18 inch rims and sell the 19s. Has anyone else done this or is there any reason I will have issues? Like brake rotor clearance or sidewall contact. I'd obviously pick the same width or slightly narrower if needed. Costco has some decent alloy wheels for $250 a piece.

 

Your reason for going to a smaller diameter tire is very valid. You should see what The Tire Rack has to offer?
Tires By Brand | Tire Rack

As for fitment that all depends on the wheel you are looking at and the advice for fitment from the retail source helping you make your choice.
I changed my 18-inch OEM wheel for 17's. My reason was the wheel I wanted. But I still would have chosen to go small 17 regardless. The sacrifice IMHO in what may have been less then 1-2 MPG was a fine for the improved steering and softer ride quality I gained. I am also preparing to install Cork Sport Big Brake Kit on the front with those 17's and they will fit with NO clearance issues. In fact, they will fill the wheel very nicely.

Good Shopping for your new wheels!

 

Just did this, March 1. Dropped off the 19” Ziex 225/45R/19’s to the 225/55R/18’s. Speedo has zero adjustment. Perfect match. With new rims. Discount Tire. I have another post on here in greater detail. Do it! Enjoy the softer, quieter ride. Best!!!!