Maybe I'm too late to the party, but I just finished upgrading my wheels to a 1" downsize on all four corners.I also found the lightest wheels I could to minimize unsprung weight. Everything worked well and the rough road handling is SO MUCH BETTER. The suspension feels much better over bumps and more in control during turns. Here is what I did:
Fronts:
Konig Hypergram 47MG Wheel 17x8 5x112 Grey 45mm
2pc 10mm (.6) 5x112 Wheel Spacers - Hubcentric Billet 66.56mm Hub Bore
225/45R-17 Vredestein Quatrac 5 XL
Rears:
KONIG HYPERGRAM 18x8.5 5X112 ET43 MATTE GREY
2pc 15mm (.6) 5x112 Wheel Spacers - Hubcentric Billet 66.56mm Hub Bore
I used the original FRONT tires- Continental 18s.
All 4:
20 Pc Black Locking Spline Lug Bolts M12x1.5 + 2 Keys 33 MM Length

There was only one small issue with fitment: The front wheel bearing covers did not fit inside the new wheel hubs so I have to... massage them a little bit. In the mean time I am relying on the wheels to keep moisture out of the bearings.
Hope this can help!