215 45 18's?

[msix]

I recently purchased and installed 18" wheels with 225 40 kuhmo tires to replace my stock 16's Putting them on seems to have brought out ever rattle and creak the car is capable of. I could live with the harsh ride, given the handling improvement, but the noises are driving me crazy! Anyone had a chance to drive an 6 with both 40 and 45's? If so is there a big difference in ride quality? How do they compare to the stock 17's? I also figure that going from 225's to 215 would help a bit. Just wanted to check before I spend more $$$.