I gotta agree with smartdot. I have 17" Lorinser speedys and am quite happy with them. I didn't put them on for better ride quality, but for better handling and aesthetics. If you want a softer ride, I'd recommend going with 15" rims. Almost everything involves some sort of compromise. Only you can decide what is best for you. See if you can drive, or at least ride in a Smart with 17" rims to be sure. I'm in So Cal, so if you're down this way, let me know, and we can arrange a test drive.