yeap from the 20's I went down to 18 inch Titan wheels, complete solution.
My basic/easy reccomendation as someone who went through the same stage, get the Michelin PS4S for your new set, they have better ride than the supersports.
I went for 18s because I track, most people in for looks go for 19s
my estimate is that 75% of the harshness is from the 20 iinch rims.
hope this helps
