I'm going to say harshness/stiffness on the ride are 80% RFT, the bottoming out is 75% suspension. You'll have to change them both out to realize the benefits.
I changed out my tires first and was pretty happy. Suspension a month later after taking a light sweeping corner on the freeway when I hit a deep pot hole at 65Km/h that almost flipped the f'n car over.
"Our enemies are innovative and resourceful, and so are we. They never stop thinking
about new ways to harm our country and our people, and neither do we." - George W