"The car has 140K now. I recently replaced my worn Michelin X-one tires
with Goodyear Assurance Comfortred which are known for
their smooth ride. However after replacing the tires, I noticed that my
bumps cause shudders in the chassis and many bumps and expansion strips
cause harsh impacts."

I would have a tech look over the entire suspension...you may have some
worn bushings or other components.

Also, did you notice a difference in the ride when you replaced the
struts at 90k? My guess is that it stiffened up some.