Did you get stock size tires?

How's the inflation of the the tires? Did you check it with a known good gauge?

If directional, are all four tires mounted with the rotation orientation set up for going forward?

If the tires are still super-new (less than a few hundred miles) then then can still be a bit hard/slick.

Also, the PS2's really are pretty amazing in their ability to grip. Perhaps the difference in grip between your PS2's and goodyears (and your now mis-matched fronts ard rears) is enough that you are now discovering the reduced fun that comes with less capable tires.

(That pretty much exhausts my tire-related cause possibilities.)