I just went through this, and its easily solvable. Think about what the 55 series rear tire did. Not only did it raise the rear end slightly, it also placed more weight on the forks. No big deal, really, btu this bike is heavy. When you start moving weight around, we're talking WEIGHT!
Try removing preload from the shock..try 5 clicks. Then take out 1/4 turn of rebound damping. Then test. If it helped, but did not entirely fix it, add a line.
Do the rear first as its entirely possible to tune the advantages of that taller tire right out of the system. More preload up front will not let the front end settle as much dropping into a corner.
Obvioulsy, this assumes bearings, and tire installation are correct. Plus, my trunk adds in all sorts of odd behaviors at "legal impaired" speeds.