the tires are pretty stiff, i really doubt there is much if any swelling at higher tire rpm.

from the looks of that graph, your definately not going to get the lean angle out of the 190-50 that you would from the 190-55. but as someone said, the more agressive ramp profile of the 55 would make it a little more difficult for mid turn correction aswell as working some S's. the 190-50, while not getting the full lean angle, seems to be a more "flickable" tire.