And a 55 series tire is actually going to be 10% taller in total (0.75" taller), since the 50% and 55% figures are for a cross-section slice of the tire, not the entire tire. (say 'entire tire' 55 times real fast)
entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire, entire tire
Whew.
All I know is that 190/55 would be too tall for my really short legs.