The idea is not to compare across brands, since each will have their own profile diff, but it is a good indication of what to expect, when considering tire size from the same brand...

I personally don't think a 180/55 will retain its shape in a 5.5" rim when mounted on a 6". What I have been searching for because common sense tells me the tire has to stretch a bit to reach the bead on a 6" rim.

I plan on trying a 190/55 when they come out, but for now I still run 190/50's. I don't believe the 180 tires on a 6" rim a better alternative than lowering the front 5-10mm to quicken it's steering & front end feedback...