is the rear ride hight adjustable on your bike? some are a pain, some are easy. if its easy and you don't like how it rides. just lower the back a few mm and your back to pretty much where you were. the 55 will have a different profile, but normally guys like that better. makes it tip into a corner easier.
I had to go the other way around when I first got my bike. it called for a 190.55 and no one had them in stock for almost a year. so it put the 50 on there and raised the bike back up to the stock hight and it felt the same to me. since I don't really push it on the street either. maybe the track guys would notice.
oh and if you have a rear hugger, it may rub that too.
__________________