The standard tire on the back is a 200/50R17... I am currently using a 200/55R17, and it fits fine. The tire is about 2cm taller in diameter, and that doesn't cause any problems at all for height issues. It does throw the calibration of the speedometer off, however, and I am now showing 2-3% less than actual, rather than 2-3% more than actual.
Can you post a picture of your bike from the side so we can see the visual difference (if any)?