what size are the tires stock... I am having problems finding tires that fit my GS500 that are more sport than touring. Seems like with the smaller wheel hard to find something that will fit below a 150.
You might want to check out this board: http://www.ninja250.net/. There is at least one guy that races a Ninja 250 in California (Jim Race) that could probably give you the hot setup tire wise. A good tire for the street is the Pirelli M75 in 100/80 16 front and 120/80 16 rear. Stock for the rear is 130/80 16.