ive heard of people going up to a 160/60/17 but i dont know how safe that would be for a 3.5 inch rim... the aprilia rs250 has a 4 inch rim for that tire size.
I just changed out my rear tire a few weeks ago and went with a 150/60/17 jsut cuz of the options and surprisingly there was plenty of room left. The tire is clear of the chain guard and the swing arm. THe mechanic thought wed have to shave the chain guard a bit but there was plenty of room left over.
Have a look using the search bar, been talk of plenty.
Its not just a case of how big you can go, but how it effects turn in etc of the bike, the smaller rubber on our bikes is pretty optimum, with 140's giving a small benefit. Some have also said that going larger than 140 can lessen the effective turn in, making the bike less 'flickable'. This may only be noticeable to someone who knows how to push the bike to the limits.
Been working on new project.Should be done today.
I want bigger tires too but just put a mammoth rubber on a bikini rim is not my way.
I bought a band new er6n(Ninja 650 ?) rear rim which is 4.5" wide compare to 3.5" fron Ninja 250.
Required some modification though.
ON 4.5" rim I can put 150-160 tire.But will go for 150.