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.