i can go with my 450x on 13/48 gearing around 200km to 250km on the road at 90km/h - 100km/h from 140km/h topspeed.
(i never ride it to reserve, so its all just aestimated.)
but dont forget i have the 3.6 gallon tank from ims and when you go offroad its less. i dont remember but i think it was 150km to 200km.
offroad i keep the tank full at all places its possible to get fuel because you never now when you can buy more.