I always put holes in the top of the tank metal filler tube of my 25 plate 1250R, to allow the air expansion trap to escape and enable more fuel into it when filling up. I only do this overfilling when I am filling up immediately before heading off on a long run with the BMW Club. I’ve had no problems with fuel spilling out because of this action, with the bonus it regularly provides the range in excess of 250 miles before I need to refuel.