On a Euro Tour of some sort, I generally use the 250 miles and Fill approach, although as Chris says, 200 is safer if you've been making good 'progress' on that tank of gas. A friend with a 5-speeder had to make a dash for Calais from deep in Belgium and had a gallon of juice strapped to the luggage rack just in case, as he thought he'd try to get to Calais in one hit. He cruised the Autoroute at about 4500rpm (85mph I guess) and ran dry at 295 miles. Just for reference.....!
