Disclaimer to Mighty Mouse: My words below aren't intended to have a go at you. I'm only quoting your comment as an example so I can offer a different perspective on the subject. I trust you don't mind me doing that.
Ok, here goes...
It doesn't matter to you and probably a few others on here (and other forums, when I come to think of it), because you ride in areas where there are gas stations within a 'Rocket 3 push down the road' distance, which, lets face it has to be a VERY short distance.
Count yourselves very fortunate on that score.
The ones that are not in that fortunate situation probably don't need to hear that. Instead they would most likely welcome advice about how far is too far before the gas runs out and they have to call the tow truck.
I speak from experience when I say that knowing a ball park figure on tank range is very important. I've never run dry ever, but i've come extremely close on a large number of occasions and it's stressful when you get caught short. This happens sometimes when you're touring and planning ahead isn't always as easy as it seems in reality.
I remember at least two such occasions. One when I was riding in Scotland and at 9 in the evening I was just a fraction too late to get to the only gas station in a twenty mile radius with twenty mile so my destination.
The light was fading and the temperature was dropping like a stone. I couldn't be sure if I had twenty miles left in the tank. I didn't think I was taking a gamble when I passed by the previous gas station because I knew there was one twenty miles ahead, but found it shut for the night.
So, to cut a long story short I knocked on some doors and found out who ran the station and asked them if they would help a good man out of a spot of bother and they kindly obliged, and I got to my destination without freezing to death on the next hill road.
The other was riding down through Germany on an autobahn in 96 F heat in the midday sun. Word of advice, be careful not to mis calculate your tank range on an autobahn, especially if you're not a regular on the route in question.
Bottom line, is folks aren't asking in order to weigh up if they are prepared to pay the gas economy of the bike, they are asking because they don't want to run out between gas stations.
Some folks seem to like to point out how people who ask the question somehow admitting that they are too tight to pay the fuel costs on a big and expensive bike like the Rocket, but that's not why they are asking.
With that in mind, I suggest it's the most helpful if we think we know how far we can go on a tank safely, we should state the figure and after half a dozen of us do that, and perhaps take an average, we most likely will arrive at a figure that can be considered a useful real world guide and a helpful answer to their question, because it does matter to some folks, and after all it's good to help a fellow biker out........as long as they don't ask for any of us to help them push their Rocket to the next gas station in Lochgilphead at night in the dark over twenty miles of twisty hill roads, blind corners and no sidewalks to push the beast on so they don't get hit by a night time supermarket delivery lorry....Forgot to mention that there's no mobile phone signal so not possible to call for a tow truck.......Did I mention about how I love touring Scotland on a bike....er....on a full tank of gas.
In the good old days (remember them? lol...) we didn't have fuel gauges. We had a fuel tap that had three positions. Remember those old things?
Well they were often not all that helpful a lot of the time in practice because the reserve gave you only about 8 miles till empty, but at least you knew exactly what cards you'd been dealt at the point you had to reach for the reserve position. When fancy gauges came along all you got was much more un defined as a countdown to zero.
Bring back the reserve fuel feature is what I say !
Triumph are you listening?
Probably not.