"Neil Gould" wrote:
What FAR says you may not run a tank dry?

The FARs address minimum fuel levels when you arrive at your destination.

I'm not aware of any such regulation. I suspect you're thinking of:

91.151 Fuel requirements for flight in VFR conditions.

(a) No person may begin a flight in an airplane under VFR conditions
unless (considering wind and forecast weather conditions) there is enough
fuel to fly to the first point of intended landing and, assuming normal
cruising speed

(1) During the day, to fly after that for at least 30 minutes; or

(2) At night, to fly after that for at least 45 minutes.

But that only talks about how much fuel you have at takeoff, not at landing.

I regularly fly something with two tanks and no "both" position (PA28),
and my preference is to arrive at my destination with more than 30 minutes
worth of fuel, period. I see no point in pushing those limits any more
than seeing how much over gross I can fly. IMO, such points are just
useless information. YMMV.

I also think landing with 30 minutes of fuel is too little. So, how much
is enough? Let's assume we can agree on an hour, which in a 180 HP PA-28
means about 8 gallons. You take off with 48 usable and fly for 5 hours,
leaving an estimated 8 gallons left. Which is a more useful configuration
to have at this point, an estimated 4 gallons usable remaining in each
tank, or an estimated 8 gallons usable in one tank and the other one dry?