I see there is a 250 gallon LP tank coming up on auction next Saturday. I'm still thinking of building a set up to refuel my LP tractor. I've asked before and looked through the archives some but couldn't get a straight answer. So my question is, would a 250 gallon tank have enough volume to fill a tractor tank (20-30 gallon) or would I be better off waiting until I find a deal on a 500 gallon? This would be just the venting method of refilling, no pump. At some point I also would be looking for a running gear or small trailer to mount it on for mobility. At what level would I lose the volume needed to transfer the LP, when it gets down to 100 gallons remaining, 50 gallons remaining? I will contact a fairly local coop that will do set LP setups and see what they say too. Thanks.