* Tank size: Tank sizes vary considerably, ranging from 100 to 300 gallons or even more in some cases. Larger tanks obviously allow for greater range.
* Fuel efficiency: This is heavily influenced by the truck's weight (including cargo), aerodynamics, engine type and maintenance, tire pressure, terrain (hills significantly reduce fuel economy), and driving style (aggressive driving burns more fuel). A highly efficient truck might get 7-8 mpg, while a less efficient one might only get 5 mpg or even less.
* Cargo weight: Heavier loads drastically reduce fuel efficiency.
* Road conditions: Headwinds, steep grades, and poor road surfaces all decrease fuel economy.
Considering these variables, a reasonable estimate for a *typical* big rig with a moderate load on relatively flat terrain might be anywhere from 500 to 1000 miles on a full tank. However, it's entirely possible to be outside that range, significantly less or slightly more, depending on the factors listed above.
