Usually full front and rear, so about 50 gal total. I run off my front normally, and I never let it run lower than half a tank (unless on a road trip) so if for whatever reason I need to just up and leave on a moment's notice I got at least 150 miles on my front and another 450 or more miles on my reserve tank which will put me pretty much halfway across the country before I really have to refuel. I also have two 6-gal cans that I keep full at all times, so that's another 150 miles range should I absolutely need it...