Actually, the distributor/sprayer truck mounted tanks, which do not spray asphalt, but rather a water based emulsion sealer, are heated, however asphalt trailers are not heated. Rather the trailers are highly insulated, with a full 6"-8" blanket of fiberglass insulation between the aluminum outer skin and the inner tank, usually aluminum, also. The hot asphalt grade oil is loaded at approximately 340 degrees F. and will hold temp above 250 deg. F. for up to 24 hours. The oil will stop flowing at approximately 225 deg. F. which will occur in about 48 hours. The trailer I pull in real life is like the smaller, 7000 gal max fill (water measure,) shown in the first picture alongside the 10000 gal. giant. However, I don't have the type of safety catwalk on the smaller one, mine is like the larger one. A full load of oil, depending on tractor weight, is between 5900 and 6000 gal, net, maxing out the axle weights. 12000/34000/34000 Asphalt oil and emulsion oil CANNOT be mixed! since the emulsion is water based, even two gallons in the bottom of the trailer, when the hot asphalt is loaded on top of it, will explosively erupt out of the manhole like a volcano!
Our trips, here in Iowa, cover most of the state, from near center, can be anywhere from 1/2 hour, to around 4 hours, one way. About 45 min. to unload, return to terminal, refill, and go again.