Answer: Yes, you can haul crude oil in 306-406 tanks as long as the vapor pressure does not exceed the design pressure of the trailer. Most crude trailers being built today in the U.S. and Canada are 407 Spec. Basically the same as other petroleum tankers, the requirements for a tanker hauling crude is based on flash point and vapor pressure. Some crude can be hauled in non DOT tanks but is usually not done due to the versatility needed to haul all crude product, ranging from heavy crude all the way to condensate. This is the reason why DOT 407 is usually used for crude.