CRE Awareness and Operations Practice Test 2026 – Complete Exam Prep Resource

Capacity is the maximum volume a tank is designed to hold, measured in gallons, and it comes from the tank’s geometry and construction. For a DOT 406 cargo tank, this is a non‑pressurized liquid tanker used for flammable liquids, and the exact capacity isn’t fixed across all units—it varies by design. The important point is that the true value is listed on the tank’s data plate, which shows the maximum allowable cargo capacity and the fill/dispense limits. Before loading, you must check that plate to know how much you can safely carry. In practice, many DOT 406 tanks operate in the roughly 6,000–8,000 gallon range, with the exact figure determined by the specific tank you’re handling.