← How ProTankr Works
How the weight plan works
The only defense against an overweight ticket has been to either load on an axle scale or load conservatively, because doing the real density and thermal-expansion math by hand, for every load, at every terminal, isn't realistic on a schedule measured in minutes.
ProTankr runs the actual ASTM D1250 calculation automatically, the same standard terminals and weight enforcement use, so you can load to your real legal capacity instead of a safety margin built on guesswork.
API gravity and densityAPI gravity is the industry standard for measuring how light or heavy a petroleum product is. A lower API number means heavier product, more pounds per gallon. The plan uses the most recently observed API at this terminal (entered by the last driver) to calculate how many pounds each gallon will weigh at the planned temperature.
Temperature correctionPetroleum expands when warm and contracts when cold. The same number of gallons weigh more at 40°F than at 90°F. The plan corrects for this using the ASTM D1250 thermal expansion formula, the same standard used by terminals and weight enforcement.
Target weightThe target weight is your gross vehicle weight goal, tare weight plus payload, set below the legal limit for a small buffer. The plan fills compartments to hit this target, not to maximize gallons.
CG sliderThe center of gravity slider shifts weight distribution between the front and rear of the trailer. Moving it moves gallons between the compartments. Moving it forward puts more weight on the drive axles, moving it rearward shifts weight toward the trailer axles. Use it to optimize axle weight distribution for your specific terrain and conditions, or simply to shift things for a slightly faster drop when delivering.
