How does the amount of liquid in a tank affect how it should be loaded, considering legal weight limits and surge?

TANKER LOADING CONSIDERATIONS: (1) WEIGHT: Liquids vary in density (weight per gallon) — heavy liquids mean you may NOT be able to fill the tank completely without exceeding legal gross/axle weight limits; you might carry a partial load of a dense liquid; (2) OUTAGE (expansion room): Liquids EXPAND when they warm up — you must leave room ('outage') so the expanding liquid doesn't rupture the tank or overflow; different liquids expand by different amounts; (3) SURGE: Partially filled tanks have MORE room for liquid to surge — affects handling; SO: The fill level depends on the liquid's weight, its expansion properties, and legal limits — it's a balance, not simply 'fill it up'; drivers must understand these factors to load legally and safely; some loads will be partial due to weight; outage must always be provided; the interplay of weight limits, expansion, and surge makes tanker loading more complex than dry freight; this is tested on the tanker endorsement.