When driving a liquid tanker, why should you take highway curves and on ramp/off ramp curves well below the posted speed limits?

Tanks have a high center of gravity, which means that the weight of the liquid is carried high up off the road. This makes the tank top-heavy and easy to roll over. When driving a liquid tanker, it is important to take highway curves and on ramp/off ramp curves well below the posted speed limits because the liquid will shift to the outside of the turn, further increasing the rollover risk. Posted speed limits for curves are not designed for tank vehicles.