What is the base of stability for an aerial apparatus when parked with the aerial device stowed?

The base of stability for an aerial apparatus when parked with the aerial device stowed is indeed represented by a rectangle formed at each corner by the tires. This configuration provides a stable platform since it encompasses the entire footprint of the apparatus, allowing it to distribute its weight evenly across the ground.

In practical terms, this rectangle formed by the tires creates a defined area that helps prevent any tipping or instability that could compromise safety. By ensuring that the aerial device is parked on a level surface within this rectangle, the likelihood of lateral movement or upset is minimized.

The triangular base and other options do not accurately reflect the broader and more stable footprint provided by the rectangle formed by the tires, which is crucial for maintaining the stability of the apparatus during operations or while stationary.