What is the purpose of the Central Tire Inflation System (CTIS / Reifendruckregelanlage) on certain specialized heavy all-wheel drive trucks?

1. It maintains one fixed high road pressure and prevents any driver adjustment
2. It transfers air between tires so all wheel positions always have identical pressure
3. It allows the driver to adjust tire inflation pressures from inside the cab while driving, lowering pressure on soft mud/sand to increase tire footprint and traction, and raising pressure for high-speed highway transit
4. It replaces the need to inspect tires for damage because pressure is monitored automatically