When must tire chains (cadenas para nieve) be installed on a vehicle when traveling in Andean mountain passes (pasos cordilleranos) in Chile?

1. On all dry paved roads above 1,000 meters altitude
2. On the drive wheels (ruedas motrices) whenever snow or ice covers the roadway or when mandated by Carabineros de Chile
3. On the non-driven rear wheels of a front-wheel-drive car
4. Only after the vehicle becomes completely stuck