On snowy days there may be a "Kettenpflicht" on some roads.

Symbol is this one:



But in most cases, if you have an 4x4, it's not required.

Here you can know if there's a "Kettenpflicht" before hitting the road: http://strassen.gr.ch/sites/strassenzustand/karte.html

Purple marked roads require snow-chains.

Remember you can not drive above 50 kmph with snow-chains. Remember to remove them before entering the speedway. Don't be this guy.

If you're renting a car, the car should include snow-chains in the baggage. At least Mobility cars have 'em.