Do I need to carry chains in the car (often a paying optional extra in car-hire)?
Yes! During snowy weather, resorts restrict access to vehicles with snow-tyres or chains, and sometimes traffic police will not allow any vehicle on to the resort access road without chains being fitted. Chains can be bought at any of the garages in the area or can be requested as part of a car hire package (if you are taking a car locally). We'd recommend that you buy them in advance at home though, to ensure the correct size & that they're actually in stock. The colour-coded 'quick-fit' variety are usually the best option and make sure you buy the right dimensions for you tyres - one size does NOT fit all.
Aside from snow chains, snow tyres make a huge difference. Here is out top tip, if you are hiring a car from Geneva airport and you are given the option to rent from the Swiss side or the French side opt for the Swiss side. The reason being that it is a legal requirement during the winter months in Switzerland to have winter tyres so your car will definitely have snow tyres, it is not the same situation in France. Driving with normal tyres in winter conditions can be quite hazardous and make life pretty difficult.
If you do need to put on snow chains whilst heading up the mountain there are designated areas so make sure you pull off the road in time. Do not try to keep driving. The mountain roads are narrow so if you get stuck everyone else behind will be too and not very happy about it! With most people travelling on Saturday or Sunday and people both leaving and arriving the volume of traffic is huge so make sure you respect the conditions and that you are prepared. Read more about snow chains and winter driving in our Guide to Driving in the Alps.