FACT: You do need SNOW CHAINS (even on a 4x4)

Beware of false advice from friends and internet. From our experience, the best advice is on the AA site.
Here are key questions and useful tips.

Required by law?
Like all(?) French ski resorts, the roads into Combloux have a blue sign, as shown, marked "Equipement d'hiver Obligatoire". The law since 1977 requires metal chains to be carried and, when conditions require it, to be fitted on at least two driving wheels.
Even if you have snow tyres?
Yes. The law stipulates chains and there are conditions when chains do provide better grip. (Even though snow tyres usually work as well, or better!).
In fact, we rely on snow tyres and carry chains in the boot only because of the legal requirement.
Even on a 4x4?
Yes. In practice a 4x4 with snow tyres can go right through the season without the need for snow chains but by law they must be carried in case they are needed. If you fit snow tyres they should go on all four wheels.
We have seen 4x4s stopping to put chains on. If you fit chains on two wheels of a 4x4 the other two wheels are more likely to slip so do check the manufacturer's advice for your particular vehicle.
What's the risk?
Without snow-chains or tyres you are more likely to suffer delays; or damage in a low speed accident. Perhaps the worst risk is that if you are involved in an incident or cause a hold up which is judged to be your fault, not having chains could invalidate your insurance even for a 4x4 with snow tyres. (It is also worth knowing that, unlike England, there is a "good samaritan" law in France requiring people to stop and give assistance if needed.)
Are there many accidents?
Yes, cars often go off course, but they are quickly dealt with. I think it usually involves bad driving. The important thing is to drive carefully, avoid braking and stay in low gear ("Which" advises selecting a high gear in order to reduce torque - I disagree). On hills, leave plenty of space for other drivers to make mistakes. .
Are there spot checks?
Never in my experience around Combloux. I have heard of the police in other areas turning people back if they don't carry chains but have not heard of any spot fines.
Would you buy or hire chains?
If you are hiring the car, make sure chains are provided even if there is a surcharge.
For your own car, it may be worth hiring chains if you only expect to make one trip! However, hiring them in the UK can cost more than buying them in France (from Feu Vert or most petrol stations and supermarkets south of Dijon).
If you are keeping the car, think very seriously about buying winter tyres. If not, I would advise you to get good chains because they are easier to fit, grip better, and are more durable. Buy online or in France otherwise they can be expensive. Make sure the exact tyre size e.g. 195/55-14 is listed on the packaging.
... but I would always choose to buy winter tyres. I carry a cheap pair of snow chains bought in France but only to satisfy the legal requirement (insurance against insurance!)
Why buy Winter Tyres?
Winter tyres are for normal road speeds and distances, in cold weather. Below 8°C they are safer than summer tyres, above that summer tyres perform better. In the UK they are often called "snow tyres", which is misleading - and they do not have studs or spikes!
Winter tyres cost about the same as summer tyres and while they are on your summer tyres are not wearing! The rubber contains silica for flexibility and they have a deep tread with lots of sipes (cuts to provide more gripping edges and stick to snow). It is amazing how well they grip on snow.
For safer driving in the UK, we fit winter tyres in November and switch back to summer tyres after March. Ideally you should fit four but for ski trips in the past we've found it effective to just replace two on a front wheel drive car. We bought two steel wheels so they could more easily be switched.
You don't need expensive brands, mid-range tyres such as Kuhmo perform well. We used to own an Audi Quatro with top-of-range Michelin winter tyres, our current Sköda with Kuhmo tyres is just as good. (We bought new alloy wheels for £102 each)

Tips - on driving on snow

There is a definite skill to be learned before you can get the best traction up a snowy slope. It is a matter of keeping the wheels slowly turning and staying on fresh, firm or frozen snow.

Tyres grip better when it is really cold. Traction is more of a problem when temperatures are near to zero, when ice build up under the snow, or when slush forms. Freshly falling snow can be a bit like soap flakes to drive on, seems ok but don't hit the brakes.

Local roads are ploughed pretty quickly and effectively between about 8am and 5pm but chains are often needed during and for a few hours after snowfalls especially if you arrive late in the evening.

At our apartments, the bend coming up from chalet la Biche can be slippery so it is sometimes wise to either park at the top or keep chains on overnight.

If you get stuck in snow without chains, a rubber floor mat might just provide that extra bit of traction to get you free.

Tips - on using chains

Chains should be fitted tightly over fully inflated tyres. Usually you pass a cable behind the tyre, loop it together on the top of the wheel and lower it to the far side of the tyre and then use some kind of rachet or tensioner to tighten the chain from your side. Practice in advance - Kerbside at night in a blizzard is not the place to read instructions!

Keep a torch and old gloves or a rag in the car. Old ski gaters are good to protect your ski jacket. The canopy of a petrol station can be a welcome place to fit or remove chains. At our apartments it is smart to drive down into the car park under the tennis court.

Keep elastic luggage straps in your boot. They are very effective on a broken or loose chain.