Zilon

If it helps anyone in future, after quite a lot of research and calling up roofbox.co.uk who have great staff, I went with Polair Steel Grip which are the type that sit on the outside of the wheel only. They explained that the risk of traditional chains in my situation isn't so much in the diameter, rather the clearance on the inside of the wheel to the suspension and various sensors, apparantly recent cars tend to have more and more sensors for safety but it leaves less clearance. Especially at full lock the chains could drag on these and cause major damage. The Polair Steel Grip are very similar and similar price to the Konig K-Summit. There's not much info on Polair in English (French brand) as they're not so well known here, but I found a french article which directly compared the two models and concluded performance was very similar but Polair was much easier to fit, hence the choice. Unfortunately this type of snow chain is at the more expensive end and cost £270 but for me the decision was more about peace of mind in that I expect there's a good chance I'll need to use them a few times over the next 10 years (I drive every year for skiing) rather than just for the sake of compliance with French laws and expecting I probably wouldn't have to use them (such as a one-off trip to a low-altitude ski area or merely passing through the alps in winter). If it was the latter I'd just have stuck with Snow Socks which I already had, but I read quite a few more accounts of how they can rapidly shred on tarmac, which isn't not going to be viable to fully avoid, and secondly in heavy snow which can happen rapidly and unexpectedly at high altitude, chains do a much better job. There was an interesting alternative Polaire GRIP polyurethane which are a type of plastic with similar performance and the benefit they can be used for moderate stretches on tarmac, but while these are fully legal in France they're not in Austria so I didn't want to risk it in case I go Austria in future.

Just summer tyres. I considered getting winter ones but I would have had to pay over £200 per tyre and then change then at either end of the trip every year.

Yes it's for Val Thorens in France, which is a very high ski resort and I've read that snow chains are frequently needed to be used, let alone just required by the police. I have taken snow socks on previous trips and not needed to use, but after hearing about some friends shredding theirs and getting stuck I figure I'd rather invest in chains for the peace of mind.

THanks all, good advice hadn't considered rope chains nor the inner wheel clearance.

After some advice on snow chains. My Superb iV has R18 wheels. In the manual it says chains are only suitable for 16 and 17 inch wheels, but not for 18 or 19 inch. However, limited clearance is very common on a lot of vehicles nowdays, and there are various chains designed for this. Many of the non-super-expensive options in this category seem to use chains with a 7mm or 9mm profile. Of course they all say 'check compatability' with your car to indemnify themselves, even though most cars with limited clearance just say not to use snow chains. Am I right to figure that since the Superb can have 19 inch wheels which is 25mm greater diamaeter than my 18 inch wheels, then I should be completely fine with even 9mm chain profile, which would add 18mm total diameter? Are there any other considerations I'm missing? I am able to reach over the top of the wheel under the arch to fit them, so it's only about whether they would actually contact and damage any other parts of the car as far as I can tell.

Oops yeah got confused there. Thanks for the reply, that's good news. And I would also assume the car needs to be on, not planning to run the cool box while at vehicle is off.

I have recently got an electric coolbox for camping and picnics. Since the Superb's 9V sockets are permanently on (rather than switched with the engine), I'm careful to not let it run down. But I do tend to keep it charged and drive electric whenever I can, which got me wondering - the coolboxes can use quite a bit of power and I'm told they can drain 9V batteries in a few hours if left on. In a ICE car the alternator continuously charges the 9V battery so this doesn't matter, but if I'm driving only electric, does it also charge the 9V or do I risk running the 9V battery down? In a long camping trip this probably doesn't matter as I would be driving on petrol, but I can often go weeks running the car on just electric with regular day to day and weekend use.