In reply to yorkshireman:
> Not relevant this time of year, but its worth noting that hiring from the Swiss side in the winter means you get winter tyres (and maybe chains, I can't remember) since these are mandatory on Swiss roads, but not in France. The cost of winter tyres in France is usually ridiculous as an add on.
That's not 100% correct, snow tyres are recommended but not mandatory. A sign will tell you when they become obligatory. When you see the sign (Chains obligatory), chains have to be fitted or you risk a fine.