If you hire a car in Germany, Austria or Swizerland between October and May, the hire care company will charge you extra for the privilege of Winter tyres - and it's not optional. Local laws apparantly. I've no idea why they aren't included in the price since they won't let you have the car without them.
I've driven to the (French) Alps for the past 4 winters in the Omega on Summer tyres. I do have snow chains, and without them there is no way we would have got there on 2 occasions, or back on 3 occasions. The locals consider us (Brits) mad to even attempt it on summer tyres.
I think next time I'm going to take their advice and get some cheap steel rims with winter tyres on. Traveling down hill with chains on the back, and summer tyres on the front can get effing scary. You daren't touch the brakes cos the fronts will just lock up and then you're a passenger heading straight to the scene of the accident. I found the best way was to put the car in neutral and use the hand brake to control the speed, and then just pray that the front tyres have enough grip to have some influence on the direction of travel. One of the few occasions when a FWD car is an advantage IMHO.