I got my Cooper ATR's fitted to my X trail last year and i drove in some pretty crappy snowy and wet conditions up the Guthega Rd without chains. I actually didnt put any chains on all season. BUT i was driving back early season after watching SOO 2 from Jindy and it was the early season puke. Coming down the hill to Guthega Rd turn off slid the absolute crap out of it, it scared the sh1t out of me.
So definatley even if you have some beast of a 4WD and you think your tyres can handle it nothing except chains and studded tyres can handle ice!
Imagine playing football on a muddy field in your lightweight running shoes...hopeless, you need football boots. Same with tyres. I have been travelling to the skifields since childhood and have lived winters in Europe and North America. There is no substitute for a proper snow tyre (obviously non-studded for Australia). Your high performance tyre fitted to many new cars gives no snow and ice traction and the compounds go hard in cold weather. 4WD often doesn't help as many 4WD's are also fitted with high performance tyres or tyres with compounds and tread patterns completely unsuitable for snow and ice. Minimal or nil traction through 4 wheels is no better than no traction through 2, it can even be worse. I saw a lovely ML500 on low profile performance tyres do a beautiful 180 going down Buller last year...YIKES
There is no substitute for a genuine snow rated tyre that will actually bite, grip and evacuate in the snowy or icy conditions and doesn't go rock hard in the cold. Far superior to chains in lightweight conditions but obviously in real thick stuff you will still want chains. All of these modern snow tyres can be used on regular roads off the mountain too. Just take them off at the end of winter or get a spare set of wheels. Unfortunately they are hard to find in Australia. There are a couple of specialists around that have them though. I brought my Bridgestone Blizzaks back from the States a few years ago. Cost me a few hundred in freight but they are bloody marvelous. The difference is night and day and makes for a far safer journey. At a minimum if you are a regular vistor to Alpine areas you need an M+S rated all season tyre to give you any chance at road holding, something like a Pirelli Scorpion or similar will at least give you something to cling on with!
Have to agree with both of the last posters. Really good snow tires run huge rings around chains for ease of use and driveability. I was talking to a friend last week who is a highway patrol cop based in Hope, BC. The 400 km of roads in his patch includes the renowned Coquihalla Pass (Hwy 5), the Hope-Princeton road (hwy 3) and the Fraser Canyon (Hwy 1). The first two climb from sea level to 1300m in under 70 km, crossing the Coast Range which gets a buttload of snow (same mtns as Whistler, but a bit further south). Needles to say in winter these roads can be epic at times. The Coquihalla was closed twice this past winter due to avalanche control and untenable driving conditions. Anyway, in all this, the mounties choose to use their standard-issue Chevy Malibu patrol cars, fitted with Finnish-made Nokian snow tires. Adrian says they have the option of using a 4WD pickup from the general duties guys but he much prefers the smaller, more agile Chev. Not studded tires either, just super quality winter treads.
However... the sad fact in Oz is the cops will make you fit chains anyway and there's not much you can do about the other drivers around you except keep some distance.
You cannot use snow tyres in australia unless you want to BURN them up in just one season as they are just TOO soft for Oz conditions.
I may be wrong but in my OS experience snow tyres aren't fitted untill the temperature basically remains below about -5 due to the fact that you then won't get much in the way of thawing to produce water and thence ice when refrozen which is the BIG problem in Australia.
Chains make far more sunce in Oz than anything else because we just DO NOT get the constant conditions that make the use of true snow tires viable.
A lot of cops in Oz have no bloody idea when it comes to alpine conditions unless they have lived in the area for at least 5 years.
sly_karma is spot on with the relating of the Chevy's and their schmick tires. Less Mass = more controlability and less energy and grip wasted just controlling the vehicle.