Prob not the smartest idea in the world, but I'm not the smartest person.

So I'm driving in next couple days to St Moritz for a quick stay before returning to Zurich.

I had booked a random car but on advise from other people upgraded the car to some AWD model.

But then someone mentioned that you might need snow chains....I thought the roads would be clear enough (presuming car rental has winter tyres..) and can you even use snow chains on AWD?

Looking at my car rental it does not seem to come with chains. Is it obligatory to have these? Also what realistically are the conditions going to be like? Driving will be done in the evening so not expecting any great sights which is a shame (unless anyone has recommendations of a particular route to take?)

Thanks.

Yes you can use snow chains on AWD - often just on the front wheels (so you can still steer), but in principle you can put them on all four for maximum grip.

It is obligatory to have them available on some roads, I don't know about the route to St Moritz, and it is also obligatory to not drive dangerously which could be interpreted as needing chains.

The best route to St Moritz is on the train in the carriage with panoramic roof. The best road route (imo) is Albula pass, but that's closed in winter.

Wrong. It is obligatory to put them on the wheels if mandated by the police or signage. In some instance, if this happens, AWD cars are exempted https://www.20min.ch/story/auf-diese...n-988003494717 . But not always. Be aware: it is all wheel drive, all wheel braking offer all cars and thus an AWD is only slightly better when it comes to stopping. If you do not have chains with you, you can simply not proceed with your journey hand have to use an other road or wait till the conditions are better.

There are two possible main routes to get from Zurich to the Engadin and St. Moritz in the Winter. The Julier pass road (which goes up to 2284 m) and the Vereina tunnel (car train) route were St. Moritz is the highest point of the journey. Two more possible escape routes are via Landeck Austria and Maloja-Lago di Como. If conditions are bad expect very long wait times at the Vereina tunnel.

Usually the road over the Julier pass is either free of snow or in such a condition that any car with winter tires can drive over it. Currently the road is "covered in snow" (Schneebedeckt), as are the roads in the Engadin. But there is no need for chains.
See the official map here: http://www.strassen.gr.ch/sites/stra...and/karte.html

Be aware that "covered in snow" (Schneebedeckt) is used pretty liberally. Be not disappointed if the road looks like this:



Source: https://www.nationalpark.ch/de/besuc...ebcam-schloss/

__________________
"Okay, I just hope we don't wake up on Mars or something surrounded by millions of little squashy guys."

True, that is definitely the law according to Art. 29 SSV.

However, the several times I've been asked about chains at a police checkpoint they have only been checking I had them, and in most cases the snow chain sign was not in place further up the road and they were not needed.

So I guess there are cases where they are non-obligatory but only if you fancy your chance arguing with the police about it.

It depends on the weather. There are temporary road signs that say chains are mandatory. If the police considers the road is too slippery, they put the signs and you need to mount them (explanation in German from TCS) https://www.tcs.ch/de/testberichte-r...igatorisch.php

This is the road information site of Graubunden. Today, it seems you can drive up to St. Moritz only with winter tires. But, the weather is weather. It will be not funny to get there and then cannot return as desired. Even less funny to have to buy snow chains up there to be able to leave http://www.strassen.gr.ch/sites/stra...and/karte.html

That is a useful link thank you. Seems a bit strange they would make snow chains mandatory, but the rental cars do not come with them? (Though I concede that most of the roads do not need them). So having AWD isn't enough to be exempt?

That map is good, no snow chains obligatoty as I see it.

Two options then, drive over Julierpass or take the Vereina car train in Klosters and then drive up the valley. Latter is certainly the less wintery choice, but I remember driving Julier in winter was always fine. Snow on the road, but generally well prepared road.

Don't forget the disclaimer below the map

Fine, so in worst case you buy a set of snowchains at a gas station in Savognin. Assuming it is not a Sunday and not after 7pm.

Take the Maloja, only 1815msm.

Tom

7 pm? More like 7 am. If chains become mandatory they will sell like hot cakes.
https://www.suedostschweiz.ch/touris...n-schneeketten

I guess it's one of those personal responsibility situations.

But, is it worth for OP to spend 300 CHF for snowchains (new) for a rental car? Maybe just ask the rental company for the chains. They're offered as an option like child seats. That's the reason they're not included by default, some people don't need them, make a profit from the people that ask them.