In addition to the snow tires, it'd probably be a good idea to add some weight
over the drive wheels. Four to six 12"x12"x2" concrete pavers will do nicely
without compromising your cargo-carrying capacity (volume) by too much.
I remember one winter, just after Christmas, the owner of a stone quarry/bungee-
jumping operation in Quebec (the "Elastic Bandit", yes it has a web-site) was
kind enough to plow a trail from the road in to the quarry for me so that I
could look at some stone.
When it was time to leave, I had to turn the car around in an area that wasn't
ploughed out and my 245 wagon just sat there in not-too-deep(6")-but-wet-snow
spinning its snow tires uselessly.
Maybe if it was a standard transmission, I would have gotten out.
In any case, it being a quarry, there were many boulders about and it only took
a few loaded into the back to provide the necessary weight for the tires to get
some bite. Lucky for me because without a cell phone in an area not frequented
by people till Spring ...
Of course, there are times when even extra weight won't help.
Like when, in a blinding blizzard, you hit a dip in the road where the snow has
filled-in 2 crotch-deep and your vehicle floats up on top of the snow and it's
snowing so hard that the hole you're digging around the wheels in an attempt to
find the road surface, fills in faster than you can dig it out.
That's when you leave the vehicle, snowshoe or ski home and wait for the snow
plough to dig out the road and haul your vehicle out two weeks later.
But don't (like an acquaintance who was caught in the same storm) pour boiling
water into the packed-solid-with-snow engine compartment in an attempt to melt
the snow. He ended up with an ice cubed engine compartment which didn't thaw out
till early Spring. Of course, he didn't own a Volvo. Volvo owners would know
better. Right ?