Pat wrote:

Biking on packed snow -- especially snow over packed snow -- is very
tricky because the tires aren't formulated for it. The rubber is too
hard.

Not any bike tires I've used. How do you know this? Bike tire rubber
seems softer than car tire rubber.


Also, at 100 psi, you don't have enough contact with the ground.
So bikes and motorcycles go away when the snow starts.

You can have as much contact as you want, you can use treaded and even
studded tires. Lots of people ride bikes all winter in snowy climates --
I do.