[weberer]

Do you have some special winter tires or something? I also live in Helsinki, and would never bike in the winter since every path is packed ice and a thin layer of gravel. I slip enough just walking.

[hpaavola]

I use Routa from Suomi Tyres. Those are studded winter tyres. I guess Schwalbe Marathon Winter Plus is a popular choice in the category.

[cesnja]

You can buy winter tires with spikes.