Commercial winter tires
If you use commercial winter tires, of so-called all-season usage, they can delivery you safety throughout the year and allow you to use only one set of tires for year round use. This will improve your safety, while still only using one set of tires.
Good quality tires have the advantage that you can retread the carcass. Retreading can only be done as long as the carcass is in good condition and it can only be done once or twice. Retreaded tires that have been retreaded with top of the line tread is as good as a new tire, but it can drastically save you money as retreading can be done at a fraction of the cost of new tires. In addition you are reducing waste as you reuse the carcass.