Never, ever had the need to change the tyres to winter / summer ones from the standard ones fitted. All weekend I have been driving around Carmarthenshire in a Mercedes GLB with standard tyres. The temperatures have been -6 in places, ungritted B roads, housing estates, hills, farm tracks no problems at all.
Same yesterday, I left Carmarthenshire at 5am across black ice,\ through the country roads, along the M4 onto to the M5. Picked a passenger up on a hilly housing estate in Gloucestershire where it was snow and ice and then across country to the M4, Heathrow and back to Wales. This is near to 1:3
Changing tyres from the manufacturers specifications can affect the stability and safety controls designed for a specific set of tyre and wheel characteristics.
The other thing to take into account is that if there is a severe weather warning with the advice to only make necessary journeys, if you do go out against this advice you could get a difficult time from the insurance companies.