30 inch OD Toyo Celsius CUV (Cute Utility Vehicle) tyres P235/65R18
For the past ten years or so, I have had summer tyres on my 19" rims and snow tyres on my 18" rims.
Getting older, I got tired of the twice a year changeover so I purchased "All Weather" tires of the 235/65R18 size.
This will be the first winter on them, but up here, we seem to get more ice than snow, but I think they will be OK. My Firestone dealer recommend the Toyo Cute Utility Vehicle tyres - guess he gets a good deal on them as they cost more than any alternatives I had in mind. Also maybe naming a tyre Cute may not be the best marketing ploy, hence they may have been some desperation and being an astute dealer of many years, he also recognized a "mark".
At any rate, the tyres are quiet in summer and yes, we now have ice on the streets that seems to be here for good, and traction seems OK. I would purchase the CUVs again.
Regardless of what you put on for one size fits all, I would recommend 18" rims and the 235/65 profile: I think narrow and lots of rubber between the potholes and the rim works best, both summer and winter.