For the last few years we’ve been running a set of winter tyres (Goodyear UltraGrip) all year. We do go over the border into Germany quite often so need them in the winter anyway but my thinking is, I’d rather have better grip in dodgy winter conditions than slightly worst grip in ideal summer conditions, they are better in the wet than summer tires which it is quite often here, they are on a C-Max so not exactly a performance car where the difference matters and the Dutch and Belgian ‘B’ roads are often un-surfaced sandy lanes so something with a more aggressive tread helps.
The first winter we fitted them the summer tyres were getting worn anyway so we just put them on the alloys, after the winter I looked into getting some more rims for a swap but it doesn’t make a lot of sense unless you can get really cheap rims. It makes no sense whatsoever to keep swapping the tires onto one set of rims, even if it costs a tenner per corner that’s 15% of the cost of a new tyre each time you change, and I don’t think that the winters wear 15% quicker than summers.