I live half a mile up a track in rural Aberdeenshire. I'm a convert to having a second set of wheels with winter tyres on - they make a massive difference to getting around without running a 4x4 all year. 15's will allow the use of 195/65 tyres which are the same diameter but narrower than the 205/55's which will also help.
We're not all boy racers you know - some off us are old gits!!