We are going away Jan to March this year getting the ferry to Santander and driving through Spain to Portugal. It occured to me that I might need winter tyres, especially if we find ourselves going over higher ground. I have Michelin Agilis but I don't think they're all season so have been looking at changing them to Michelin Agilis Crossclimate camper. I have six wheels on my Hymer S650 - the question is do I need to put winter tyres on all six wheels? Pretty expensive if I have to do that! Hoping I can get away with only 4.