I’m nagging all my friends to use winter tyres. One is resisting, saying it’s a ruse put out by tyre manufactures. I counter by saying you’re using the same amount of rubber no matter which set of tyres you’re on. Now if he said rim manufacturers, I’d have a little sympathy for his argument. As I have 2 sets of complete rims and tyres. Could you ask someone to write a definitive as to why we should use winter tyres in anything below 7 degs C? I know why we should, but there are a lot out there who don’t. One friend has a BMW 118D with runflats. He aims to use winters. I’m wondering whether he should get another set of ‘normal’ rims and ‘normal’ winter tyres, and simply do as I do: swap the lot each spring/autumn. What would be your advice considering benefit/costings?