Get snow socks, they will fit even wide tyres on large rims. Have used snow chains in Greece on my dads Bm. Once you had them on for a while they stifen up on the inside and a pain to remove. Plus you have to remove as soon as you hit clear road. Snow socks are the best option, roughly between £50 and £60 and they will not strain the tyres. A nice accessory.
Good, but snowsocks are a pain to fit to wide wheels with limited clearance between rubber and bodywork...I know, I've tried 245/40/17 on a C270...could not actually get my hands in to fit them without jacking up car.