I've just bought a set of traction chains for my Mk3 18" wheels, and noticed in the Ford Kuga Mk3 brochure, that you must not fit chains on the larger 19" or 20" wheels. Clearance I suppose. On the 18" and 17" the chains must not be more than 10mm. Could come as a shock to some with the bigger ones if they sometimes need to fit them. I have them for going in and out of slippery farmers fields with the caravan if needed.