Anyone used these things? It seems I cannot mount standard snow chains on our A4 as it has 235/45/17 wheels and it fouls something on the inside edge of the wheel arch apparently. I can hire these Spikes Spider things from roofbox.co.uk for a week. My questions are really: 1) Do they work. 2) Are they easy to fit. 3) Most important, do they trash your alloys? I guess you have to put up with the strange looking mounting ring fitted to the wheel for getting to and from the bit where you're obliged to put the chain bit on. That's if there's actually any snow in the alps this year! If anyone's used them I'd be very grateful to hear your review.