First post - woot.

I picked up an 05 4.8is last weekend. I have a Mammoth ski trip coming up, so I want to have chains just in case. I don't plan to use them, but may need to in an emergency. First question - has anyone used SCC Super Z-6 cable chains on the big 20s? SCC claims only 1/4" clearance needed on the back of the wheel. According to my calibrated fingers, I have at least twice that space back there. Second question - will they scratch my wheels?

Thanks for any feedback. I am looking forward to a long and enjoyable relationship with my X5 and this site.