I've used the SCC "Z-chains" on my prior 7-series (Z-563) and the Highlander Hybrid. They are low profile and can be bought at reasonable levels online ($50-$80/set). I typically only buy fronts as they have the majority of the traction in slick environments. Here is a link to their site. You will need to pick out your vehicle in their system to find the right model number...
http://www.scc-chain.com/Traction%20...Trac_home.html
Here are the ones I am considering for my 20-inch (214) rims. The size is right (based on SCC's table) but the Amazon site indicates that they are not designed to fit my vehicle so one of them is wrong. You may want to call them directly to verify which ones fit your particular tire/vehicle.
http://www.amazon.com/Security-Chain...keywords=SZ435
PS - I have already sent them an eMail asking for guidance specific for my '12 X5d with the optional 20" Sport rims (model 214)