95 S320 ride height question, and tire chains
 

Can someone tell me how to correctly measure the ride height on the rear axle on the S320, as well as what is't supposed to be in the ride height range??
Also, After getting stuck a few times, and barely making it out, I was looking at getting some tire chains for my car, and was thinking about this set:
http://www.rackattack.com/product-pages/thule-cs-10-passenger-snow-chain-104.asp?utm_source=avantlink&utm_medium=product-feed&utm_campaign=avantlink-affiliate&utm_term=100204104
Would these links clear properly??
I asked at the dealer about getting chains, and the parts and the service managers said they had never heard of a mercedes with tire chains.... I'm pretty sure they do, as my car has a switch to activate when chains are in place.