welp, thinking of going up this weekend, to try and see the "fire wall". And yes, I have a rear-wheel drive Model S and no chains. I've only been in the Bay Area for two years, and have not driven up the Sierra in the S (did go to Tahoe in a previous Jeep). I'd love to do that this weekend, but doubt I'll get my hands on the unicorn chains that work on this car. Anyone have a set I could borrow/rent? Anyone want to experience the slow rear wheel drive Model S of their dreams while I drive their D?