Keep in mind it was a Tuesday with me arriving at the TH at 4:30 PM so I had the whole place to myself...no other cars at all. I made it to the Summer TH with a Ford Escape that has almost new tires. A lot more snow on the road above 11K. There was one snow spot I didn‘t like below that dilapidated cabin (abandoned railroad worker dorm??) that is just off the road. The majority of trouble spots were higher up the road from there. As of this evening I would say it would be better to have a high clearance vehicle with good tires...definitely not summer tires! Mine are all season and did pretty well. Keep your tires in the existing ruts and you should be ok. I could hear the belly of my Escape scraping on the snow in some spots when my tires were in some of the deeper ruts.
Photos (click for slideshow):