Replying to Snowing Pres Day Weekend???

I'm coming up from L.A. to ski in Tahoe for the weekend. My question is how good is highway maintenance when going to Tahoe from the Bay Area? If its snowing, are chains required on the roads to Squaw/Northstar/Alpine or does Caltrans clear the roads constantly. I know Highway 80 is usually kept clear and even when it's snowing, I've never had to put on chains even on 2wd vehicles. How but the highways to the above resorts? I have 4wd, but will I still need chains?

Thanks for the replies.