I make that drive every year and just got back 2 weeks ago. As you know in the Sierra it can snow (and snow a lot) any day of the year so there's always the risk you have to deal with it. Having said that, the drive down 395 is for the most part flat and high desert and the storms are sort of blocked by the mountains. You will be driving along the eastern flanks rather than through them and there are two summits you have to pass but the ascents/descents are gradual (easier than I80) and even in a snow storm they are usually benign compared to going over Donner Summit (the pass just before Mammoth is called Deadmans (?) and even that is cake compared to Donner). I would say most 2WD passenger cars with snow tires would be fine even in the snow. If you have to chain up it will be for a short distance. My advice would be to drive the speed limit through the small towns and stop for BBQ in Walker (if the Mountain View BBQ is open; its on the side of 395 and you can't miss it). Its a really nice drive.