Hello tsastor,

I would say that it is highly unlikely to get winter tires / snow tires in California, even in the winter season. As far as i know (from many rentals in the US) the concept of winter / snow tires is unknown, at least in the so called southern states (I have been to California, Nevada, Virginia, West Virginia, Oregon, etc. and NEVER heard of them over there).So I would not count on that.

Regarding the upgrade to a 4x4, from what I hear the chances are getting smaller since these type of cars are not requested tha toften anymore and the rental car companies are not purchasing these cars a lot anymore. This is mainly due to them being unable to remarket (=sell) them after the rental period and the manufacturers are not giving attractive buy-back deals out anymore.

I would go for reserving a 4x4 and not hoping for an upgrade, and if you go through the consolidators/travel agents, the price difference is not very big.

Enjoy your trip!!