&quot;Do they really check every car, one by one, to make sure they have all the required equipment? Sounds time intensive.&quot;<p>On I-80, heading into Donner pass as you go through lake tahoe, CHP&#x2F;Caltrans does indeed check every single car as it drives through ... during dangerous driving conditions, that is.<p>They usually funnel the interstate down to two lanes and have two guys waving cars through, one by one.  They make sure that you either have a AWD&#x2F;4WD vehicle or that you have chains on.  Theoretically they are checking that AWD&#x2F;4WD vehicles, without chains, also have snow tires, but that isn&#x27;t really happening - they can&#x27;t tell that at the 8-10 mph speed you roll through at.<p>It may also interest you to know that there is a lively cottage industry of chain rentals and installers just prior to these checkpoints.  You can pull over just before the checkpoint and for $40 someone will quickly (and properly) install chains on your car, and then for another $20 at the other end of the pass, someone will quickly take them right back off.<p>This is regular and organized enough that you could absolutely drive through Donner pass in a blizzard, with no preparation whatsoever (other than $60 in cash).<p>It may also interest you to know (it interests <i>me</i>) that other, higher passes, with just as much potential for snow&#x2F;blizard don&#x27;t have any of these checks or precautions.  You can drive yourself right over vail pass (I70, Colorado) with whatever drivetrain or tires you like.