[ZPrime]

The Federal US DOT, in its infinite wisdom, doesn't require snow tires in snowy parts of the USA.

Because of this, we also don't get any info on our door sticker for suggested tire pressures for a snow setup.

Here's the door sticker from a UK car, which includes "M+S" (winter / "mud and snow") pressures for the factory OE winter configuration. PSI are in italics in the lower section of each row. (The upper / bolder part is in bar and uses a comma instead of a period to separate decimal places, because Europeans are weird.)

In the event the picture doesn't attach below or isn't visible, here's the info in text form (should also be indexed by search)...

Factory winter setup is presumably staggered front and rear, although I don't know what size wheels are used. The tire size is definitely different though.
Front: 235/40R18 95V XL
Rear: 255/35R18 94V XL

So, the front actually have a higher load rating (95) than the rear (94), and they are most likely "performance winter" tires like a Michelin Pilot Alpin, rather than a "snow & ice" tire like the XIce. (You can guess the type of tire based on the letter, which is the speed rating... V = 149 MPH. Most ice & snow tires are more like an H or T rating, which are 130 and 118 MPH respectively.)

With a "normal" load in the car, they specify 30 PSI front and 33 PSI rear on this winter setup.

With a heavy / maximum load, they go up to 35F / 39R.

Also worth noting - the maximum load PSI for our summer setup, which (once again) the stupid government doesn't require manufacturers to list, so it is omitted from our door stickers. 39 F / 42R is how much air you should use if you are regularly carrying 4 passengers or a bunch of stuff in the trunk.

[stefan]

30psi in the cold is a good rule of thumb. If you're filling up in a warm garage add about 4 psi if you live in a very cold climate.