Winter tires use the same pressure as shown on your door's placard. The key is to set it in the coldest temperatures outside that you will be driving in - first thing in the morning before you drive and not in the sun. I do this by leaving all my garage doors open for a few hours. Also, I fill and drain my compressor each time it's used. An alternative if you don't want to freeze your garage out is to add a few extra pounds of air pressure to each tire. And, since many vehicle's owner's manuals recommend operating winter tires several psi higher than recommended, read "Higher Tire Pressures for Winter Driving."
Snow tires are soft. You'll want to rotate them regularly and usually more often than your all-season tires. If you're looking for a mile schedule, I rotate mine every 2,500-3,000 miles. I like to keep my winter / snow tires wearing out at the exact same time and matching treadwear keeps them as quiet as possible. The moment I see a 1/32" deviation between axles, I rotate them - you could say I measure tread depth often! Metal tread depth gauges are awesome and that's what I like to use. However, they can tend to get expensive, so if you are looking for something that works well at a great price, take a look at the Dill Digital Tread Depth Gauge.
Designed to stay in contact with the snow and ice, winter / snow tires need to be connected to be effective. As it's not necessary to carry momentum when you have grip, you can reduce the vehicle's wheel spin. My car has Haldex four-wheel drive, the minute my traction light flashes I respond. I pull much larger vehicles out of snow drifts and ditches at less than 2 mph. Remember, keep that connected feeling.
Each tire manufacturer has their appropriate temperature cutoff, as snow tires wear faster in warm weather. My rule of thumb is 50 degrees Fahrenheit, when the temperature regularly is around this mark, I consider taking the tires off.
Since measuring your tire pressure is so important, be sure to take a look at our selection of air and tread depth gauges.