One way to tell if it is freezing outside is to watch the backs of your west coast mirrors, the CB antenna and the brackets on your hood mirrors. If you start to see ice building up on those, its a safe bet that its cold enough to freeze any precipitation on the road surface. When I first started driving, I was told that as long as I could see spray coming off other vehicles' tires, then the road surface was just wet, not icy. I can tell you from experience that, while that statement is usually true, it is not always true. If the road surface was snow or ice packed earlier, but now you see spray, just hold in the back of your mind that there could still be ice under the spray if the pack was thick enough. The top layer will melt, but not the bottom. The other bad news is that the melted top layer will almost always freeze back solid at night depending on the temperature.
Once you've determined that you're driving on slick road surfaces, my best advice is "no sudden changes of direction and no hard braking". Use your fuel and brake pedals as if you had an egg between your foot and the pedal. Do not break the egg! Your movements of the steering wheel and the truck should be slow and gradual. Don't let yourself get put into a situation that requires evasive maneuvering. Keep yourself as far away from other vehicles as you possibly can.
You need to know your truck. If you know how it "feels" when you hit a normal brake, you'll know when you "break loose" (lose traction) on an icy road. If you know how your truck sounds when it is running down the road on a normal day, you'll definitely know when you hear the noise the tandems make when they start to spin out as you cross a slick overpass. Also, if your truck is equipped with an on-board outside air temperature thermometer, know how many degrees it is off. Ours will read 4 degrees warmer than the actual outside temperature due to where the sensor is mounted. Four degrees can make a big difference in whether you are running solid ice or just slush.
With that being said, don't be a rolling roadblock either. My personal rule for speeds on bad roads is this: if the trans-axle differential is locked in, I should be able to do at least 25 mph and feel safe. If the trans-axle differential is not locked in, I should be able to do at least 35 mph and feel safe. If chained up, the recommended safe speed is no more than 25 mph. The operative words here are "feel safe". At the point that I don't feel safe, I park it. Contrary to what your dispatcher thinks or says, no load is worth your life or the life of an innocent person.
Speaking of tire chains: For the first 12 years of my driving career, my rule was that if it was bad enough for chains, it was too bad to go. Since we did a 6 month tour of duty for Interstate Distributors, I've changed that rule. For those of you unfamiliar with that company, let me explain. IDC is located in Tacoma, WA. Their drivers have to go through a chaining class during orientation. They expect their drivers to chain and run if it is safe to do so. Once we learned the "right" way to chain up, we have no problem "hanging iron" and running if we feel safe doing so. If you would like to see a video on how to properly hang your chains and a better way to chain, please comment below. You never know when adding a little bling to your ride will be necessary to get you out of a mess or to an icy dock.
Every one of us that runs West has to deal with knowing the chain laws for each state. The starting date for chains to be carried on the truck is different from state to state, as are the particular laws for each state. I believe that Colorado has the earliest compliance date for having to carry chains on the truck. Colorado chain law can be viewed at Colorado's Department of Transportation website. It states: "Commercial Vehicles operating on I-70 in either direction between mileposts 133 (Dotsero) and 259 (Morrison) from Sept. 1 to May 31 must carry sufficient chains at all times to be in compliance with the Colorado chain law." A good article about chain law broken out by state can be found on OOIDA's website. There are links to each state's website included. This article also mentions apps for your smart phones to keep up with state chain laws. I have not personally used any of these apps but might give them a look now that I know they are out there.
I want to give you my two most used links when Old Man Winter starts making himself known. You must be able to check weather on your route and road conditions in the states you are running through. I prefer the graphical forecasts at the National Weather Service. Learn to use this map as you plan your trip and you'll be able to route yourself around most bad weather. As far as road conditions by state, my favorite site is provided by the Federal Highway Administration. It is a state by state listing of all transportation sites. I especially love state websites that include live cameras on their road condition listing. Not only do I have the text version, but I can see the actual road conditions. Wyoming's WYOROAD.info is a lifesaver. These two sites are my best friends during the winter months.
The bottom line is that it is your tail in the seat. You are the only one that can make the Go or No Go call. Do not base your decision on what other drivers are doing or saying. Everyone has different skill and comfort levels. If you don't feel safe, find as safe a place as you can and park. Again, no load is worth your life or the life of an innocent person. The End.