If you're lucky enough to reside in one of the southern states, where seasons don't change much beyond dropping from the 100s to the 80s, then you probably don't consider how much different winter driving is on your diesel.
For those of you who do get to experience temperature drops cold enough to crack a windshield, here's a few pointers we've gathered by experience, over the years.
If you encounter snowpack highways, ice or snow in general, you probably want to stick with a narrower tire. A 285mm section width would be about the max I would recommend. With a wide tire, such as a 325, the pressure-per-square-inch that the truck exerts on the driving surface decreases dramatically. In layman's terms, your traction is worse with wider tires. A lot of drivers equate a wider tire with increased traction because there is more tread touching the ground. That's true on dirt and dry asphalt, but not on ice or slippery surfaces. On ice, you need pressure. A heavy truck on narrow tires puts more pressure on the ice than a truck with wide tires.
Speaking of tread, those gnarly mudders that are on every show truck you see on the newsstands are fine in certain winter conditions (deep snow, mud), but are a hindrance in everything else. You want a tread that has as many edges touching the ice on the contact patch as possible. A mud tire with big solid tread blocks may have only 20 edges touching the ground per tire, where a good all-terrain may have 50-60 edges on the ground per tire. Siping is a very big help, even on mud tires, but it won't get you as many edges as a siped all-terrain or winter tire.
You should be familiar with winter grille covers. They are designed to keep the truck's diesel engine warm, since it has a harder time getting-to and staying-at optimal operating temperatures in cold conditions. They are best used when the outside air temps are at or below 0 degrees F. Running a grille cover will also get the hot air coming out of the climate control inside the truck sooner, too.
Most late-model trucks have a high-idle option that lets the truck idle at a higher rpm to get to operating temps quicker. On the flip side, many of the new DPF-equipped diesels don't like to idle for more than a few minutes or the DPF can plug up. Check your owner's manual.
Diesel fuel contains a lot of paraffin, and as the temperatures drop, that turns to a solid and the diesel fuel "gels" up. When diesel fuel gels, it won't flow through fuel filters, which means the engine doesn't get any fuel and won't run. Once diesel has gelled, it's a pain to get it back in operating condition. Basically, you have to replace all fuel filters (if you're running a lift pump or secondary filtration system, it adds up quickly) and move the truck to a warm shop where it can thaw out. Generally, if the fuel has gelled, the truck is probably outside somewhere and getting it back in a warm shop is not always easy.
One of our trucks gelled on a trip to Wyoming last winter. It was minus 30 degrees F. We had to send a flatbed up to get the truck and pay a shop to heat it up, replace the filters and get it running again... $500 later.
The cheap fix? Run an anti-gel fuel treatment in each and every tank once the weather turns cold. On extremely cold days, add a little extra; and replace your fuel filters often. Cold fuel has a higher chance of gelling in the filter if the filter element is dirty and restricted.