Proper storage of your boat and trailer during the cold winter months will not only extend their life but also the life of your boat trailer tires. While not everyone has the luxury of storing their boats and trailers in a heated storage unit, doing so limits thermal cycling from vast temperature extremes that occur during the winter. It is also a good idea to jack up the frame of the trailer to take some (or all) weight off the tires to prevent a flat spot from developing after enduring weight for months on end. Scattering fabric softener laundry sheets about the interior of the boat will also keep various critters like mice and squirrels out of it and from shredding the material for nests.
If storing outside, be sure to park on a patio or wood blocks to prevent the trailer tires from sinking into the soft ground during the spring thaw. This also prevents the tires from enduring a long period of contact with a wet surface, which contributes to tire rot and wheel rust. If you have the time and energy, the ideal tire precaution in extremely cold climates is take them off the trailer and store them indoors. If keeping the wheels on the trailer, be sure to have a large enough tarp to cover them to prevent exposure to sunlight and UV damage.
Boat season will be back before we know it, and with good preparation your boat, trailer and tires will be clean, rodent-free and with tires ready to roll.