I'm new to this so keep this mind.
I first checked for anyway rodents could get in and blocked them off. Cover trailer and wheels. I always park on wood to keep tires from freezing to ground or sinking in soft ground.
I use the PVC pipe to build T. Buying rodent poison from Tractor Supply with the hole in it. Set T between and behind duel wheels. Using coat hanger I bend a little hook on one end. Slide three or four baits over coat hanger and slide it down into T. This way if they eat one off another one slides into place. Mice do not have to go any further to find something to eat that also does them in out side of trailer.
Tires I change every five years no matter what they look like. Get date made off side wall. Mine are do for change till next year and will do so early in the season. I am running ST'S but thinking of going to LT's but that is a whole other topic.