Soft tire...

We have had our truck for about 4 months. In that time I have noticed that the left front tire seems to perpetually be a bit soft. Luckily I have air compressors in my garage and can fill the tire up as needed. I am thinking that this spring I will need to take the truck somewhere to have the tire serviced. I don't really want to deal with it right now in snowy weather and would like to wait until spring if at all possible. It likely has a slow leak somewhere in it that needs patching. Hopefully I don't need a new set of tires already.