I believe the factory recommends alignments every 12 months. You can get away with up to 2 years. I used to do it every year and the report sheet showed that it was off very little and still very well within specs. So I decided to do it at 2 years. It doesn't matter if you feel it or not. Sometimes it could be off and you wouldn't even know. Definitely get it done when you change rims. It's better safe than sorry.