Don't make assumptions about the effects of imbalanced tires. They do different things under different circumstances. Make sure they're all inflated properly , too.
Rotate the tires front to back , back to front, make sure they're inflated and see if there is any change when you do down the road.. How old are the tires?
Much wisdom is spoken here. I have been down this road before and seen some weird effects that ended up being tires.
A rotation and balance is quick, cheap, and easy.
