make sure you don't have too much air in your tires - as it gets hotter outside you need to check that frequently, if the tires are too hard, they can bounce.

also, i'd suggest wheel balancing, but you've done that.

as well, have an alignment done on both your front and back. if the car isn't steering straight, or one wheel is out of alignment, that wheel will "skip" down the road. this will also wear out your tires very quickly. with the condition of many roads here, the high speed of many drivers, and the inexpensiveness of 4 wheel alignment here, should do that once a year anyways as it saves your tires.