Odd front end feeling

2001 cavalier well maintained. Here is the problem, there is a cyclical rotating feeling that can be felt in the floor pan of my car. It is difficult to explain there is no sound, but a slight kind of out of balance, almost like when there is a rock stuck in your tread feeling. There is no vibration in the steering wheel. The front tires are new and balanced. The problem is most noticable around 25-35 mph and doesnt get worse with speed> dont really notice it at all at highway speeds. I jacked the car up and there is no play in the wheel, top bottom or left right. Clutch in or out makes no difference and turning does no affect the feeling. Car tracks down the road strainght, doesnt pull and stops in a straight line no fading left or right??? any help would be appreciated.