Even a Hunter Road Force machine can't make up for bad tires and/or wheels. If either are out of round or out of balance, you can be out of luck. If the tech knows his stuff, he'll show you the balance and thrust sheet to show how he's cancelling the thrust tendancies of each wheel/tire combo. But, if there's a lot of thrust or out of round present he probably can't get it perfect. He should advise you of that so that you can replace the poorly constructed tire with a better one.