If you have to use the spacers, you should get the tires balanced by someone that does it on the car. This will actually balance the entire rotating mass. The tires, wheels, rotors, hubs and also the spacers. What you have to watch out for is to mark the area where the valve stem lines up on the hub and spacer, in case you have to remove the wheel for maintance, you can reinstall it just like it was when it was balanced.