Tire rotation and balance are two very important steps in keeping your four wheels rolling properly. Rotating tires at every other oil change will keep your tires wearing properly. Front tires always wear a little faster than rears because you are constantly turning them which causes more stress/wear. Rotating these tires to the rear, and moving the rears to the front will keep all fours of your tires wearing evenly.
Tire balancing is done in house. Rims and tires need to be evenly balanced due to the fact that they are a completely equal circle spinning in one constant direction. If the weight is off on any given part of the rotating rim and tire it can cause a wobble/vibration while driving. Most commonly this happens at certain speeds where the wheel starts to hop from having unbalanced weight in motion. Sometimes this will occur at one speed say 45, and then fade once you reach 50. It causes a discomfort for the vehicle occupants, but can also cause wear on steering/suspension components since it is stressing the parts that the actual wheel bolts on to. Wheel balance can be thrown off by many variants including; Tire Wear, Rust/Corrosion, Pot Holes, Weights Coming Off. Having a set of four tires balanced while they are off of the vehicle for a rotation is never a bad idea.