A misaligned vehicle can also cause tires to wear unevenly thus changing their balance. 

Driving with tires that are low on air pressure can cause excessive wear on the inside and outside edges of the tires and will affect the balance of the tires.  This will also shorten the life of the tires and affect your gas mileage.  No one likes to drive a car when the steering wheel shakes and the car wants to keep pulling to one side or the other.  This can be very tiring on a longer trip.  These are two of the symptoms that you may feel if your car suffers from either of these concerns.  If you are an average driver, driving 12-15,000 miles a year, consider having the tires rebalanced and the car aligned once a year.  This will insure a smooth ride and less wear and tear on your vehicle.  Check with your technician; many vehicles built today require all four wheels to be aligned.