All newly mounted wheels must be balanced to ensure that there is an even distribution of weight across all the wheels on a vehicle. If the wheel balance isn't quite right you may experience vibration of the steering wheel, faster/uneven tread wear and even poor fuel economy. We would suggest getting your wheels balanced regularly because simple things like cornering and bumps can affect the balance of your front two wheels.
The purpose of wheel balancing is to get your wheels rotating smoothly by ensuring that all areas of the wheel & tyre unit are equal in weight. We do this by adding little balancing weights to the rim of the wheel to balance out any inconsistencies.