Steering vibration can be a consequence of your tyres not being balanced correctly. Vibrations usually occur around 30mph and as the speed increases to 60mph.
Keeping your wheels balanced can extend the life of your tyres and suspension and it makes your driving a lot more comfortable.
Please note that not all problems to do with steering vibrations are because of the tyres not being balanced correctly. You can experience similar faults if the tyre has gone out of shape or has been damaged.
Always get your wheels and tyres checked if you experience vibrations.