As you drive your car and it compensates for variations
in the road surface, your tires can go slightly out
of round. This can cause vibrations or pulsations felt
in the steering wheel and can also decrease your ability
to control; especially at higher speeds, sharp turns or
quick stops. Also, as a result of variations in the
weight of your vehicle from front to back and side to
side; as well as road surface variations, each wheel
does not wear at exactly the same rate as the others.
To compensate for these issues, it is recommended that
you rotate your tires every 6,000 miles or every other
oil change and check the balance of your tires at least
once a year. This will extend the life of your tires
and improve your vehicle's handling and, therefor your
ability to control it safely.