Steering wheel vibrations
Issues involving steering wheel vibration problems are usually most noticeable at two narrow speed ranges (5-10mph and 60-70mph), and will decrease significantly – sometimes even disappear – outside of these ranges. The amount of vibration caused by worn tires will often be seen over a broader speed range if the tire is worn more. The severity of the vibration is directly related to the vehicle’s speed. The speed range at which the vibration is felt is also directly related to the amount of wear the tires have endured. Sometimes, “wobbles” can be felt at low speeds, for example. These are mostly caused by bent wheels, tires with shifted belts (also referred to as “runout”), and suspension/alignment issues.
Tire or Wheel Vibrations
When a belt is broken inside of a tire it will cause the tire to “bounce” since it is unable to keep its form. Think of a tire without a broken belt as a baseball, and the tire with a broken belt as a stress ball.
A slipped belt causes a tire to “wobble,” and the steering wheel to shake.
(out of round, bent, excessive wear, uneven tread, etc)
Usually, neither tires nor wheels are perfect. This is the reason why wheels are balanced whenever tires are replaced, and then rebalanced periodically as they wear. Driving with unbalanced wheels long enough can and will cause flat spots in the tire, which will cause it to constantly vibrate.
Suspension & Alignment
Excessively worn suspension components will effect the way in which the tire contacts the road. This is due to the fact that if any component (ball-joint, tie-rod, wheel bearing, etc) has excessive play, it affects the position because it may make maintaining proper alignment impossible. It may also cause other problems not related to wheel balance and wear.
Bad alignment is the cause of many tread wear problems that will create vibration issues even if the wheels are perfectly balanced.