A vibration is felt in the steering wheel at speeds above 30 mph. What could be the cause?

When a vibration is felt in the steering wheel at speeds above 30 mph, the most likely cause is that the front wheels are out of balance. This is because the steering wheel is directly influenced by the front tires, which are responsible for steering the vehicle. An imbalance in the front wheels can result from uneven tire wear, improper tire inflation, or if weights used to balance the tires have come loose or fallen off. As the vehicle accelerates, the vibration from the imbalanced wheels becomes more pronounced, making it noticeable in the steering wheel.

The other factors do not directly contribute to the specific symptom of a steering wheel vibration. While unbalanced rear wheels can cause vibrations, they typically manifest as vibrations felt in the seat rather than the steering wheel, since the rear wheels do not influence steering directly. Similarly, issues with caster and camber affect wheel alignment and handling characteristics rather than causing vibrations, particularly in the steering wheel. Caster impacts steering stability and feel, while camber affects tire wear and traction but would not specifically cause a vibration in the steering at higher speeds.