Lead is the deviation of the vehicle from a straight path on a level road, without hand pressure on the steering wheel. Lead is usually the result of one of the following conditions:

1. Tire wear. Refer to Tire Diagnosis - Irregular or Premature Wear in Tires and Wheels.
2. Uneven parking brake adjustment. Refer to Park Brake Cable Service/Adjustment in Brakes.
3. Wheel Alignment

The way in which a tire is built may produce lead. Rear tires do not cause lead.