The steering linkage needs lubrication.

Lubricate the steering linkage. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.

The front tire inflation pressure is low.

Inflate the tires to the recommended pressure. Refer to Tire Inflation Description in Tires and Wheels.

The front wheel alignment settings are incorrect.

1. Check the front wheel alignment settings.

Refer to Fastener Tightening Specifications in Wheel Alignment.

2. Align the front suspension as needed. Refer to Front Caster Adjustment or Front Camber Adjustment or Front Toe Adjustment in Wheel Alignment.

The kingpin or the kingpin bearing are worn or loose.

1. Replace any of the worn parts as needed.
2. Adjust the kingpin bearing as needed.

Refer to Steering Knuckle and King Pin Replacement in Front Suspension.