Which alignment angle measures the forward or rearward tilt of the steering axis?

The alignment angle that measures the forward or rearward tilt of the steering axis is caster. Caster is crucial for vehicle stability during straight-line driving and cornering, as it affects the driver's steering input and the vehicle's handling characteristics. When the steering axis is tilted forward (positive caster), it tends to give the vehicle a more stable feeling and assists in self-centering the steering. Conversely, a rearward tilt (negative caster) can lead to less stability and difficulty in steering. Understanding caster is essential for diagnosing and resolving issues related to vehicle handling and performance.