Which component directly affects how vertical tires are relative to the road surface?

The camber angle is the component that directly affects how vertical the tires are in relation to the road surface. Camber refers to the angle formed between the vertical axis of the wheel and the vertical axis of the vehicle when viewed from the front or rear. The camber angle can be either positive or negative; positive camber tilts the top of the tire away from the vehicle, while negative camber tilts the top of the tire toward the vehicle.

Correct camber settings are crucial for maximizing tire contact with the road during cornering, improving handling, and promoting even tire wear. If the camber angle is not within the specified range, it can lead to uneven tire wear and reduced traction, especially when turning. This makes camber a vital adjustment in suspension alignment to ensure that tires maintain optimal contact with the road surface through various driving conditions.

The other angles, such as toe, SAI (Steering Axis Inclination), and caster, while important for different aspects of vehicle dynamics and handling, primarily influence steering responsiveness and stability rather than the vertical alignment of the tire relative to the road surface.