Vehicle Wheel Mechanics and Steering System Components

Vehicle Wheel Functions and Nomenclature

Item 10: The wheel has the mission of supporting the vehicle, transmitting engine power, and ensuring that steering and brakes control the vehicle.

Understanding Tire Specifications

Nomenclature for controlling the wheels (e.g., 175 / 70 R13 82T tubeless):

• 175: Section of the tire in mm.
• 70: The percentage ratio between the tire height and section width.
• R: Radial casing.
• 13: Measurement between the seats (heels) in inches.
• 82: Load index (kg) according to the table.
• T: Maximum speed limit (homologation) according to the table.

Tire Performance and Wear Factors

Features of pneumatic tires:

• Kilometric performance: This refers to the mileage of the tires until their replacement. It is considered to have reached its wear limit when it reaches 1.6mm.
• Specific performance: This is the ratio between the mileage and the millimeter of the rolling tread consumed.
• Evolution of wear: Wear occurs during every kilometer the tire runs. Wear is faster at the beginning and the tire becomes more rigid as it becomes worn.

Factors influencing the life of tires: Inflation pressure, load conditions, speed, driving habits, type and condition of the pavement, ambient weather conditions, and mechanical conditions of the vehicle.

Effects of Tire Pressure

Effects of excess pressure: Reduction of the footprint of the tread, poor flexibility, wear more pronounced in the central part, and loss of adhesion.

Effects of lack of pressure: Excessive flexibility, more crushing, more pronounced wear on the sides, loss of adhesion, and increased fuel consumption.

Wheel Abnormalities and Imbalances

• Warping: Deformation of the wheel caused by tire hits, uneven tightening of the wheel fixing screws, or faulty installation of the tire on the rim.
• Eccentricity: Caused by unequal tire wear, faulty installation, or unequal tightening of the rim.
• Wheel imbalances: Caused by an unequal distribution of centrifugal forces. This results from non-uniform mass about the axis of the wheel, radial or lateral tire deformation, or defective tire repairs.

Slip angle (Deriva angle): The angle formed by the axis of the theoretical direction of the wheel and the axis of the actual path of the tire. It depends on the load, lateral force, inflation pressure, tire width, speed, and driving style.

Steering System Components and Safety

Item 11: The steering system is formed together with a steering wheel and column. Its mission is to direct the orientation of the wheels so the vehicle goes where we indicate.

Elements of the Steering System

• Steering wheel
• Steering column
• Steering box
• Command linkage (timoneria)
• Wheels

The Steering Column

The column connects the steering wheel with the steering mechanism and has a large influence on safety. It is a retractable steering component, typically formed by 2 or 3 sections.

Steering Geometry

Steering geometry is essential for vehicle stability and control.