The specification refers to the dimensions of the fasteners used to secure a wheel to a vehicle’s hub. This measurement is typically expressed in millimeters (mm) and includes the thread size, pitch, and head size. As an example, a specification might be 12mm x 1.5, indicating a 12mm diameter with a 1.5mm thread pitch.
Correctly identifying this specification is crucial for vehicle safety and maintenance. Employing the wrong size can lead to wheel detachment, resulting in accidents and potential damage. Furthermore, understanding the correct specification allows for proper torque application, preventing over-tightening and potential damage to the wheel studs or the wheel itself. Historically, these specifications have evolved alongside automotive engineering to accommodate increasing vehicle weight and performance demands.