Pulttijako

Pulttijako is a term used to describe the arrangement of bolts (lug bolts or lug studs) that fasten a wheel to a vehicle hub. It is defined by two main elements: the number of bolts and the pitch circle diameter (PCD), which is the diameter of the circle that passes through the centers of all the bolts. Together these parameters determine whether a wheel can be mounted on a given hub.

The standard notation for pulttijako is N x PCD, where N is the number of bolts and PCD is measured in millimeters. For example, 5x114.3 indicates five bolts arranged on a circle with a diameter of 114.3 mm. In addition to the bolt pattern, a wheel must also match the hub bore size (center bore) to ensure proper centering and fit. If the bore is too large, adapters or centering rings may be used, but these can affect runout and safety if not correctly installed.

Compatibility is essential because wheels with an incompatible pulttijako will not align with the hub holes or studs. Some vehicles share patterns, while others have unique configurations. In practice, choosing wheels requires verifying both the bolt pattern and the hub bore, along with other factors such as wheel offset, width, and load rating. In some cases, adapters exist to convert one pattern to another, but they introduce mechanical compromises and may affect handling and safety.

Common patterns vary by region and vehicle type. Passenger cars often use 4x100, 5x114.3, or 5x112 patterns, while light trucks and SUVs frequently use 6x139.7 or 5x120, among others. Understanding pulttijako helps ensure proper wheel fitment, safety, and optimal performance.