The number of lug bolts and the diameter of the circle on which they are arranged. Determines wheel-to-vehicle compatibility.
Bolt pattern (sometimes called pitch circle diameter or PCD) describes the number of lug bolts on a wheel and the diameter of the circle on which they are arranged. The format is typically given as "X x Y" where X is the number of bolts and Y is the circle diameter in millimeters or inches.
Common bolt patterns include 4x100 (used on early Volkswagen, Honda, and many compact cars), 5x100 (Subaru, older Volkswagen), 5x108 (Ford Focus, Volvo), 5x110 (Pontiac G8, some Saab), 5x112 (modern Volkswagen, Audi, Mercedes-Benz), 5x114.3 (Honda, Mazda, Mitsubishi, Toyota, Nissan), 5x115 (Cadillac, Dodge), 5x120 (BMW, Ford, Land Rover), 6x114.3 (Nissan trucks, Toyota Tacoma), and 8x6.5 (heavy duty trucks).
Bolt pattern compatibility is essential for wheel installation. Wheels with the wrong bolt pattern cannot be safely installed. Some vehicles use rare bolt patterns (Chrysler 300C SRT-8 uses 5x115; Ford Mustang uses 5x114.3) that limit aftermarket wheel options. Bolt pattern adapters allow wheels with different bolt patterns to be fitted, but the adapters add weight and reduce reliability; they are not recommended for serious performance applications.