What Are Bolt Patterns?

Car Rim Bolts

• When installing customized rims on a car, car enthusiasts must decide what kind of rim pattern they want. This is a pattern created by the lug nuts on the rim of the car. The bolts are what hold the rim on the car and are removed when the car owner needs to remove the rim, especially to change a tire. The bolts on the rims can range in number from four to eight. Different rims have different bolt patterns.

Bolt Pattern Gauge

• Some car owners can get their hands on a bolt pattern gauge, a tool that measures the kind of pattern that the customized rims should have. Five-bolt patterns are very hard to measure without using this tool, since the technician would otherwise have to measure the diameter of the circle passing through the center of each of the holes.

Millimeter Distance

• The bolt pattern is measured in terms of millimeters, and the millimeters indicate how far each bolt is from the other bolts. Therange can be from 5 to 115 millimeters. Some cars have two different bolt patterns on the same wheel.

Offsets

• All wheels have offsets, which are the space between the surface of the wheel and the center line of the rim. Positive offsets bring the wheel of the car closer to the fender, while negative offsets tilt the wheel away from the vehicle.

Wheel Size

• Bolt patterns can be designed to plus-size the wheels to enhance the wheel performance. Technicians want to keep the overall tire diameter within 3 percent of the original tire size, because tires that get any larger can reduce the fuel mileage. Changes in the wheel size can affect the bolt pattern that the car owner must have.

Bolt Circle Diameter

• The bolt circle diameter is the size of the circle that the bolt pattern makes. When a rim has more bolts than another rim of the same diameter, the space between each bolt must be smaller for all of the bolts to fit within the diameter.