To understand wheel bolt patterns, determine the bolt circle diameter and add the number of lug nuts. For instance, if the bolt circle diameter is 3.5 inches and there are six lug nuts, the wheel bolt pattern is 6 by 3.5.
The wheel bolt pattern is the numerical value of the wheel lug holes and the intervals between them. Determining the bolt circle diameter is the first step in understanding the wheel bolt pattern. The diameter can be determined using a bolt pattern gauge or a tape measure. The former is easier to use and ideal when determining the bolt circle diameters of a large number of wheels, because it saves time.
To use a tape measure, start by detaching the wheel from the vehicle and laying it flat on the ground. Stretch the tape from the center of one of the studs to the center of the opposite stud across the wheel. For instance, if the wheel has six studs, the third stud over is the opposite stud, whereas if the wheel features four or five studs, the opposite stud is the second one over. Be sure to use a tape measure that contains both inch and millimeter scales in order to get the bolt circle diameter in the appropriate units.