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Common wheel bolt patterns
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Drilling the pattern
Hole coordinates on a pitch circle for drilling, milling and CNC, with the distance between holes to check with calipers. Measure an unknown wheel bolt pattern, check edge distance and ligament, and copy ready G-code.
| Hole | Angle | X | Y | Polar |
|---|
The holes sit on a circle of diameter D, equally spaced by 360° / n. Each coordinate is measured from the center of the pattern, plus your center offset.
Measuring a 5-stud wheel: you cannot measure straight across, so measure from the center of one stud to the center of the next, or from the back edge of one stud to the center of the one two places away (that is D · sin 72° = 0.951 D). For 4, 6 and 8 holes the pattern is simply the distance between opposite studs. Keep at least 1.5 × the hole diameter between hole centers and about 1 × the hole diameter from the hole edge to the outside of the flange.
This calculator lays out holes equally spaced on a pitch circle diameter (PCD), also called a bolt circle. Enter the circle diameter, the number of holes and the start angle, and it returns the angle and X/Y coordinates of every hole, the hole-to-hole spacing, the distance across the pattern, the ligament and edge distances, and a ready G-code drilling cycle. It can also work backward from a measured stud spacing. Machinists, CNC programmers, designers and car owners checking wheel bolt patterns use it.
Program the five X/Y positions above from the hub center and check the work with calipers: adjacent holes should be 65.83 mm apart center to center. The 12 mm edge distance is just under one hole diameter, so a slightly larger flange would be stronger.
Each hole is at angle θk = θ0 + k × 360° / n, where n is the number of holes, θ0 is the start angle and k runs from 0 to n − 1. The coordinates are X = Xc + (D/2) · cos θk and Y = Yc + (D/2) · sin θk, where D is the bolt circle diameter and (Xc, Yc) is the center. For 6 holes on a 100 mm circle starting at 0°, the holes are at (50, 0), (25, 43.301), (−25, 43.301), (−50, 0), (−25, −43.301) and (25, −43.301).
A 5-lug pattern has no stud directly opposite another, so you cannot measure straight across. Measure center to center between two adjacent studs and divide by sin 36°, which is the same as multiplying by 1.701. A spacing of 65.8 mm gives a 112 mm PCD, and 67.2 mm gives 114.3 mm (4.5 in). Another method is to measure from the back edge of one stud to the center of the second stud over, which equals about 0.951 × PCD.
If c is the center-to-center distance between two adjacent holes and n is the number of holes, then PCD = c / sin(180° / n). For 4 holes, that is c × 1.414. For 5 holes, it is c × 1.701. For 6 holes, it is c × 2.0, and for 8 holes it is c × 2.613. With an even number of holes, you can also measure center to center between two opposite holes, which equals the PCD directly.
The first number is the number of studs or bolt holes, and the second is the pitch circle diameter in millimeters, measured through the hole centers. So 5×114.3 means five studs on a 114.3 mm circle, which is the same pattern as 5×4.5 in. Two wheels with the same pattern may still not interchange, because the center bore, offset, stud thread and seat type must also match.
For equally spaced holes, the angle between neighbors is 360° divided by the number of holes: 90° for 4 holes, 72° for 5, 60° for 6 and 45° for 8. The center-to-center distance between neighbors is the chord c = PCD × sin(180° / n). Where the first hole is placed (the start angle) is a design choice. It is often 0° or set to straddle the vertical or horizontal centerline.
A common guideline is a center-to-center distance of at least 1.5 times the hole diameter, so the web between holes stays strong and the drill does not wander into the next hole. Allow at least 3 bolt diameters where a wrench or socket must fit. From the hole edge to the outside of the flange, leave at least one hole diameter. The ligament is the chord spacing minus the hole diameter.