A bolt pattern reads like "5x114.3": five studs on a 114.3mm circle. That circle — the pitch circle diameter, PCD — is the one number you must get right before buying wheels, and the one number people most often measure wrong on odd stud counts. The fix is a single trig fact: on a 5-lug hub, measure two adjacent studs center-to-center and multiply by 1.7013. Here's the geometry, the conversions, and the fitment factors that matter after the pattern matches.
The first number is the stud count: 4, 5, 6, or 8 on passenger vehicles, 10 on some heavy trucks. The second is the diameter of the circle passing through all stud centers — PCD in millimeters, or inches on older domestic listings. "5x114.3" and "5x4.5" are therefore the same pattern: 4.5 × 25.4 = 114.3, exactly. The wheel industry's inch-metric equivalents are worth taping to the toolbox:
| Inch name | Metric name | Where you'll see it |
|---|---|---|
| 5x4.25 | 5x108 | Various Ford, Volvo |
| 5x4.5 | 5x114.3 | Most Japanese/Korean 5-lug |
| 5x4.75 | 5x120.65 | Long-running GM circle |
| 5x5 | 5x127 | Many Jeep/Dodge/Chrysler |
| 5x5.5 | 5x139.7 | Toyota/Lexus trucks, older domestic trucks |
| 6x4.5 | 6x114.3 | Many Nissan/Isuzu trucks |
| 6x5.5 | 6x139.7 | Dominant truck 6-lug circle |
| 8x6.5 | 8x165.1 | Classic domestic HD trucks |
Easy mode: even counts have studs directly across from each other, so measure center-to-center across two opposite studs and you've measured the PCD itself. A 4x100 hub reads ~100mm across; a 6x139.7 truck hub reads ~139.7mm (5.5"). No math.
Five studs sit 72° apart, so none oppose each other — a straight-across measurement is meaningless. Geometry fills the gap: on any circle, the distance between two adjacent stud centers equals PCD × sin(half the angle). For 5 lug, half-angle is 36° and sin 36° = 0.5878, so:
PCD = adjacent spacing ÷ 0.5878 = adjacent spacing × 1.7013
Worked example with clean numbers: measure 67.2mm between adjacent centers. 67.2 × 1.7013 = 114.3mm = 4.5" — the 5x114.3 (5x4.5) pattern. Measure 82.1mm on another hub: 82.1 × 1.7013 = 139.7mm = 5x5.5, the truck circle. Both check on a calculator, and both are what the bolt pattern calculator returns from those inputs. The factors for other counts: 3-lug ×1.1547, 4-lug ×1.4142, 6-lug ×2 exactly, 8-lug ×2.6131.
Practical tips: measure center-to-center (the edges of the studs mislead), use calipers if the number matters — the close pairs below differ by less than a tape measure's error — and if you get a number between two standards, re-measure before concluding anything.
Studs + one measurement in, matched standard pattern in mm and inches out — plus PCD and backspace-to-offset converters.
Bolt Pattern Calculator →Legitimate dual-pattern wheels exist: manufacturers drill two circles (e.g., 5x114.3/5x115) into one casting, and both are then true fits. That's the safe way to cover close patterns — not tolerance-stacking on the lug nuts.
The bolt circle is one of four checks:
Your authority for all four is the owner's manual and the door-jamb sticker, and any wheel retailer's "fits your car" claim should still be verified against them. While you're under the car, a wheel alignment after new wheels and tires protects the investment — new rubber on the old alignment wears out fast.
Measure center-to-center between two adjacent studs and multiply by 1.7013 (that's 1 divided by sin 36°). A 67.2mm adjacent spacing equals 114.3mm — the 5x114.3 / 5x4.5 pattern. Alternatively, measure from the center of one stud to the outer edge of the stud two away, which approximates the circle diameter directly.
Yes — 4.5 inches × 25.4 = 114.3mm exactly. Metric and decimal-inch names for one circle. The same applies to 5x5 = 5x127, 5x5.5 = 5x139.7, 5x4.75 = 5x120.65, 6x5.5 = 6x139.7, and 8x6.5 = 8x165.1.
They are different circles 0.7mm apart, and the honest answer is no — forcing the combination wedges the lug hardware at an angle, and it's a failure mode tire shops see regularly. Some wheel makers drill dual patterns (5x114.3/5x115) into one wheel; that's the legitimate way to cover both.
The owner's manual lists it, the driver's door-jamb sticker usually references wheel/tire fitment details, and a dealer parts desk can confirm by VIN. Measuring takes two minutes with calipers, so most people verify rather than trust memory — pattern databases online are frequently wrong on close pairs like 120 vs 120.65.