How to Measure a Trailer Wheel Bolt Pattern (5x4.5 Explained)
A bolt pattern like 5x4.5 means five lug holes on a 4.5-inch circle. Even lug counts measure center-to-center straight across; 5-lug wheels measure from one hole's center to the far edge of the hole two positions over — or use the exact neighbor-spacing method.
Reading the number
5x4.5 (also written 5 on 4½ or 5x114.3 mm): the first number is the lug count, the second is the diameter of the circle the holes sit on.
Measuring it right
- 4, 6 or 8 lugs: measure from the center of one hole to the center of the hole directly across. Done.
- 5 lugs: there's no hole directly across. Shop method: center of one hole → far edge of the hole two positions over. Exact method: measure two neighboring holes center-to-center and multiply by 1.7013.
The bolt pattern guide has diagrams for both and a calculator that names the standard pattern from your neighbor measurement.
Common trailer patterns
| Pattern | Metric | Typically on |
|---|---|---|
| 4x4" | 4x101.6 | small boat/utility trailers |
| 5x4.5" | 5x114.3 | the most common trailer pattern |
| 5x5" | 5x127 | some trailers, classic GM |
| 6x5.5" | 6x139.7 | tandem-axle trailers |
| 8x6.5" | 8x165.1 | heavy tandem/triple axle |
The other fitment number
Bolt pattern gets the wheel on the hub; offset/backspacing decides where it sits. If you're swapping wheel styles, check both — here's the offset ↔ backspacing calculator with a live diagram. Then browse trailer wheels by size and pattern.