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Center Bore vs Center Cap Diameter — the #1 Fitment Mistake
Two numbers live at the center of your wheel, and the internet constantly swaps them. Mixing them up is — by a wide margin — the most common reason a replacement center cap doesn't fit.
The two numbers, defined
- Hub center bore — the machined hole in the wheel that centers it on the vehicle's hub. It's a wheel-to-vehicle fitment spec.
- Center cap diameter — the size of the cap: its outer diameter across the face, and more importantly its clip diameter on the back, which must match the opening the cap snaps into.
Related? Yes — they live in the same neighbourhood. Interchangeable? Never. The cap opening and the hub bore are different features, often different sizes, on the same wheel.
Proof, from real trucks
- GM 1500 trucks: hub bore 78.1 mm — but the common OEM cap for 2014–2024 trucks is 83 mm OD. If bore and cap size were the same number, one of these would have to be wrong. Both are right.
- Ford F-150 (2004+): hub bore 87.1 mm — while its caps are a 3-inch snap-in on some wheels and a 180 mm lug-cover on older trucks. The bore tells you nothing about which cap you need.
- Jeep (5×127): hub bore 71.5–71.6 mm — while common Jeep caps measure 63–64 mm OD. Again: different numbers, both correct.
How this mistake shows up in listings
Marketplace listings blur the two constantly, and sometimes a published "cap size" is really a bore figure in disguise. Our own research log has a case study: an aftermarket page claims 64 mm caps for the Mazda 3/6/CX-5, yet OEM part-number evidence (cap BBM2-37-190, 57 mm clip ID) puts the real cap in the 56–57 mm family — the 64 mm figure appears to be a bore-side number that wandered into a cap listing. We publish the OEM-evidenced size and disclose the conflict, which is what any honest chart should do.
Measure your cap the right way: How to Measure Wheel Center Cap Size (OD, Clip ID, Depth).
Related guides
- How to Measure Wheel Center Cap Size
- Chevy Silverado & GMC Sierra — the 83 mm OEM caps
- Fitment Guide — bore table beside cap chart, kept separate on purpose
Next steps
Run your numbers through the Cap Finder, or re-check them with the How to Measure walkthrough before you order.
Shop this fitment on eBay Cap Concierge — we find your cap
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Sources: hub bore data — nupi.nl wheel guide (GM 78.1 mm, Ford 87.1 mm), Enkei wheel catalog via doczz.net (Jeep 71.5–71.6 mm), opplehouse bore guide; cap sizes — eBay OEM listings for GM 22837060 and Jeep 1LB77 family; Mazda conflict documented in our RESEARCH.md from accio.com and OEM part listings.