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Center Cap Sizes in Inches vs Millimetres — the Conversion Traps
Center cap sizing is metric — the factories design in millimetres and the calipers read in millimetres. But marketplaces list in inches, and the conversions hide traps. A cap described as "3 inch" is 76.2 mm by arithmetic and is usually Porsche's 76 mm family in fact. A "2.5 inch" Jeep cap quotes the clip diameter, while the same cap's face measures 63–64 mm (about 2.5″ is 63.5 mm — the rounding alone spans the fitment tolerance).
The conversions that actually occur
| Listed as | Exact mm | Usually means |
|---|---|---|
| 2.25″ | 57.2 | Mazda clip ID family (57 mm) / Toyota Corolla 57 mm OD |
| 2.5″ | 63.5 | Jeep 1LB77 clip ID; VW 65 mm OD caps also described nearby — check which diameter is meant |
| 2-5/8″ | 66.7 | Cadillac car caps (OEM 23212548), about 67 mm |
| 2.72″ | 69 | Honda/Acura 44732 family OD, 69 mm |
| 3″ | 76.2 | Porsche 76 mm OD; F-150 2012–2014 snap-in cap (CL3Z1130B) |
| 3.25″ | 82.6 | GM truck 83 mm OD family |
The three traps
- Rounding. 83 mm is 3.27″, listed as 3.25″. Order by the rounded inch figure and a different cap can match the description.
- Which diameter? Inches in a listing may quote the face (OD) or the clips (ID) — 5 mm apart on a Subaru (60/55). The listing rarely says.
- Fractions. 2-5/8″ "about 67 mm" is a conversion, not a measurement. Your cap is one or the other; the caliper knows.
Overall, car cap ODs run roughly 50–80 mm (about 2–3.15″); trucks and lug-cover styles run far larger, up to roughly 180–210 mm. Work in millimetres from the first measurement to the final click and the traps disappear.
Next steps
Run your numbers through the Cap Finder, or re-check them with the How to Measure walkthrough before you order.
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Video: “How To Measure Hubcap Size - What Size are My Hubcaps? - Hubcaps.com” — Hubcaps.com on YouTube →
Related guides
- How to Measure Wheel Center Cap Size (OD, Clip ID, Depth)
- Cadillac Center Caps — 83 mm Trucks, 67 mm Cars
- Jeep Center Cap Sizes — 63–64 mm and the 55 mm Versions
Sources: size families as documented across our brand research (EngineerFix measurement guides; DEZENT OE-cap article; eBay OEM listing item specifics). Conversions are arithmetic. Sizes published as commonly listed — verify by measuring.