Center Cap Size Guide: How to Measure for the Right Fit
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Center Cap Size Guide: How to Measure for the Right Fit
Ordering the wrong size center cap is one of the most common mistakes wheel owners make. The good news: it's completely avoidable if you know what to measure. This guide walks you through exactly how to measure your wheel for the right center cap fit — even if you don't have the original cap or part number.
The Two Key Measurements
To find the right center cap, you need two measurements:
- Center bore diameter — The inner diameter of the circular opening in the wheel face where the cap sits.
- Snap ring depth — How deep the retention groove is inside the bore (for snap-in caps only).
In most cases, the center bore diameter alone is enough to narrow down your options significantly.
How to Measure Center Bore Diameter
You'll need a caliper for the most accurate measurement, though a ruler can work in a pinch.
- Remove the wheel from the vehicle — This makes measurement much easier and more accurate.
- Look at the center of the wheel face — You'll see a circular opening. This is the center bore.
- Measure the inner diameter — Place your caliper across the widest point of the opening and measure in millimeters. Take two measurements at 90° to each other and average them if they differ slightly.
- Round to the nearest standard size — Center cap bores are manufactured in standard sizes. If your measurement is 82.5mm, the cap is likely an 83mm bore.
Common Center Cap Bore Sizes
| Bore Size | Common Applications |
|---|---|
| 57mm | Many passenger car OEM wheels |
| 71mm | European vehicles, some import trucks |
| 78mm | Light trucks, some American Racing models |
| 83mm | KMC, Moto Metal, many off-road wheels |
| 108mm | Larger truck/SUV wheels, some Vision models |
| 133mm | Heavy-duty off-road wheels |
Hub-Centric vs. Lug-Centric Wheels
This distinction matters for cap fitment:
- Hub-centric wheels — The center bore of the wheel matches the hub diameter of the vehicle exactly. The cap sits flush and tight.
- Lug-centric wheels — The center bore is larger than the hub. A hub ring fills the gap. The cap still fits the bore opening, but the bore may be larger than expected.
If your wheel uses hub rings, measure the bore opening (not the hub ring) when sizing your cap.
What If My Cap Still Doesn't Fit?
If you've measured correctly and the cap still won't seat:
- Check the retention ring depth — some caps have a deeper snap ring that requires a specific bore depth.
- Verify the cap type — snap-in caps won't work in a bore designed for bolt-on caps.
- Check for debris — even a small amount of dirt in the bore groove can prevent seating.