I don't know how someone might specify the caps; and I don't know if the 14" & 15" wheels use the same cap.
My Enkei wheels are 15". The threaded center portion measures roughly 2.5" OD across the threads (major diameter). They are a fine pitch thread. Below are pictures of my center cap.
Cap width across flats: 3.0"
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Cap height: .94" (15/16" ?)
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Thread inside dia. (minor pitch dia.): 2.5"
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Looks like a fine pitch to me:
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Enkei is a Japanese company. Maybe they used a metric thread form? Metric threads aren't specified in threads per inch. Instead, they measure the pitch.
Pitch: 1.5 millimeters (as best I can measure) I don't have any thread gages.
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Note: I couldn't get the calipers straight across the threads on the wheel for an accurate measurement. My best attempt was:
62.9 millimeters...safe to call it 63mm major thread diameter.
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So, with that, I'll say the thread form is 63mm (major dia.) x 1.5mm pitch
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Oh yeah, the cap is "secured" in place with a small set screw. The cap is aluminum.
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