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BMW & Mini Center Cap Sizes — One Brand, Two Caps: 57 mm or 68 mm
Ask a parts counter for "a BMW center cap" and you've only finished half the question. BMW — and Mini, which shares the family — run two OE cap sizes: 57 mm and 68 mm, and which one you need is decided by the wheel, not the badge on the hood. Order by model name alone and you have a coin flip's chance of getting a cap that seats.
The 68 mm cap
The larger of the two families measures 68 mm OD and 68 mm ID — face diameter and clip diameter are the same number on this cap, which makes it one of the easier ones to verify with a caliper: measure across the face, then across the clip tips on the back, and both readings should land at 68 mm. If your old cap reads 68 on both sides, you're in this family and can order with confidence.
The 57 mm cap
The smaller family is a 57 mm OE cap, fitted to a different set of wheels. Eleven millimetres is not a tolerance — a 57 mm cap dropped into a 68 mm wheel opening falls straight through the fitment, and a 68 mm cap will never seat in a 57 mm opening no matter how hard you push. There is no "close enough" anywhere in this brand.
Why the split exists
Center caps are designed for wheels, and wheel designs change across generations, diameters and trim packages. BMW has shipped a lot of wheels over the years, and the cap families followed the wheels. This is the same pattern you'll see across this whole site: the vehicle is the starting point, the wheel is the answer. Two identical-looking cars on different factory wheels can take different caps.
Don't let the hub bore vote
A BMW 3 Series wheel centers on a 72.6 mm hub bore (5×120). That number is real — and it matches neither cap family. The bore centers the wheel on the hub; the cap clips into its own opening. Ordering a 72.6 mm "cap" because a fitment chart printed the bore is the single most common wrong-order story in this business, and BMW's numbers make the trap especially easy to fall into because 72.6 sits above both real cap sizes and looks plausible.
Before you buy
Read the back of your old cap first — BMW moldings usually carry a part number, and a number beats a guess every time. Then match OD and clip ID, in that order. If you're shopping marketplaces, search by the size family plus the part number, not by "BMW center cap" alone; the listings that publish full dimensions are the ones worth your money.
Disclosure: this site stocks nothing and sells nothing directly — we earn on referrals, not on parts. Where we mention dealers or marketplaces, any shopping link that becomes an active affiliate link may pay us a small commission at no extra cost to you. That model is exactly why our advice starts with a caliper instead of a checkout button.
Related guides
- How to Read the Part Number Molded on the Back of Your Center Cap
- Mercedes-Benz Center Cap Size — the 74 mm OE Cap
- By Brand — the BMW and Mini entries
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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Sources: DEZENT magazine OE-cap fitment article (dezent-wheels.com) for the 57 mm / 68 mm BMW–Mini split; eBay OEM listing item 158035047292 publishing 68 mm OD / 68 mm ID; hub bore via the opplehouse bolt-pattern / center-bore guide. Sizes published as commonly listed — verify by measuring.