XD center caps are identified by the cap code in each wheel’s official specification chart — the “Cap” field, matched by exact wheel part number, not by wheel diameter or bore size.
A 20-inch XD wheel and a 17-inch version of the same model can take completely different caps, and one wrong suffix letter means the cap will not seat. The measurement work below exists to confirm what the chart already tells you, or to rebuild the answer when the original cap is gone.
Why Wheel Size And Bore Don’t Decide Cap Fitment
XD publishes wheel-specific data for every model: part number, size, bolt pattern, backspace, offset, bore, load rating, and a separate cap identifier. Those last two fields are not interchangeable.
The XD871 SLASH part XD871MX20903520 is a 20×9 wheel with a 78.10 mm bore and cap XDCAP001MXBSTARSF. The 8×170 version of that same wheel uses XDCAP001MXBSTARSFT — one trailing letter apart, and a different part. The XD811 ROCKSTAR II applications mostly list SC-198, while an 18×9 5×114.3/5×127 fitment carries SC-205. Listed bores across XD wheels run from 72.56 mm to 130.81 mm, and bore size alone never predicted which cap was listed.
Some wheels carry no decorative cap at all. XD001 dually inner rear wheels are listed with NONE in the cap field.
What To Measure With The Wheel Off
Pull the wheel and measure the cap and its opening directly — the only way to confirm a fitment when the part number is unknown.
- Cap outside diameter: digital calipers at the widest cylindrical retaining section, not the decorative face.
- Wheel opening diameter: measured at the retaining ledge inside the bore where the cap locks.
- Insertion depth: how far the cap body travels in before it stops.
- Retaining method: snap-in tabs, threaded fasteners, or a separate decorative insert held by screws or rivets.
- Face diameter and overall depth: enough clearance so the cap never contacts the hub, axle, brake hardware, or lug nuts.
Write every number down before you shop. XD’s FAQ points buyers to its accessory site for replacement caps, cap screws, rivets, and related hardware, but publishes no universal cap size or measuring formula — the per-wheel specification chart is the authority.
Common Mistakes That Cost You A Return
Most failed cap purchases trace back to matching on the wrong number or ignoring a suffix.
Treating wheel diameter as cap size is the first error — 17, 18, 20, and 22 inch wheels share cap families with nothing in common dimensionally. Matching only center bore is the second, since bore describes the wheel’s hub opening, not the cap’s outside diameter. Matching bolt pattern without the exact model, finish, and part number is the third.
Then there’s the suffix trap. XDCAP001MXBSTARSF and XDCAP001MXBSTARSFT look like the same cap and are not. XD849 GRENADE II caps span T167L1335S1-H34 through T167L1708C1-H63 depending on application, and XD842 SNARE uses either 1508S04 or 1508S03 by finish. The XD825 BUCK 25 shows M-1015GB on its 20×9 and 20×10 listings. If you’d rather compare the common replacements side by side before ordering, this roundup of tested XD Series center cap options covers the popular identifiers.
XD’s own center cap and hardware FAQ confirms replacements run through the accessory store by wheel-specific part.
| XD Wheel Model | Listed Cap Identifier | What It Shows |
|---|---|---|
| XD871 SLASH (20×9) | XDCAP001MXBSTARSF | 78.10 mm bore |
| XD871 SLASH (8×170) | XDCAP001MXBSTARSFT | Suffix changes the part |
| XD811 ROCKSTAR II | SC-198 | Most applications |
| XD811 (18×9 5×114.3) | SC-205 | Fitment-specific cap |
| XD842 SNARE | 1508S04 / 1508S03 | Finish-dependent |
| XD825 BUCK 25 | M-1015GB | 20×9 and 20×10 |
| XD001 dually inner rear | NONE | No cap listed |
Safety And Installation Checks
A cap that fits the opening can still be wrong if it interferes with anything behind it.
Remove the wheel or have a tire and wheel technician inspect the internal retaining features — never measure from underneath a vehicle held only by a jack. Use rated jack stands. Do not force a cap into an opening, drill or enlarge the wheel, bend retaining tabs, or install anything that blocks full lug-nut seating. Check clearance at the hub, axle, brakes, and valve hardware before the wheel goes back on.
Confirm the final match by exact XD wheel part number and cap identifier. Center cap fitment says nothing about load rating, offset, or overall wheel compatibility — those are separate specs in the same chart, and they matter just as much.
The short version: find your wheel’s part number, read the Cap field, and let the chart pick the cap. Measure only when the chart can’t answer.
Common Questions
Where do I find my XD wheel part number?
The part number is stamped or cast on the wheel, often on the back of a spoke or near the hub mounting face, and it also appears on your purchase paperwork. XD lists part numbers alongside every model in its specification charts. Read the full number including any letter suffix before you search for a cap.
Can I reuse a cap from a different XD model?
Only if the cap identifier matches. XD’s listings show several distinct cap families — SC-series, T167-series, M-series, and the XDCAP series — with no cross-compatibility stated. A cap that physically drops into the opening may still sit at the wrong depth or block lug hardware. Match the identifier, then verify clearance.
What if my wheel lists NONE in the cap field?
Some applications, including XD001 dually inner rear wheels, carry no decorative center cap from the factory. There is no correct cap part for those positions, and adding one risks interference with the hub or axle hardware. Leave it open or consult a wheel technician before fitting anything.