OEM wheel and tire fitment specs for the 2018 Audi S8, including bolt pattern (PCD), center bore diameter, thread size, rim diameter, rim width, wheel offset, and backspacing.
Recorded OEM specifications for the 2018 Audi S8, donor years with overlapping ranges, and a calculator to compare a selected wheel. Range overlap is not a guaranteed fit.
Center-bore records disagree: year-level hub 66.6 mm vs trim range 66.5–66.5 mm. Interchange below does not treat this as an unqualified match.
Thread-only product links are shopping examples, not verified fits. Seat style is not confirmed here. As an Amazon Associate we earn from qualifying purchases.
Donor vehicles with overlapping OEM specs
These are vehicle-year records whose recorded OEM ranges overlap this 2018 Audi S8. Overlap is not a guarantee that a specific wheel will install. Selected-wheel comparison is in the calculator below.
Evaluated 188 donor years. Listed 24 eligible overlaps (not all evaluated years are compatible). Showing all listed.
Wheel geometryOEM width/offset ranges overlap (not a specific wheel)
Center-bore records disagree (target year-level hub 66.6 mm vs trim range 66.5–66.5 mm; donor year-level hub 66.6 mm vs trim range 66.5–66.5 mm). Unqualified overlap is not claimed until the conflict is resolved.
Wheel geometryOEM width/offset ranges overlap (not a specific wheel)
Center-bore records disagree (target year-level hub 66.6 mm vs trim range 66.5–66.5 mm; donor year-level hub 66.6 mm vs trim range 66.5–66.5 mm). Unqualified overlap is not claimed until the conflict is resolved. Width/offset ranges overlap; confirm diameter and brake clearance for your trim.
Audi S8 Years With Compatible Wheels
Only years with evidence-based interchange relationships are listed. Adjacent years are not assumed compatible.
Compare a donor vehicle or custom wheel against this 2018 Audi S8. Use Compare in calculator on a donor row above to fill the donor side of this same calculator.
Compare
Compare wheel compatibility between two vehicles
Wheels from (donor vehicle)
Selected Car:
Custom wheel size (optional)
Tip: change values here to simulate custom wheels and immediately see the impact in the comparison below.
Custom tire size (optional)
Installed on (your vehicle)
Selected Car:
2018 Audi S8
Compare Rims
Specification
Wheels from
Installed on
Result (Click it)
Bolt Pattern
The total number of bolt holes and the diameter of the circle they form.
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5x112
Center Bore
The hole in the center of the wheel that fits over the vehicle’s hub.
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66.5 mm
Thread Size
The size and spacing of the threads on the bolts or nuts that hold the wheel in place.
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M14 x 1.5
Rim Diameter
The wheel diameter in inches that determines which tire sizes will fit.
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21"
Rim Width
The distance between the inner edges of the wheel is measured in inches.
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9.0"
Wheel Offset
How far the wheel sits inward or outward relative to the hub mounting surface.
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35 mm
Backspacing
Shows how much space the wheel takes up toward the inside of the vehicle.
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-
Wheel Fasteners
The type of hardware used to secure the wheel to the vehicle.
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-
Compare Tires
Specification
Wheels from
Installed on
Result (Click it)
Section Width
The width of the tire from sidewall to sidewall, measured in millimeters.
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Aspect Ratio
The height of the tire’s sidewall expressed as a percentage of its width.
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Diameter
The wheel diameter for which the tire is designed to fit.
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Tire Pressure
The recommended air pressure for safe and efficient driving.
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Overall Diameter
The total height of the tire and wheel combined affects clearance and speedometer accuracy.
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-
Wheel Fitment Parts for the 2018 Audi S8
Example products matched to recorded thread, hub, or spacer dimensions. They are not verified fits. Confirm seat style, thickness, and clearance before ordering.
As an Amazon Associate we earn from qualifying purchases. Product availability and pricing may change.
2018 Audi S8 wheel fitment guide
tl;dr
OEM baseline: 21x9.0 ET35 wheel with 275/35R21 tire.
Bolt pattern: 5x112. Center bore: 66.6 mm. Thread: M14 x 1.5.
Backspacing listed: 5.88 in. Measure yours to confirm.
Set “Installed on” to 2018 Audi S8 in the calculator, then compare donor or custom sizes before you buy.
Avoid guessing. Confirm in your owner’s manual, door jamb label, or with an Audi parts desk.
Recommendation
Start from the OEM envelope. Keep wheel width, offset, and tire diameter close to factory to preserve clearance, handling, and speedometer accuracy. Use hub-centric wheels or quality hub-centric rings sized to 66.6 mm. Match fastener thread to M14 x 1.5. If a wheel’s center bore is larger than 66.6 mm, rings are required. If it is smaller, the wheel will not seat.
Use the on-page calculator. Set “Installed on (your vehicle)” to 2018 Audi S8. Enter either a donor vehicle wheel or a custom size. Review inner clearance to the suspension and brakes, outer “poke” relative to the fender, and tire diameter change. Large S8 brakes need generous spoke and barrel clearance. If you are considering spacers for caliper clearance, ensure they are hub-centric and that hardware length matches any spacer thickness.
Impact of changes
Offset: More positive offset moves the wheel inward. Less positive moves it outward. The calculator will show inner clearance and poke changes.
Width: Wider wheels grow inward and outward from the centerline. Check both sides for contact risk.
Tire size: Changing section width or aspect ratio alters overall diameter. The calculator updates tire diameter and shows the difference vs OEM.
Center bore and hub fit: Anything smaller than 66.6 mm will not fit the hub. Larger needs rings to stay vibration free.
Hardware: The thread must be M14 x 1.5. Seat style can vary by wheel brand. Confirm with the wheel supplier.
Risks and gotchas
Brake clearance: The S8 has large front calipers. Test spoke and barrel clearance before final mounting.
Fender and liner rub: Check at full lock and during suspension compression. Air suspension changes ride height. Recheck at your lowest setting.
Load rating: Wheels and tires must meet or exceed vehicle load. Low ratings lead to failures.
TPMS: Sensor type and frequency may vary by market or trim. Inspect your current wheels and confirm with OEM documentation.
Spacers: Only use hub-centric spacers with correct hub and wheel bores. Hardware length must suit the spacer. Poor setup can cause vibration or loss of clamping force.
Backspacing variance: Published backspacing can differ from measured due to lip design. Measure if you are close on inner clearance.
Torque: Follow Audi’s specified torque and recheck after a short driving period. Do not guess values.
Alignment: Any fitment change can affect alignment needs. Plan for an alignment after installation.
OEM fitment reference
Spec
2018 Audi S8
Bolt pattern
5x112
Center bore
66.6 mm
Thread size
M14 x 1.5
Rim diameter
21 in
Rim width
9.0 in
Wheel offset (ET)
35 mm
Backspacing
5.88 in
Tire size
275/35R21
If your car differs, it may be due to regional packages, brakes, or dealer-installed options. Confirm by VIN with an Audi parts department or your owner’s manual.
How to use the wheelinterchange.com calculator
Set “Installed on (your vehicle)” to 2018 Audi S8.
Enter the wheel and tire you plan to use under “Custom wheel size” and “Custom tire size.”
Optionally choose a “Wheels from (donor vehicle)” to compare stock-to-stock.
Review inner clearance and poke changes. Verify tire diameter difference is acceptable for you.
If any clearance looks tight, measure the car. Check caliper-to-spoke and barrel gaps physically during a test fit.
Next actions
Checklist
Confirm OEM specs in your manual or door jamb label.
Compare planned sizes in the calculator with “Installed on: 2018 Audi S8.”
Verify center bore 66.6 mm hub fit and M14 x 1.5 hardware compatibility.
Plan for TPMS transfer or programming if needed.
Test fit front first. Check caliper, barrel, and fender clearance at full lock and through suspension travel.
Torque to Audi spec using a calibrated wrench. Recheck after initial miles.
Schedule an alignment if you changed width, offset, or diameter.
A normal wheel spacer does not change bolt pattern. Hub rings cannot enlarge a wheel bore that is smaller than the hub. Brake clearance and tire package fitment still require vehicle-specific checks when not confirmed in the dataset.
