2014 Audi S8 Wheel Interchange

2014 Audi S8 Wheel Fitment Guide

Starting point

I approach the 2014 Audi S8 in stages, because that keeps things clear and safe. Think of it as a mental model that starts with the hard specs, builds a small win with a quick check, then expands into wheels, tires, and offsets using the on-page calculator. I have learned that this sequence avoids the common pitfalls that cause rubbing, vibration, or hardware mismatches.

Small win: lock in the core mounting specs

These are the anchor points I confirm first on every S8 I see. They do not change with wheel style and they control whether a wheel can bolt up and center correctly.

Rule of thumb: the wheel must have a 5x112 bolt pattern and at least a 66.6 mm center bore. If the new wheel’s bore is larger than 66.6, I use hubcentric rings to match 66.6 mm so the wheel self-centers on the hub. Threads are M14 x 1.5 on the S8. Lug seat type and torque can vary by wheel, so I verify those with the owner’s manual or an OEM parts source.

• Helpful tools: 66.6 hubcentric rings, M14x1.5 wheel bolts, 1/2 inch torque wrench, tire pressure gauge

Expand scope: wheels, tires, and the calculator

On this page, the known OEM wheel is listed as 21 x 9.0 ET35, while the known tire example is 265/40R20. That mismatch can happen when multiple factory packages exist or when sources report different trims. I treat it as a flag to verify before buying. A quick path is to check your driver door jamb label and the owner’s manual for the tire listing on your specific car. Then I use the on-page calculator to test both 20 inch and 21 inch cases.

How I run the calculator step by step:

• Set Installed on (your vehicle) to the 2014 Audi S8, using the known specs above.
• If you are considering OEM-size 21 inch wheels, set Custom wheel size to 21 x 9.0 with ET35 as a baseline.
• If you are investigating 20 inch tires, add a 265/40R20 under Custom tire size and let the calculator update total diameter.
• If you are comparing a donor wheel, enter that under Wheels from (donor vehicle) and watch the changes in inner clearance and outer poke.

Think of it as a visual way to see what changes when you alter diameter, width, and offset. The calculator makes it easy to compare a donor wheel to your S8 baseline so you can predict clearance near struts, control arms, and fenders.

Refine: offsets, backspacing, and practical limits

My mental model for fitment on the S8 is simple. Offset moves the wheel laterally, width spreads that change to both sides, and tire size affects overall diameter and sidewall shape. I use these rules of thumb while watching the calculator:

• Offset changes: 1 mm of offset moves the wheel about 1 mm. Lower ET pushes the wheel outward, higher ET pulls it inward.
• Width changes: adding 0.5 in of width increases inner and outer edges by roughly 6.35 mm each, before offset adjustments.
• Overall tire diameter: I try to keep diameter changes modest so speedometer and ride height stay sensible. Around 1 to 2 percent from your verified OEM tire is a practical target in most cases.
• Backspacing: the listed backspacing is 5.88 in for the 21 x 9.0 ET35 baseline. If a new spec increases backspacing too much, inner clearance becomes the limiting factor. If it decreases too much, poke and fender contact can be the limit.

Hardware details that I confirm every time:

• Hubcentric fit: wheel bore 66.6 mm, or larger with correct rings to 66.6 mm.
• Lug seat type: Audi OE wheels often use a different seat profile than many aftermarket wheels. I match the bolt seat to the wheel vendor’s spec.
• Bolt length: if spacers are used, I measure engaged thread depth and select appropriate longer M14 x 1.5 bolts. Hubcentric spacers are my preference for vibration control.
• TPMS: configurations vary by region and build. I confirm sensor type and frequency for the VIN before ordering.

Validate: test-fit and confirm with OEM sources

Before I call a setup final, I validate it three ways. First, I confirm tire and wheel listings using your door jamb label and the owner’s manual. If there is any doubt, I cross-check with an Audi dealer parts department using your VIN. Second, I use the calculator to compare your intended setup to the known S8 baseline and I note inner clearance and outer poke changes. Third, I do a careful test-fit.

My test-fit process on an S8 goes like this:

• Hand-thread bolts and seat the wheel fully against the hub. Confirm hubcentric ring fit if used.
• Torque in a star pattern to the spec in your owner’s manual. Recheck torque after 50 to 100 miles.
• Turn lock to lock and compress the suspension over a gentle ramp to check inner and outer clearance under load.
• Verify that the wheel spins freely without touching calipers, knuckles, or liners.

If anything looks borderline in the calculator, I address it before road use. Small offset adjustments or a slightly different tire profile can resolve light contact without compromising ride quality.

Summary: clear next steps

Quick recap. Your 2014 Audi S8 uses 5x112 with a 66.6 mm center bore and M14 x 1.5 threads. A known OEM wheel is 21 x 9.0 ET35 with 5.88 in backspacing. A known tire example here is 265/40R20. Since that suggests multiple factory configurations, verify your exact OEM tire size on the driver door label or manual, then use the on-page calculator to compare your target setup against the S8 baseline. Watch inner clearance, outer poke, and overall diameter. Match hub bore with 66.6 rings when needed, confirm lug seat type with the wheel vendor or Audi documentation, and torque to the spec in your manual.

This step-by-step flow has kept my S8 fitments predictable and drama free. If you keep the calculator as your guide and confirm the few OEM details that can vary, you will move from exploratory to resolved with confidence.