2018 Audi A4 Wheel Interchange

tl;dr

Use the calculator to compare any donor wheels to your 2018 Audi A4. Start from your car’s door-jamb tire placard. Match 5x112, 66.6 mm hub, and M14x1.5 bolts. Keep offset changes small and verify brake and fender clearance before driving.

Recommendation

I build fitments by confirming the baseline, then testing changes. Do this in order:

• Confirm your OEM wheel and tire size on the driver door placard. Audi offered multiple packages in 2018. The data below shows mixed 17 and 18 inch info. Use your placard as the baseline in the calculator.
• Only consider wheels with 5x112 and a center bore of 66.6 mm. Larger bores can use rings. Smaller bores will not fit the hub.
• Thread is M14x1.5. Your A4 uses wheel bolts. Match the correct seat type to your wheels. Check an existing bolt to confirm seat profile.
• In the calculator, set “Installed on” to your A4 and enter your confirmed OEM size. Then compare the donor wheel or a custom size. Watch tire diameter, inner clearance, and poke.
• Keep total tire diameter change small. Many shops target within about 2 percent. Use the speedometer and fender gap outputs for a reality check.
• Keep offset near stock to protect scrub radius and bearing loads. If you widen the wheel, adjust offset to maintain inner clearance first.
• Do a physical test fit before mounting tires. Spin the wheel to check caliper, knuckle, and liner clearance at full lock and compression.

Impact

• Offset: Lower ET pushes the wheel outward. Too low can poke and rub. Higher ET pulls inward and can hit the strut or control arm.
• Width: Wider wheels move both inward and outward from the hub face. The calculator shows inner and outer changes separately. Use that to balance clearance.
• Tire diameter: Larger diameter fills the arch and reduces clearance. Smaller diameter lowers the car and speeds up the speedometer.
• Centering: A 66.6 mm hub makes hub-centric fit easy. Larger-bore wheels need quality rings for smoothness.
• Hardware: Spacers require longer M14x1.5 bolts. Only if needed. Torque to OEM spec from the manual.

Risks

• Mixed OEM data: 2018 A4 trims vary. Do not assume size from photos or listings. Use your door placard and OEM documentation.
• Seat mismatch: Cone-seat bolts in a ball-seat wheel, or vice versa, can loosen. Confirm visually.
• Brake clearance: Many aftermarket designs have thicker spokes. Check barrel and spoke-to-caliper clearance during test fit.
• Rubbing: Aggressive offset or diameter can hit liners over bumps. Load the suspension when checking.
• Vibration: Running lug-centric without rings on a larger bore often causes shake. Use proper hub rings.
• TPMS: Some regions use indirect systems, others direct. Follow your owner’s manual for reset or sensor needs.

Next actions

Known OEM fitment data for 2018 Audi A4

Because Audi offered multiple wheel packages, confirm your exact OEM size on the vehicle placard and in your owner’s manual. Use those as the baseline in the calculator.

Checklist

• Read your door placard for tire size and load index.
• Enter your OEM baseline into the calculator, then compare the donor or custom setup.
• Match 5x112 and 66.6 mm hub. Plan hub rings if the wheel bore is larger.
• Keep tire diameter change minimal. Verify speedometer and clearance in the calculator.
• Confirm bolt seat type and length. Replace hardware as needed.
• Test fit on the car. Check lock-to-lock and through suspension travel.
• Torque wheel bolts to the OEM spec from your manual. Re-torque after 50–100 miles.

Gotchas

• Backspacing differs by wheel width. Do not compare backspacing across different widths without the calculator.
• Spacers fix inner rub but can cause outer poke. Model both sides.
• Some tire models run wider than labeled. Check section width by brand if you are close.

Helpful tools

• 1/2 inch torque wrench
• M14x1.5 wheel hanger guide pin
• 66.6 hub-centric rings

Use the on-page calculator to validate every change before buying. If anything is unclear, cross-check with your owner’s manual and OEM service information.