2009 Audi S5 Wheel Interchange

1. Starting point

I have set up wheel and tire packages on several B8-chassis Audis, including the 2009 S5, and the same mental model keeps helping me avoid rubbing, vibration, and surprise warning lights. Think of it as a stepwise fitment journey. We begin with what is known, then test small changes in the calculator, then widen the scope to how width and offset reshape clearance, and finally validate on the car before buying anything expensive.

For your 2009 Audi S5, here is the on-page quick recap of the OEM-related data provided for this page. Some values can vary by trim or package, and the tire size shown points to an 18 inch setup while the wheel row lists a 20 inch dimension. That mismatch often means the data is coming from more than one factory configuration. Use the calculator and your door placard to confirm your exact baseline before ordering.

Because the tire line shows R18 while the wheel row shows 20x9 ET29, plan on verifying which factory wheel and tire your car actually has. I have found the door jamb placard and the OEM wheel part number inside the spoke to be the fastest confirmations.

2. Small win

My first quick win is to lock in the baseline using the on-page calculator. Select Installed on as 2009 Audi S5. If your current wheel and tire match the 20x9 ET29 entry above, enter those. If your door placard or your current tire reads 245/40R18, set the calculator to 18 inch and that tire. That gives you a clean reference for all comparisons.

• Use “Installed on (your vehicle)” for your S5 baseline.
• If your current tire shows 245/40R18, set that tire. If your wheel is 20x9 ET29, enter those dimensions.
• Save this state in a browser tab so you can jump back if you get lost.

Rule of thumb I use here: get the stock diameter right first. The calculator will update tire diameter when you change rim diameter, which helps you see ride height and speedometer effects clearly.

3. Expand scope

Once your baseline is in, try small, controlled changes using the calculator’s “Custom wheel size” and “Custom tire size.” Think of it as a safe sandbox. I start with width and offset because they drive inner clearance and outer poke, which are the two places the S5 is most sensitive.

• Width mental model: adding 0.5 inch of wheel width adds about 6.35 mm to both inner and outer sides from the centerline. The car only feels half of a width change per side.
• Offset mental model: increasing offset tucks the wheel inward, decreasing offset pushes the wheel outward.

In the calculator, nudge width by 0.5 inch and offset by 3 to 5 mm to see how inner clearance and outer position shift. Watch the readout for inner clearance to the strut and outer poke toward the fender. On my S5 setups, this is where I caught potential liner rubs before they cost me a tire.

For tires, a common rule of thumb is to keep overall diameter within about 3 percent of stock for speedometer accuracy and fender clearance. Use the “Custom tire size” to try a one-step wider section width and an aspect ratio that keeps diameter close. The calculator will show diameter and sidewall differences in real time.

4. Refine

Now refine the plan around the S5’s hardware. These are the items I check in this order before I purchase wheels.

• Hub fit: the S5 hub bore is 66.6 mm. If a new wheel’s center bore is larger, plan on 66.6 hub-centric rings to keep the wheel centered. If the wheel’s bore is smaller, it will not seat.
• Hardware: your thread spec is M14 x 1.5. Audi uses bolts, not studs from the factory. If the new wheel has a different seat type than OEM, match the bolt seat to the wheel seat.
• Brake caliper clearance: use the calculator to predict inner barrel clearance, then confirm with a physical test fit. I place a small dab of malleable putty on the caliper to measure clearance after mounting hand-tight.
• Backspacing awareness: the listed 5.64 in backspacing corresponds with the example 20x9 ET29. If you change offset or width, backspacing changes too. More backspacing reduces inner clearance.
• TPMS: 2009 S5 equipment can vary by market. If your car uses in-wheel sensors, plan for compatible valves or sensors. If it uses indirect TPMS via ABS, you will reset through the MMI. Check your owner’s manual to confirm which system you have.
• Torque and retorque: torque spec guidance comes from Audi and the wheel maker. I torque in a star pattern, then recheck after a short shakedown drive. Your exact torque value should be confirmed in the owner’s manual or service literature.

If any dimension above is unknown on your car, the rule of thumb is to pause and verify. Your door placard, the factory wheel’s part number inside a spoke, and the owner’s manual are reliable OEM sources. The calculator helps visualize, but the car tells the truth.

5. Validate

Before paying for a full set, I validate in three quick steps.

• Calculator pass: confirm inner clearance is positive, outer poke looks reasonable, and overall tire diameter sits close to your baseline.
• Physical pass: test fit one front and one rear if possible. Spin the wheel by hand to check caliper and liner clearance. Turn to full lock left and right.
• Road pass: short drive over gentle bumps and a low-speed full-lock turn in a parking lot. Listen for rubbing, then recheck torque.

If something feels off, return to the calculator and adjust by a small increment. A 3 to 5 mm offset change or a 5-profile aspect change can make the difference between rubbing and clean clearance.

Helpful tools

• Torque wrench for accurate tightening
• M14 x 1.5 wheel bolts matched to your wheel seat
• 66.6 hub-centric rings for aftermarket wheels with larger bores
• TPMS programming tool if your car uses in-wheel sensors

6. Summary

Here is the quick recap for the 2009 Audi S5 page you are on. The provided OEM data lists 5x112 bolt pattern, 66.6 mm center bore, M14 x 1.5 threads, and an example wheel at 20x9 ET29 with 5.64 in backspacing, while the tire row shows 245/40R18. Treat that as a clue that multiple factory configurations exist. Confirm your baseline from the door placard or your current tire and wheel markings, then mirror it in the calculator.

Use the calculator to trial small changes in width, offset, and tire size. Think in terms of inner clearance and outer poke, keep overall diameter close to stock as a rule of thumb, and align hardware to Audi’s hub and thread specs. Validate with a test fit before buying. That step-by-step approach has kept my S5 projects clean, safe, and rattle free, and it gives you the confidence to pick a wheel and tire package that feels right the first time.