2008 Audi A5 Wheel Interchange

Starting point: the 2008 Audi A5 stock fitment I work from

When I set up a wheel change on a 2008 Audi A5, I start with a simple mental model. Think of it as five anchors that define how a wheel sits: bolt pattern and thread type, center bore and hub seating, width and diameter, offset and backspacing, and the tire’s overall size. With those in view, the rest becomes a structured comparison instead of guesswork.

Some details can vary by package or regional trim, especially brake clearances. If your A5 build differs, use the on-page calculator to verify clearances and cross-check with your owner’s manual or an OEM parts catalog by VIN.

Small win: sanity-check a simple swap in the calculator

The quickest confidence boost comes from running a like-for-like comparison. I do this before touching a jack. In the calculator, set “Installed on (your vehicle)” to the 2008 Audi A5. Then pick “Wheels from (donor vehicle)” that match the numbers above, or type in the exact OEM dimensions under “Custom wheel size.” You’ll see how the calculator tracks inner and outer clearance changes, and it pairs tire diameter to rim diameter for an apples-to-apples view.

Think of this first pass as a baseline. If the donor set matches the table, the change readouts should be close to zero. That tells you the tool is set up correctly and your starting data is sound.

Expand scope: explore sizes with a clear mental model

Once the baseline looks right, I experiment in small steps. I adjust only one variable at a time to see the effect. Here’s how I approach it:

• Width and offset: increasing width pushes both inner and outer lips out; offset then shifts the wheel inboard or outboard. The calculator shows both inner clearance and poke. Rule of thumb: keep changes modest and watch the inner clearance number around struts and liners.
• Diameter and tires: change rim diameter under “Custom wheel size,” then select a “Custom tire size” that keeps overall tire diameter close to stock. The calculator updates tire diameter in the comparison so you can watch fender gap and speedometer impact.
• Backspacing view: use backspacing to understand how much of the wheel sits inboard. It’s a helpful second lens alongside ET.

If you’re considering 18 or 19 inch options, I try a likely tire match in the tool, check inner clearance, then review outer poke relative to the fender. The visual plus the numbers gives a practical picture before you spend money.

Refine: hardware details, hub centricity, and brake clearance

This is where small details make a big difference in how the car drives and how the wheels wear.

• Center bore and rings: the A5 hub is 66.6 mm. If an aftermarket wheel has a larger center bore, plan for quality hub-centric rings sized to 66.6 mm so the wheel seats properly on the hub. They support vibration-free mounting. Search example: 66.6 hub centric rings.
• Bolts and seating: thread size is M14 x 1.5. Seat type (ball vs cone) depends on the wheel; match the bolt seat to the wheel seat. If you change spacers or wheel designs, confirm proper bolt length and seating with the wheel or spacer supplier. Search example: Audi wheel bolts M14x1.5.
• Offset strategy: lower ET moves the wheel outward; higher ET tucks it inward. I nudge offset in small increments in the calculator, watching inner clearance first, then outer poke.
• Brake and spoke shape: two wheels with the same size can clear brakes differently. The spoke curve and barrel profile matter. If you’re close on inner clearance, request a brake template from the wheel vendor or do a careful test fit before mounting tires.
• Load rating: pick wheels and tires with ratings that meet or exceed the vehicle’s requirements. Your door placard and owner’s manual help confirm this.

Validate: my pre-install checklist for the A5

Before committing, I run through a short safety-first routine. It keeps surprises out of the shop bay and off the road.

• Use the calculator to confirm inner clearance and overall tire diameter changes are reasonable for your roads and suspension.
• Confirm hub bore fitment and have rings ready if needed.
• Match bolt seat type to the wheel and verify thread engagement per OEM guidance. Avoid mixing hardware from different wheel systems.
• Test fit one corner without a tire when possible. Spin the wheel by hand, check caliper, knuckle, and strut clearance, then turn lock to lock.
• Mount tires and balance. After installation, torque bolts to the factory spec from your owner’s manual using a calibrated wrench. Example tool: 1/2 inch torque wrench.
• Road test, watch for vibration, rubbing, or steering pull. Re-torque after a short shake-down period.
• If any spec differs on your trim, verify with your VIN at an Audi parts counter or an OEM catalog. The calculator helps visualize, the OEM source confirms the numbers.

Summary: quick recap

Start with the known 2008 Audi A5 specs: 5x112, 66.6 mm center bore, M14 x 1.5 bolts, 17x7.5 ET28 with 225/50R17 tires and 4.85 in backspacing. Use the calculator as your mental model in motion, tweaking one variable at a time to see inner clearance, poke, and tire diameter changes. Refine your plan with hub-centric rings where needed, the correct bolt seat, and a careful eye on brake clearance. Validate with a test fit and proper torque. The process moves from exploratory to resolved quickly, and you’ll end up with a setup that fits cleanly and drives the way an A5 should.