Audi TT MK1 Wheel Bolt Sizes Explained

The factory wheel bolts on the Audi TT Mk1 (8N, built 1998–2006) are M14 x 1.5 with a 27 mm thread length, a 60° cone (tapered) seat, and typically a 17 mm hex head. This specification applies to the standard OEM alloy wheels, though thread length and head type can vary if wheels or hardware have been changed.

Contents

Why Wheel Bolt Size Matters on the Audi TT MK1
Core Specifications of OEM Audi TT MK1 Wheel Bolts
Variations Between Models and Setups
Safety, Torque Specs, and Best Practices
Summary

Why Wheel Bolt Size Matters on the Audi TT MK1

The first-generation Audi TT shares much of its platform with contemporary Volkswagen models, but wheel hardware is not fully interchangeable across all VAG cars. Using the wrong bolt size or seat type can damage wheels, cause vibration, or, in the worst case, lead to a wheel working loose. Understanding the exact bolt specs is essential when changing wheels, fitting spacers, or replacing lost hardware.

Core Specifications of OEM Audi TT MK1 Wheel Bolts

The wheel bolts on the TT Mk1 follow a fairly standard VAG pattern for performance-oriented models of that era, but there are a few critical measurements owners should know.

Main Dimensions and Thread

The most important dimensions relate to the bolt diameter, thread pitch, and thread length. These define what will physically screw into the hub and how much engagement you get in the hub’s threaded holes.

Thread diameter: M14 (14 mm)

Thread pitch: 1.5 mm (M14 x 1.5)

Standard thread length (OEM alloys): approx. 27 mm

Overall bolt length: around 50–55 mm, depending on head design, but the critical part is the threaded section (about 27 mm)

Hex size: 17 mm (some aftermarket bolts may use 19 mm)

Together, these measurements define bolts that match the TT Mk1 hub and provide sufficient thread engagement without bottoming out in the hub or leaving too few threads in contact for safety.

Seat Type: Cone vs. Ball

The way the bolt contacts the wheel—its “seat”—is just as important as the thread size. Using the wrong seat type can crack, deform, or loosen wheels.

OEM Audi TT Mk1 alloy wheels: 60° conical (tapered) seat bolts

Common VAG steel wheels: often use radius (ball) seat bolts

Aftermarket wheels: typically use 60° conical seat, but always verify with the wheel manufacturer

Never mix seat types: cone bolts in ball-seat wheels (or vice versa) are unsafe

The conical seat used on the TT Mk1 acts as a centering surface and clamping interface; if mismatched, the wheel may not sit flat on the hub, leading to wobble, uneven torque, and potential loosening.

Variations Between Models and Setups

While the core specification is consistent, different TT Mk1 variants and modifications—such as wheel size upgrades or spacers—can affect the appropriate bolt length and type.

Standard TT, Quattro, and 225 Models

Across most factory configurations—front-wheel-drive and quattro, 180 hp and 225 hp models—the basic bolt spec remains the same. Differences more often arise from the wheels themselves than from the drivetrain.

TT Mk1 8N (1998–2006): M14 x 1.5 thread, conical seat

Common factory wheel sizes: 16″, 17″, and 18″ alloys, all using similar bolt specs

Hub design: 5 x 100 PCD, center bore 57.1 mm (affects wheels and spacers, not bolt thread)

OEM bolts: standard steel, zinc-coated or similar corrosion protection

Even if your TT has different wheel diameters or styles from the factory, the bolts are still M14 x 1.5 with a conical seat; only specific length or cosmetic features might differ slightly.

Using Wheel Spacers and Aftermarket Wheels

Many TT Mk1 owners fit spacers or aftermarket alloys to improve stance or clear big brakes, and this is where bolt length and type need closer scrutiny.

Spacers (bolt-on or slip-on): generally require longer bolts to maintain thread engagement

Typical extra length needed: increase bolt thread length by approximately the thickness of the spacer (e.g., +10 mm thread length for a 10 mm spacer)

Seat type with spacers: must still match the wheel’s seat (usually 60° conical for TT alloys)

Aftermarket wheels: confirm:
- seat type (cone vs. ball)
- required bolt length (some wheels have thicker mounting pads)
- whether special “tuner” bolts or locking bolts are needed

Upgrades like spacers and non-OEM wheels can be safe and effective, but only if you ensure that the new setup preserves correct seat type and sufficient thread engagement with appropriately sized bolts.

Safety, Torque Specs, and Best Practices

Correct bolt size is only part of the picture; proper installation and torque are vital to keep the wheels safely attached and to protect suspension and brake components.

Recommended Torque and Installation Tips

Applying the right torque and following basic installation guidelines helps avoid warped brake discs, stripped threads, and loose wheels.

Typical torque for Audi TT Mk1 wheel bolts: approx. 120 Nm (about 88–90 lb-ft); always confirm against your specific owner’s manual or service data

Tightening pattern: use a star (criss-cross) pattern to seat the wheel evenly

Check torque: re-check after 50–100 km (30–60 miles), especially with new wheels or spacers

Thread condition: bolts and hub threads must be clean, undamaged, and free from heavy corrosion

Lubrication: generally, VAG specifies dry threads—do not oil or grease unless the manufacturer explicitly instructs; lubrication changes torque behavior

Following these practices ensures that even correctly sized bolts perform as intended, keeping the wheel firmly clamped and evenly seated on the hub.

How to Confirm You Have the Right Bolts

Given the age of most TT Mk1s, many now run non-original wheels or hardware. A quick check can prevent unsafe combinations.

Measure thread diameter: should be 14 mm for correct fitment (M14)

Check pitch: count threads over a 15 mm span—there should be 10 threads (1.5 mm pitch)

Verify seat: visually compare to the wheel’s bolt holes:
- cone seat: straight, angled sides
- ball seat: rounded profile

Confirm thread engagement: with wheel installed, you should get roughly 7–8 full turns on the bolt before it seats, indicating adequate engagement length

Consult documentation: check the wheel manufacturer’s data or Audi service documentation where available

These basic checks are straightforward and can be done at home, offering reassurance that your TT’s wheel hardware is correctly matched to the hubs and wheels.

Summary

The Audi TT Mk1 (8N) uses M14 x 1.5 wheel bolts with a 27 mm threaded section, 60° conical seats, and typically 17 mm hex heads for its OEM alloy wheels. This standard applies across most factory TT Mk1 variations, although modified setups with spacers or aftermarket wheels may require different bolt lengths. Ensuring the correct thread size, seat type, and torque—around 120 Nm—remains crucial to safe, reliable wheel fitment on this first-generation TT.

What size are the lug nuts on a 2001 Audi TT?

14 mm x 1.5 thread size, 17 mm hex, 1.1″ shank length.

What size lug nuts does Audi use?

Most modern Audis use M14x1.5 lug bolts with a 17mm hex head and a ball seat. It is crucial to verify your specific model, as some exceptions exist, such as some e-tron models using a 19mm hex, and older models may differ. The seat type is also important, so always double-check if you need a ball or conical seat for your wheels.
Key specifications

Thread Pitch: M14x1.5
Hex Size: 17mm (common)
Seat Type: Ball Seat (common)
Shank Length: Varies by model; some common lengths are 27mm or 28mm

Important considerations

Always check your owner’s manual: This is the most reliable way to confirm the exact size and specifications for your vehicle.
Confirm seat style: Ensure the seat type (ball or conical) matches your wheels. Using the wrong one can cause damage.
Note on hex size: While 17mm is most common, some specific models, like the e-tron GTS, use a 19mm hex.
Use the right tool: Use the correct socket size and a torque wrench for proper installation. Some models have a plastic cap over the lug, which requires a special tool to remove.

What size are Audi wheel bolts?

Most modern Audi models use M14x1.5 wheel bolts with a 17mm hex head and a ball or radius seat. The exact shank length can vary, but common lengths are 27mm or 28mm. For some older or 4-lug models, a smaller M12x1.5 size may be used instead.
Common specifications for most Audi models

Thread size: M14x1.5
Hex size: 17mm (except for some e-tron models, which use a 19mm hex)
Seat type: Ball (radius) seat is standard for factory wheels. Aftermarket wheels might require a cone (conical) seat
Shank length: Commonly 27mm or 28mm, but this can vary by model year

Other sizes

M12x1.5: Used for some older 4-lug Audi and Volkswagen models