How to Choose the Right Wheel Spacers for a Perfect Fender Fit

Mario's Wheel Repairs
12 February 2025
How to Choose the Right Wheel Spacers for a Perfect Fender Fit

When upgrading your car's stance, handling, or wheel clearance, wheel spacers are a popular solution. Whether you're looking for 4×100, 5×114.3, or any other bolt pattern, choosing the right thickness and type of spacer is crucial. Let’s break down what you need to consider.

Prioritising Safety

  • Avoid Cheap or Unbranded Spacers: Poorly machined or low-quality materials can cause failures, leading to dangerous driving conditions.
  • Thickness Matters: Excessively thick spacers (30mm+) alter suspension geometry and increase stress on wheel bearings, potentially leading to premature wear or failure.
  • Professional Installation Recommended: Even with DIY experience, getting a professional alignment and torque check ensures safety. Consult a qualified professional to ensure proper installation and compatibility.
  • Torque Specifications Are Critical: Proper torque application prevents uneven stress on the wheel assembly, which can cause wheel wobble, vibrations, or even stud failure. Always consult your vehicle’s service manual or a professional to determine the correct torque values.

Spacer Types: Slip-On vs. Bolt-On

Slip-On Spacers

  • Fit between the wheel and hub
  • Available in various bolt patterns (e.g., 4×100, 5×120, 6×139.7)
  • Best for thinner applications (3mm-10mm)
  • Require longer wheel studs for proper engagement
  • Safety Tip: Ensure at least the length of the stud’s diameter in full thread engagement for security.

Bolt-On Spacers

  • Secure directly to the hub and provide new studs
  • Used for thicker applications (15mm+)
  • More secure than slip-on spacers
  • Available in various sizes and patterns
  • Safety Tip: Verify that existing studs do not protrude beyond the spacer face, which could prevent proper wheel seating.

Hub-Centric vs. Lug-Centric Spacers

  • Hub-Centric Spacers: Designed to match the hub’s centre bore, ensuring a perfect fit and even load distribution. This is the safest option and eliminates vibrations.
  • Lug-Centric Spacers: Centred only by the wheel nuts, which can cause misalignment and vibrations at higher speeds. Not recommended for long-term use.

Always choose hub-centric spacers to maintain vehicle stability and safety.

Material Quality Matters

Not all spacers are created equal. High-quality spacers are typically made from billet aluminium, which offers superior strength while remaining lightweight. Cheaper cast materials may be prone to cracking or failure under load. Always opt for reputable brands that use CNC-machined aluminium for precise fitment and durability.

How to Determine the Right Spacer Thickness

The correct thickness depends on how far your wheels sit inside the wing. Here’s how to measure:

  • Use a Straight Edge: Place a straight edge vertically against the wing.
  • Measure the Gap: Use a ruler or calliper to measure the distance from the wheel's outer edge to the wing.
  • Select the Spacer Size: Choose a spacer thickness close to the measured gap while allowing clearance for suspension movement.

Common Spacer Sizes & Their Effects

  • 3mm-5mm: Minimal change, mainly for fine-tuning stance.
  • 10mm-15mm: Brings wheels closer to flush with mild improvement in handling.
  • 20mm-25mm: Aggressive fitment, often used for stance builds.
  • 30mm+: Extreme setups, may require additional modifications.

Additional Modifications for Larger Spacers

  • Wing Rolling or Trimming: To prevent rubbing when turning or going over bumps.
  • Extended Wheel Studs: If using slip-on spacers over 5mm.
  • Suspension Adjustments: To correct camber angles altered by wider track width.
  • Brake System Considerations: Verify that spacers do not interfere with callipers or brake components.

Wheel Nut Compatibility

When using spacers, it’s crucial to use the correct type of wheel nuts for both the spacers and the wheels being installed. The wrong wheel nuts can lead to improper seating, vibrations, or even wheel detachment. Always verify that:

  • The wheel nuts match the thread pitch of your vehicle.
  • The wheel nuts provide proper seating (tapered, ball, or flat).
  • You consult a professional if unsure about compatibility.

Insurance & Legal Considerations

  • Any modification to your wheels and suspension may impact your insurance cover.
  • Some insurers consider wheel spacers a non-approved modification, voiding cover in an accident.
  • Certain jurisdictions have legal restrictions on spacer use, requiring approval or additional certification.

Check with your insurer and local laws before installing spacers to avoid potential cover issues or fines.

Final Thoughts

If you want a flush look with the wing, measuring the gap is the best approach to choosing the right wheel spacers. For most vehicles, 10mm-20mm spacers offer a clean fit without major modifications.

Key Takeaways:

  • Always prioritise safety over aesthetics.
  • Use hub-centric spacers for stability.
  • Follow proper torque specifications.
  • Choose high-quality materials like billet aluminium.
  • Consult your insurer before making changes.
  • Always use the correct wheel nuts for spacers and wheels.