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How to Measure Forged Wheels for Perfect Fitment?

One of the most important steps before ordering forged wheels is making sure the fitment is 100% correct.
And that starts with knowing how to measure your wheels properly.

Whether you’re replacing stock wheels or designing something fully custom, I always recommend confirming five key measurements. Let me walk you through them — simple, accurate, and supplier-ready.


Why Wheel Fitment Matters

Incorrect wheel fitment can lead to:

  • Rubbing on fenders or suspension
  • Brake caliper interference
  • Unsafe driving behavior at high speed
  • Failed installation or return delays

Custom forged wheels are machined to order, so mistakes in size or spec can’t be adjusted afterward. That’s why we always double-check every fitment detail before production.


Key Measurements for Forged Wheel Fitment

✅ 1. Diameter (Inches)

  • Measured from edge to edge across the wheel (excluding the tire)
  • Typical range: 17″ to 24″
  • Affects tire selection and brake clearance

✅ 2. Width (J)

  • Distance from inner to outer bead (where the tire seats)
  • Usually written like 9.5J, 10J, 12J, etc.
  • Wider wheels offer better traction but may require body modification

✅ 3. Offset (ET)

  • The distance between the wheel hub mounting surface and the centerline of the wheel
  • Written as ET+35, ET0, or ET-25, etc.
  • Controls how far the wheel sticks in or out of the fender
  • Critical for aggressive stance or brake clearance

✅ 4. PCD (Bolt Pattern)

  • Stands for Pitch Circle Diameter
  • Includes the number of bolt holes and the circle diameter
  • Examples: 5×114.3, 5×112, 6×139.7
  • Must match your vehicle exactly

✅ 5. Center Bore

  • The hole in the middle of the wheel that sits over the car’s hub
  • Needs to be hub-centric for perfect balance
  • Sizes vary (e.g., 66.6mm, 73.1mm)

Optional but Useful: Backspacing & Brake Clearance

For widebody or racing builds, I may also ask for:

  • Backspacing (distance from hub to wheel back edge)
  • Brake caliper dimensions or template (PDF or photo)
  • Suspension type (stock, air suspension, or coilovers)

These help avoid common clearance issues during aggressive fitment setups.


How to Send the Info

When you work with me at FLEXIFORGED, here’s what helps the most:

  • A clear photo of your current wheels mounted on the vehicle
  • Any label or engraving showing specs (inside the wheel barrel)
  • If available, your tire size (e.g., 275/35R20)

If you have no data — no problem. Just tell me your car brand, model, and year. I’ll look up the OEM fitment and recommend a safe, stylish spec for your goals.


Final Tips

  • Use a measuring tape for quick checks
  • Use a vernier caliper for center bore if needed
  • Always measure wheels without the tires mounted for best accuracy

The better the data, the better your wheels will fit — and the happier your end customer will be.

Jackie Wei

Hi, I'm the author of this post, and I have been in this field for more than 10 years. If you want to customize forged wheels or forged wheels related product, feel free to ask me any questions.

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