How to measure wheel backspacing: the short answer
Wheel backspacing is the distance from the hub mounting face to the inner rim edge. To measure it: lay the wheel face-down (outer face on the bench), place a straight edge across the inner flanges, and measure vertically from the straight edge down to the mounting pad. That reading is backspacing.
Backspacing is common in US truck and off-road fitment talk. Passenger-car and custom forged wheel makers more often quote offset (ET). You can convert either way when you know the width — see wheel offset vs backspacing.
| Step | What to do |
|---|---|
| 1 | Remove the tire if you can; measuring on the rim flange is cleaner |
| 2 | Lay the wheel outer-face down on a flat surface |
| 3 | Rest a rigid straight edge across both inner rim flanges |
| 4 | Measure from the underside of the straight edge to the hub mounting pad |
| 5 | Record units (inches or mm) and the wheel’s stamped width |
Step-by-step measuring wheel backspacing
Use a rigid straight edge (a level or steel rule) that spans the full inner diameter of the rim. Soft tape alone can sag and skew the reading. Measure in the middle of the mounting pad, not on a raised logo or valve area.
If the tire is still mounted, rest the straight edge on the rim flange, not on the tire sidewall. Sidewall height is not part of backspacing. For offset measurement from the same setup, see how to measure wheel offset.
Convert backspacing to offset
Work in one unit. Convert width to millimetres (inches × 25.4) if needed.
- Offset = backspacing − (width ÷ 2)
- Backspacing = (width ÷ 2) + offset
Example (math only): a 9 in (228.6 mm) wide wheel with 5.88 in (149.3 mm) nominal backspacing has offset ≈ 149.3 − 114.3 = +35 mm. Plug current and new numbers into the wheel offset calculator to see how inner and outer clearance change.
Common mistakes
- Measuring to the tire instead of the rim flange
- Using a floppy tape that bows across the opening
- Mixing nominal bead-seat width with flange-to-flange width without saying which
- Forgetting that a spacer reduces effective backspacing by its thickness
- Assuming the same backspacing on a wider wheel keeps the same outer position — it does not; width changes both sides
Backspacing vs frontspacing
Frontspacing is the distance from the mounting face to the outer rim edge: (width ÷ 2) − offset. Together with tire sidewall shape, it sets how close you sit to the fender. Backspacing sets the inside. Quoting only one number without width leaves the other side unknown.
If a forum post lists “4.5 in backspacing” with no width, you still cannot reverse to a unique offset. Always record width alongside backspacing.
Why backspacing matters on custom wheels
Inner clearance to struts, springs and control arms is set by backspacing. When you order a custom forged set you can specify the backspacing (or the offset and width that produce it) so the barrel clears suspension while the outer face hits your flush target. Pair that with brake clearance from the BBK guide and the full fitment checklist.
Measuring wheel backspacing FAQ
What is wheel backspacing?
The distance from the hub mounting face to the inner rim edge.
How do I measure wheel backspacing at home?
Wheel face down, straight edge across the inner flanges, measure down to the mounting pad.
Is backspacing the same as offset?
No. They locate the same mounting face from different references. Convert with width.
Should I use inches or millimetres?
Either, as long as you stay consistent and convert width and offset to the same unit before calculating.
Does more backspacing tuck the wheel in?
More backspacing moves the inner edge closer to suspension and, at the same width, usually means higher (more positive) offset and a more tucked outer face.
Can VEXORA build to a measured backspacing?
Yes. Send the measurement with width, PCD and brake details. Every VEXORA set is made to order, and custom orders start from a single pair. MOQ: 1 pair (2 wheels). Production typically takes approximately 20 days once the specification, drawings and finish are approved, confirmed per project. Shipping time varies by destination country. Where DDP (Delivered Duty Paid) is available for your country, orders ship DDP: import duties and taxes are handled and the wheels are delivered to your door.
Send your backspacing with the brief
Request a quote for custom forged wheels. Email sales@vexoraforged.com or message WhatsApp +86 159 2056 8771.