Wheel Offset and ET Tool
Wheel Offset Calculator: Convert ET to Backspacing for Custom Wheels
Use this wheel offset calculator to estimate backspacing from wheel width and ET. It helps custom wheel buyers compare fitment, wheel position and quotation specifications before production.
Calculate Backspacing From Offset
Enter wheel width and offset to estimate backspacing. Offset is the distance from the wheel centerline to the mounting face. Positive ET moves the wheel inward; negative ET moves it outward.
This estimate includes a common 1 inch total rim lip allowance. Final fitment depends on wheel profile, tire size, brake clearance and suspension setup.
Offset Formula
Approximate backspacing:
Backspacing = (wheel width + 1 inch) / 2 + ET / 25.4
Positive offset:
The mounting face is closer to the outside of the wheel, usually moving the wheel inward.
Negative offset:
The mounting face is closer to the inside of the wheel, usually pushing the wheel outward.
Offset Reference
Common Offset and Fitment Effects
Offset affects wheel position, fender clearance, suspension clearance and brake clearance. It should be reviewed together with wheel width and tire size.
| Offset range | Typical effect | What buyers should confirm |
|---|---|---|
| Positive ET | Wheel usually sits more inward toward the suspension side | Inner clearance, strut clearance and brake clearance |
| ET0 | Mounting face is close to the wheel centerline | Vehicle application, wheel width and tire setup |
| Negative ET | Wheel usually sits more outward toward the fender side | Fender clearance, scrub radius and legal fitment limits |
| Higher ET with wider wheel | May still move close to suspension components | Compare inner and outer position change carefully |
| Lower ET with wider wheel | May create a more aggressive stance | Check fender clearance and tire rubbing risk |
Buyer Checklist
Offset Should Be Quoted With Full Wheel Specs
For a custom wheel quote, ET alone is not enough. Send the complete wheel specification package so the supplier can review fitment and manufacturability.
FAQ
Wheel Offset Calculator Questions
Short answers for buyers comparing offset, ET and backspacing before placing a custom wheel order.
What does ET mean on wheels?
ET is the wheel offset in millimeters. It measures the distance between the wheel centerline and the hub mounting face.
Is offset the same as backspacing?
No. Offset is measured in millimeters from the wheel centerline. Backspacing is measured from the mounting face to the inner wheel edge.
Does lower offset make wheels stick out more?
Usually yes. A lower or negative offset generally moves the wheel outward, but the final position also depends on wheel width.
Can I order custom wheels with my required ET?
Yes. Custom wheel projects can usually be reviewed with requested offset, PCD, center bore, finish and quantity, subject to manufacturing feasibility.
Custom Wheel RFQ
Need Custom Wheels With Exact Offset?
Send your required wheel size, ET, PCD, center bore, finish and quantity to CustomWheelHub. Clear specifications help speed up quotation and factory review.
Copyable RFQ Template
Ready to Source Forged Wheels?
- Custom Forged Wheel Manufacturer — one-off and OEM custom projects
- Private Label Forged Wheels — your brand, caps and packaging
- Forged Wheel Dealer & Wholesale Program — for distributors, shops and online retailers
Send your vehicle, size, PCD, ET, center bore, finish, quantity and destination through our quote request form.
Get a quick forged wheel quote
Send your vehicle platform, wheel size, PCD, offset, finish and quantity. We confirm fitment and reply within 24 hours.
Pingback: How to Read a Forged Wheel Drawing & Spec Sheet
Pingback: Audi RS Forged Wheel Fitment & Brake Guide
Pingback: Toyota Off-Road Forged Wheel Fitment Guide
Pingback: Mercedes-AMG Forged Wheel Fitment Guide
Pingback: Wheel Bolt Pattern Cross-Reference Chart
Pingback: Forged Wheel Concavity & Spoke Design