Wheel Offset Calculator
Eyeing new wheels? Compare your current setup to the new one and see exactly how much closer to the fender (poke) and the suspension the new wheels will sit — spacers included.
Current wheel
8" · ET45- Outer lip from hub face
- 57 mm
- Inner lip from hub face
- 147 mm
- Backspacing
- 6.27"
New wheel
9" · ET35- Outer lip from hub face
- 79 mm
- Inner lip from hub face
- 149 mm
- Backspacing
- 6.38"
8" · ET45 → 9" · ET35
Changing tire size too? Pair this with the tire size calculator to check overall diameter and speedometer error.
What is wheel offset?
Offset (marked ET on the wheel) is the distance in millimeters from the wheel's mounting face to its centerline. Positive offset tucks the wheel inward toward the suspension; lower or negative offset pushes it out toward the fender. Two wheels with the same width but different offsets sit in completely different places.
That's why you can't judge fitment by offset alone — width matters just as much. Going from an 8″-wide ET45 wheel to a 9″-wide ET35 moves the outer lip out by about 23 mm: 12.7 mm from the extra inch of width and 10 mm from the offset change. A bolt-on spacer works the same way as reducing offset by its thickness.
Found a setup that fits? Log the wheel specs — and every other mod — in your Ryvve garage so your build sheet is always in your pocket at the next meet.
Frequently Asked Questions
Enter the width (in inches) and offset (ET, in millimeters) of your current and new wheels, plus any spacer. The calculator works out where each wheel's outer and inner lips sit relative to the hub face, then shows how much farther out toward the fender (poke) and how much closer to the suspension the new setup sits compared to what's on the car now.
Log the New Setup in Your Garage
Wheels are never the last mod. Ryvve's garage keeps every spec, photo, and stage of your build in one place — free on iOS and Android.
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