Vibe Tools · Free fitment calculator
Wheel Offset Calculator
See exactly how a new wheel will sit before you buy. Enter the width and offset of your current and new wheel, and we'll show how far it moves out toward the fender and in toward the suspension.
Current wheel
New wheel
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Offset and width decide where a wheel sits; diameter doesn't change it. Based on the standard 1/2" bead flange on each side. Going smaller in diameter? Make sure it clears your brakes. Not sure? Ask our fitment team.
What is wheel offset?
Offset, stamped on the wheel as ET, is the distance in millimeters from the wheel's centerline to the face that bolts to your hub. It decides where the wheel sits in the fender.
Positive offset (most modern cars) pulls the wheel in under the fender. Zero offset puts the mounting face on the centerline. Negative offset pushes the wheel out, common on lifted trucks.
Offset vs backspacing
Backspacing is the distance from the mounting face to the inner lip, usually in inches. Truck fitment charts use it because it shows how much room you have before the wheel hits the suspension. Front spacing is the same measurement to the outer lip. The calculator shows all three.
How much change is too much?
Up to 5 mm of extra poke or inner movement almost always fits.
5 to 15 mm of extra poke fills the fender. Tire size, ride height and camber decide whether it rubs.
Over 15 mm of extra poke usually needs a fender roll, more negative camber or a different offset. Over 10 mm closer to the suspension can hit struts or calipers.
Pair your wheel with the right tire using our tire size calculator, or see proven sizes in our Velgen Mustang and E5 Corvette fitment guides.
Wheel offset FAQ
What does ET mean on a wheel?
ET comes from the German "Einpresstiefe" and means offset in millimeters. ET35 is +35 mm offset.
Does a lower offset make the wheel stick out more?
Yes. At the same width, every millimeter of lower offset moves the wheel 1 mm further out.
Can I use spacers instead?
A spacer lowers your effective offset by its thickness: a 10 mm spacer on an ET45 wheel behaves like ET35.
Does this work for trucks?
Yes. Switch to inches to see backspacing the way truck fitment charts list it.