WHEEL OFFSET CALCULATOR

Before you compare: Overall rim width is estimated as advertised wheel width plus 1.00 inch. Actual flange dimensions vary, so verify the wheel manufacturer’s specifications and physically check suspension, brake, steering, and fender clearance.

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Wheel comparison specifications

Wheel 1

Default example: 17 × 7.5-inch wheel. The 17-inch diameter does not affect lateral wheel position.

Nominal wheel width

The wheel’s advertised metal-rim width between bead seats—for example, 8.5 in in a 17 × 8.5 wheel. This is not tire width.

Measurement provided

Offset Backspacing

Choose the specification supplied by the wheel manufacturer.

Offset

Offset is the mounting pad’s distance from the wheel centerline. Positive offset pulls the wheel inward; negative offset pushes it toward the fender.

Wheel 2

Default example: 17 × 8.5-inch wheel. The 17-inch diameter does not affect lateral wheel position.

Nominal wheel width

The wheel’s advertised metal-rim width between bead seats—for example, 8.5 in in a 17 × 8.5 wheel. This is not tire width.

Measurement provided

Offset Backspacing

Choose the specification supplied by the wheel manufacturer.

Backspacing

Backspacing is the distance from the mounting pad to the inner wheel lip. More backspacing generally moves the wheel inward.

Results update automatically.

Shared-scale wheel cross-section Horizontal dimensions are to scale; vertical wheel thickness is diagrammatic.

WHAT IS WHEEL OFFSET?

Wheel offset is the distance in milimeters measured between the surface where the wheel mounts to the hub and the centerline of the wheel. Wheel offset is described in the following ways:

Positive Offset

This is where the mounting surface of the wheel is very close to the outer edge of the wheel, tucking the wheel further into the wheel well.

Zero Offset

This is a neutral wheel, where the mounting surface is lined up with the ceterline of the wheel.

Negative Offset

A wheel with a negative offset has the mounting surface further away from the outside lip of the wheel, which in-turn means the wheel will poke out further from the wheel well.

BACKSPACING vs OFFSET

Where wheel offset measures the distance from the hub mounting surface of the wheel to it’s centerline in millimeters. backspacing measures the distance from the hub mounting surface to the edge of the back lip of the wheel in inches. So offset can be positive or negative, but backspacing can only be a positive number.

WHY DOES OFFSET MATTER?

The factory wheel and tire package on your vehicle is designed to work with the suspension, steering and brakes. When you want to add new wheels and tires there are some things that you need to consider.

If the wheel you are adding has a more positive offset than your stock wheels it might have problems clearing the brakes, suspension or parts of the body or frame.

A wheel with negative offset might be used to make room for larger brakes or shocks, or to move the wheel and tire further away from the body to provide more clearance when the tire is taller and or the wheel is at full-stuff in the wheel well.

WHAT ABOUT SCRUB RADIUS?

Scrub radius is the distance between where the centerline of the tire and an imaginary line drawn through the pivot points of your ball joints or kingpin (called the steering axis inclination), meet the ground.

The manufacturer designs the wheel and tire package to have the smallest scrub radius possible. On a truck or a jeep it will typically be less than an inch, which should give good steering feel.

If you were to change your wheels to a negative offset, while keeping the same sized tire, then you are going to increase the scrub radius. This will put extra load on your steering components and it may cause the tire to toe out during heavy braking. It may also make the steering feel more darty and your vehicle may tramline (or get stuck in road grooves) more easily.

If you add a taller tire the distance between the hub and the ground increases, which in turn reduces the scrub radius. However, it may still be greater than stock.

Below is an example for a Jeep JL. The picture on the left shows the wheel and tire from the Xtreme 35 package. You can see the scrub radius from the factory is a little over two inches. By comparison the picture on the right shows a 9 inch wide wheel with 3.5 in backspacing, which might be typcial for a lifted Jeep. It has a 37 inch tire, so it’s taller, but that doesn’t make up for the difference in backspacing, so the scrub radius is now a little over 4 inches. You might feel this larger scrub radius as different steering characteristics and you will probably want to upgrade to beefier ball joints!