Wheel Offset Calculator
Enter the current and new tire width and offset to calculate the offset and change to the inner clearance and outer position.
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How to Calculate Wheel Offset Changes
Wheel offset is defined as the distance, measured in millimeters, from the wheel’s hub mounting surface to its centerline. A given wheel can have either a negative offset, a zero offset, or a positive offset. Here’s what these terms mean:
Negative offset: The wheel’s hub mounting surface is located rearward of the centerline of the wheel, closer to the rear of the wheel. This has the effect of moving the wheel farther outward, away from the vehicle’s suspension.
Zero offset: The wheel’s hub mounting surface is on the centerline of the wheel.
Positive offset: The wheel’s hub mounting surface is located forward of the centerline of the wheel, closer to the “face” of the wheel. This has the effect of moving the wheel farther inward, closer to the vehicle’s suspension.
Wheel offset is important because it allows for the correct positioning of your new wheels within the wheel wells of your vehicle, letting the new wheels clear both the suspension components on the inside and the fenders on the outside.
To recap, a negative offset will move the wheel farther out, and a positive offset will move the wheel farther in.
How to Calculate the Inner Clearance Change
When changing wheel offsets, you can use the following formulas to calculate how much the inner clearance will change with the new wheels.
Start by finding the distance between the inner edge of the wheel and the hub mount for both the current wheels and the new wheels using this formula:
inner distance from hub mount = (width ÷ 2) + offset
Then, calculate the change in the inner wheel clearance by subtracting the inner distance from the hub mount for the new wheel from that of the current wheel:
inner wheel clearance change = current wheel inner distance from hub mount – new wheel inner distance from hub mount
The wheel width will often be measured in inches, while the wheel offset is measured in millimeters. All of the dimensions in the formulas must be in millimeters. You can use our inches to millimeter converter to quickly convert the wheel width to millimeters.
How to Calculate the Outer Wheel Position Change
The position of the outer side of the wheel may also change if the width or offset of the new wheel changes. Use the following formulas to find the change to the position of the outer side of the wheel.
Start by finding the distance between the outer edge of the wheel and the hub mount for both the current wheels and the new wheels using this formula:
outer distance from hub mount = (width ÷ 2) – offset
To calculate the change in the position of the outer side of the wheel, subtract the outer distance from the hub mount for the new wheel from that of the current wheel:
outer wheel position change = current wheel outer distance from hub mount – new wheel inner distance from hub mount
When changing the size of the wheels on a vehicle, there can be a certain amount of error in the speedometer; you can measure this using our speedometer error calculator.
You might also be interested in our tire size calculator to calculate the size of new tires and compare them to your current tires.