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 the Inner Clearance Change
When changing the size of the wheel on a vehicle the clearance on the inside of the wheel will change. Use the following formulas to calculate how much that clearance changes with the new wheel.
Start by finding the distance between the inner edge of the wheel and the hub mount for each tire:
inner distance from hub mount = (width ÷ 2) + offset
Then calculate the change of the inner clearance by subtracting the inner distance from hub mount for the new tire from the current tire:
inner clearance change = current – new
Often the wheel width will be measured in inches, but the offset is measured in millimeters. Ensure that all of the dimensions in the formulas are in millimeters. Try using our inches to millimeter conversion calculator to convert inches to millimeters.
How to Calculate the Outer Wheel Position Change
The outer position of the wheel will also change if the width or offset of the new wheel changes. Use the following formulas to find the change to the outer position of the wheel.
Start by finding the distance between the outer edge of the wheel and the hub mount for each tire:
outer distance from hub mount = (width ÷ 2) – offset
To calculate the change of the outer position, subtract the outer distance from hub mount for the new tire from the current tire:
outer position change = current – new
When changing the size of the wheels on a vehicle there will be a certain amount of error in the speedometer, you can measure that using our speedometer error calculator.
You might also be interested in our tire comparison calculator to compare the tire change needed when changing the size of the wheels.