How To Measure Wheel Rim Offset

You will want to measure from the barrel section and not to overall outside width see picture below.

How to measure wheel rim offset. Wheel offset is the distance in millimeters from the center line of the wheel to the mounting surface. Wheel offset the offset of a wheel is the distance from the hub mounting surface to the center line of the wheel. To compute the centerline measure the distance from the outboard to the inboard flange which is the width of the wheel let us say that the width is eight. Lay your ruler across the inboard flange.

Divide the measurement by 2 to find the center line. Wheel centerline outboard flange to inboard flange measurement divided by 2 once you have these measurements you need to subtract the wheel centerline from wheel backspace to get the offset. Take the floor to straight edge measurement and halve to get the measurement for the centerline of the tire. If you divide it by two this means that the centerline is four.

If backspace is less than the wheel centerline the offset is negative if backspace is greater than the wheel centerline the offset is positive. You then subtract the distance from the hub to half the width of the rims. Wheel width measuring the wheel width is similar to measuring the diameter. To measure backspace you can just use a ruler or measuring tape to find the distance from the rear of the wheel well to the tire.

To measure offset you must measure the width of the rims and then measure the distance from the hub to the outside of the rims. Unlike a rims true width offset refers to the center of a wheel from the outside of each lip. This is done by laying the wheel face down so the back is facing up towards you. If the mounting surface is closer to the face of the wheel it is known to have a positive offset and if the mounting point is closer to the inside of the wheel it has a negative offset.

Using the straight edge as an indicator for the back of the wheel you will measure the backspacing which is distance from the back of the wheel to the back pad the part of the wheel that mounts up to the vehicle hub. Measure the width of the wheel from outside lip to outside lip. Determine the wheel backspace measurement. For example if the measurement was 244 mm 96 in then the center line measurement is 122 mm 48 in.

You will need this number to calculate the offset. To compute the wheel offset all that you have to do is to subtract the centerline from the backspace. To measure backspacing or offset youll lay the wheel face down and lay a straight edge across the back of the wheel.