rim offset ?

[cam400ex]

how do you measre and where for the offset on a rim? probably a stupid question but i'm not sure thanks

[Colby@C&DRacing]

From the inside lip of the rim ( were the tire sits) to the center on the rim were the two halves are welded together. Measure each direction and this will give you the offset.

[300ex73]

I thought it was from the inside of the wheel to the hub side of the wheel center.