Originally Posted by WorldWind
Is it a front or a rear wheel?
To one side caliper, it should be the same for a front, but different for a rear, because of the dish.
For a rear set the caliper width to the depth of your cassette dish plus the rim width and then when you flip the wheel use the other side caliper.
Keep in mind that a rims cross section can vary in width at different points around it’s circumference by a small amount.
A rim should be centered between the dropouts, chainstays, and seatstays. Makes no difference if the wheel is a front or a rear. On a rear wheel the hub flanges are asymetrical to make room for the cogset, but the rim is centered.