A wheel's offset describes its position on the rotor. If a wheel has a positive offset, as many front-wheel drive vehicles do, the hub mounts onto a surface outside the wheel's centerline. If it has a negative offset, it has the opposite configuration--- the hub mounts onto a surface on the brake side of the centerline. Your wheel's specifications usually list its offset. If they do not, you can read the offset by measuring the wheel manually.
Measure the wheel's width. This value exceeds the wheel's advertised width, which measures just the distance between its flanges.
Divide your answer by two to find the wheel's centerline. If the width equals 12 inches then 12 divided by two equals 6 inches.
Measure how much distance separates the wheel's hub-mounting surface from its inboard flange.
Subtract the centerline from this answer. If the hub-mounting surface is 4 inches from the inboard flange then four minus six equals minus two. This answer is the wheel's offset.
