I agree with David and always set the rim offset with/to the bike. After initial truing of the wheel/s. With the front, centre the rim to the steering head. With the rear, I always check the final drive chain line, sprocket to sprocket, first, using a taut fine string or hand held laser - it nearly always needs some trimming with appropriate spacer adjustment/ shims etc. Then with the fuel tank removed (and ideally the rear mudguard also) and a taut string fixed at the steering head/ laser, eye to the rear wheel, down the centre of the top tube of the frame and adjust offset until the rim centres to the top tube. Both wheels will automatically be in line, which is what you are after.