Originally Posted by Wordbiker

You mean, barring that it's a:

*Rim which may not meet that tolerance even when new and unbuilt, such as a steel rim with a pronounced seam.

*BMX or Downhill rim that has worse discrepancies in the tires alone, flat spots, gouges, etc. and the owner just wants it to turn in the frame.

*Heavily used, defective or damaged rim that the owner refuses to replace, hence my "good enough" comment.

*Bike with a disc, drum, roller or coaster brake.

*Toy/Department store bike.

It is an imperfect world we live in. Sure, a quality rim for rim or disc brake application that is not damaged not only should be completely round within .5mm tolerance, but should be capable of true to that tolerance or less when built up. At a guess I'd say that constitutes 25% or less of all wheels brought to a shop for truing.