It always sort of aggravated me to hear people refer to "Cold Rolled" as though it was a grade, or a reference to a specific alloy. Like Dalee said, that's just a method of finishing the metal. Not all materials are available as cold rolled, but some are, and often the surface finish and roundness, straightness, etc., is good enough to use as is. That's why it is offered. If you plan on machining the OD anyway shouldn't waste money on it. Most materials are also available in other forms considerably cheaper.