An interesting discussion here from CAT scale engineers seems to indicate that, to my surprise, CAT scales are reasonably accurate over their entire range (200,000 pounds!) Apparently they are calibrated at a number of points over their range, rather than just calibrated at the top, and then dividing the range into (assumed equal) increments. Be cautious in reading the discussion, though. The writer makes the common error of confusing accuray with resolution. They are not at all the same thing.
http://fifthwheelst.com/commercial-t...ghing-rvs.html
Bill