Quote:
Originally Posted by Old Tele man
...actually, Calif CARB is also pushing this effort, but last I heard the Fed's haven't found a consensus between data, realworld, and lab test equipment--ie: can't get reliable, repeatable numbers from different test facilities.
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Ah...., not quite. Here's the scoop.
Because CARB (California Air Resources Board) and CEC (California Energy Commission) were studying rolling resistance based on a request from the California legislature, NHTSA (National Highway Traffic and Safety Administration) which is the federal regulatory group for all ground vehicle - and that would include tires on those vehicles - decided to step in and implement a regulation that would cover the entire US, not just California.
What NHTSA found was that the various tests correlated well, and they could write a simple test procedure that everyone could perform.
They also encountered that different facilities get different results - but those correlated as well, so they only needed to provide a way to do that - and the propsed regulation includes the use of a control tire.
But the biggest obstacle was tire size. RR varies by tire size - both RRF (Rolling Resistance Force) and RRC (Rolling Resistance Coefficient). This meant that a tire line could not be characterized by testing one tire size and publish that to cover all tires in the line. The only way was to test EVERY tire in a line - and all lines of tires. It was estimated that if EVERY testing facility in the world were to test 24/7 it would take 3½ years to complete the testing - and NOTHING ELSE could take place during that time frame - no R&D, no improvement testing, no in-house audits - NOTHING. That was obvious too long.
Nevertheless NHTSA propsed a regulation in Oct 2009.
But NHTSA wanted to use RRF because they felt it would drive people to smaller cars. The tire manufacturers felt the RRC was the way to go, because an unsophisticated buyer would tend to buy tires based on the value and that would drive him to buy tires too small for his car - and that was a safety issue. They proposed using RRC. They appealed to the GAO to have the regulation changed. The GAO reviewed everything and in Feb 2010 ordered NHTSA back to the drawing board.
In the meantime, the Toyota thing came up and that took all the agency's time. At the moment, there is no activity on this issue.
So the problem is 1) how to characterize a tire - RRC or RRF - and 2) how to publish that so the consumer makes an intelligent choice - and 3) how to implement this without tying up all the test facilities.
