Quote:
Originally Posted by rmay635703
So what you are saying is that nobody wants to rate the tire so you can tell what affect on fe it will have? ......
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No, I am saying the government has not issued the rules that need to be followed. All the tire manufacturers have agreed that they will follow the rules once they are published, but until they are published ......
Quote:
Originally Posted by rmay635703
....... I would think you would load the tire to 75% of its rating and measure the drag it creates and test the amount of wind drag at a simulated 65mph fender less drive.
Then weight the two measures appropriately to create a drag metric.
One could then subjectively compare a real metric as opposed to one that is likely meaningless.
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It's the issue of meaningless that has prevented the issuance of the rules.
There are some things that the regulations must address:
1) The test: The good news is that pretty much all RR tests correlated to one another, and a single test point (Load/Inflation/Speed) can characterize the RR of a given tire.
2) Comparing test locations: This is bit more difficult, but there is a way to compare tests from different locations - the SRTT (standard Reference Test Tire) - a carefully constructed and carefully stored tire that has very good and stable properties over time. It is used for traction testing, treadwear testing, and other types of testing where the testing conditions might vary, say, with the weather or testing surface.
3) RRF vs RRC - this is a biggie. As explained in an earlier post, NHTSA wants to use RRF and the tire industry wants to use RRC, and the courts have ruled that NHSTA's proposal isn't workable, but NHSTA hasn't agreed to use RRC.
4) How is the data to be presented: A number? A Red/Yellow/Green bar graph? A combination? Something else? That's up to NHSTA to decide - and they haven't.
5) And the problem of tire size needs to be addressed. Ya' see, RR varies according to tire size. Both RRF and RRC are different for otherwise identical, but different sized tires. Do the tire manufacturers need to test every size of every tire line they make? If so, it would take over 3 years working 24/7/365, and nothing else could be tested. Realistically, there aren't enough testing facilities available. So how to handle? This has barely been discussed with no obvious solution in sight.
In the meantime, Congress has been cutting the budget, meaning there just isn't enough money to work on every project - and this one is a low priority. It seems reducing the amount of traffic fatalities is more important.
So if you want the tire manufacturers to publish RR ratings, send a letter to your congressman. Tell him you are willing to pay more in taxes to get this accomplished.