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Old 01-08-2010, 02:03 PM   #4 (permalink)
Ernie Rogers
Ernie Rogers
 
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Really, what is the Crr$

Quote:
Originally Posted by tasdrouille View Post
Wouldn't that be estimating the Crr, since you are deriving Crr from a bounce test, and not directly measuring RR?

The only valid way I can think of to properly test this is to conduct both bounce tests and proper Crr testing and see if there is a correlation in the results.
Excellent comment, Tas. Really, what is the Crr?

For me, it's a parameter I need to calculate fuel economy. For everyone, we use it to decide which tires give the best mpg, and these two are really the same thing. But, does the standard measurement for Crr fill the need? The fuel economy of a car is highly dependent on the interaction between the road surface and the tire, AND the suspension. There is a lot of bouncing going on in the real situation.

Okay, Tas, back to your point-- validation is very important. I would say, someone should be checking BOTH the accepted method and the bounce test to see how well they correlate with actual fuel economy.

Ernie Rogers
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