Quote:
Originally Posted by Vekke
I have always thought that tire companies do almost all the R&D work on popular sizes. Then they will just scale it down to other sizes and widths and say that they are the same. Maybe that test proves my estimations true?
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While I can confirm that tire manufacturers develop tires in a couple of sizes, then scale them up and down as appropriate, I think what the test says is that there is something else going on and you can't compare the rolling resistance of tires of different sizes.
I'm surprised no one has posted this in this thread:
http://www.energy.ca.gov/transportat...%20Testing.pdf
It's a study done for the California Energy Commission. Not only does it test various tires for rolling resistance, it also studies the effect tire size has on rolling resistance. This confirms that different sizes of otherwise identical tires have different values - enough that you can't reliably compare tires of different sizes.
I ran a regression analysis on the data and developed an equation so the differences in tire size could be compared, but the R-squared value wasn't all that great: 66%