Gravity EPA docs are here.

suyoungman said:

View attachment 29393

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johnse said:

Why does that show an issue date of 04/23/2025 if it's been holding things up?

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johnse said:

Why does that show an issue date of 04/23/2025 if it's been holding things up?

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Elfin said:

That's a much better test. I can quibble a little with the results though. First they're testing an ICE vehicle which is much more affected by wheel/tire weight, they have a difference of 54lb vs. 40lbs from biggest to smallest. It's too bad they didn't measure highway effficiency (which should not be be affected by wheel weight.) Second the tire performance is very different even though they're all the same model tire.
"We say that the tires were nearly the same because the 15-, 16-, and 17-inchers have a lower speed rating (V, or a top speed up to 149 mph) than the 18- and 19-inch tires’ W-rating (up to 168 mph)."
The V rated tires got 0.83g,.85g,0.85g and 23.3mpg,22.9mph, 22.8mpg
The W rated tire got 0.89g,0.88g and 21.9mpg, 21.1mpg
It seems that there's a significant difference in the tire compound and the stickier tires get worse efficiency.

Maybe we can compromise and agree that larger diameter wheels are usually less efficient primarily because of the design choices made for larger diameter tires?

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