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Old 11-20-2010, 01:41 PM   #18 (permalink)
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Darin,I believe that Hucho's book has CdA vs MPG tables/curves for both N.America and European test cycles.Sorry,don't have my book with me.
If one presumed that the Cd was un-changed and only the frontal area went up with wider tires,then the drag relationship would be arithmaic.Say,a 2% increase in frontal area would mean a 2% drag increase.
At 55 mph ( 88 km/h ) mpg would suffer by 1%.
At 70 mph ( 112 km/h ) mpg would suffer by 1.2%.
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