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Old 10-05-2012, 03:59 PM   #236 (permalink)
Arragonis
The PRC.
 
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Posted from another thread so I don't lose it

Quote:
Originally Posted by PaleMelanesian View Post
say your tires are sized 225-65-16

sidewall height = 225 * .65 = 146.25 mm
top and bottom sidewall = 2 * 146.25 = 292.5 mm
both sidewalls in inches = 292.5 * 25.4 = 11.52 in
total tire diameter = 11.52 + 16 (rim) = 27.52 in
tire radius (ft) = 3.14 * 27.52 / 12 = 7.2 ft
revs / mile = 5280 / 7.2 = 733.33

rpm is more useful for mpg than revs/mile.
rpm @ 60 mph = 733.33 * top gear ratio * final drive
Going to have a play with Excel over the weekend.
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