Quote:
Originally Posted by joedls
Since we're being nitpicky, your math is a little off. Here's how I calculated it.
MPH= ((RPM/(rear gear ratio*trans gear ratio))*60)/tire revs per mile
RPM = 6000
Rear Gear = 3.73
Trans gear ratio = 1
Tire revs per mile = 720.49
MPH = 133.95708
Thus my earlier posting that it would be ~134 MPH.
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My sheet does three things a little differently. It calculates circumference exactly on input tire size. A 275/60x15 is slightly less than 28 inches. Additionally for reasons I can't remember and forgot were in there it has built in corrections altering the revs per mile and revs through the transmission. Hence the reduction from your completely accurate pure calculation. I can alter my sheet to remove these built-in corrections and we'll come out to the same numbers exactly. But this would be a totally idealized, perfect circumference, no slop kinda situation. I suspect my sheet may model reality a little more closely, but I certainly can't give you the logical proof for the constants that are used. There, aren't you glad you asked?