Nothing to do with trig. Just good ole fashioned geometry. The difference
around the outside of the tire is called the circumference. Circumference =
diameter X pi. The tire revolutions per mile is the number of times the
tire rolls the length of the circumference. If you have a 32" tire you are
right in your calculations. That percentage is a whopping 9.3%. The next
time you calculate your mileage, multiply the mileage your odometer says
you've gone by 9.3% and add that figure to the total because that's how far
you've actually gone. Divide that by the number of gallons of gas you used
for your MPG. This all presumes the dealer flashed your CABS to 689.
Ron
00 PB SLT QC 4X2 5.9 46RE 3.92 LSD
For modifications see my DML Profile (URL follows)
http://www.twistedbits.net/WWWProfile/dakota/Kw9pV1EkFeOYY
-----Original Message-----
From: owner-dakota-truck@buffnet.net
[mailto:owner-dakota-truck@buffnet.net]On Behalf Of Chris Ryan
Sent: Wednesday, April 18, 2001 2:40 PM
To: dakota-truck@buffnet.net
Subject: DML: RE: Revolutions per mile, CABS setting? Ron Wong?
Original Message:
Date: Tue, 17 Apr 2001 22:43:49 -0700
From: "Ronald Wong" <ron-wong@home.com>
Subject: DML: RE: RE: Revolutions per mile, CABS setting? Ron Wong?
I guess I could have expounded on that. 689 rpm = 689 X 31 X pi
(3.14159) =
67101.22 inches. There are 63360 inches per mile. That means you
actually
travel 3741.22 inches more than is indicated by your vehicle. That's a
5.9%
difference.
Ron
My Trig is a little rusty. Why are you multiplying by pi? I assumed 689
rpm x 31" = 21359, but that doesn't equal a mile. So if that's the
correct equation if I input my 32" tire I should get an accurate
reading. 689 x 32" x pi = 69265.78, which would be 5905.78" more per
mile I'm racking up. Is that correct?
-- Chris
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