# Math question

• posted on October 24, 2003, 6:40 am
Ok here it goes, knowing your tire size, your engine rpm, your trans drive gear, and your final rear end drive gear, how do you throw those together to
get your final potential speed?
I tried rpm/trans gear/drive gear*tire size in inches/the number of inches in a mile* 60(the number of minutes in an hour since its rpM). What am I doing wrong, or not seeing right?
I found calculators on the internet for it which work great, but I want to be able to do the math myself, without having to run for a computer. \$5.00 Solar crappy calulator, maybe.
Brian
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• posted on October 24, 2003, 2:42 pm
what website did you use? I don't know the formula, but maybe we can jack it from the JS in their pages :-)
Travis

to
\$5.00
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• posted on October 24, 2003, 9:08 pm

drive
together
inches
I
to
I can send you a Excel spread sheet and you can steal it from there.
Al
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• posted on October 25, 2003, 2:14 am

it s RPM= MPH x GR x FTR x 336 / TD
RPM = well RPM MPH = well MPH you want to see the rpm at GR = gear ratio FTR = final trans ratio if you are going to using overdrive 336 = magic number for it to work out right TD = tire diamter
moderator at www.fl-thirdgen.org
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• posted on October 25, 2003, 3:39 am
MPH=Tire Radius/168 * RPM/Gear Ratio RPM8 * Gear Ratio * MPH/Tire Radius Gear Ratio= Tire Radius * RPM/168/MPH Tire Radius8 * MPH * Gear Ratio/RPM
Bird79 1979 Firebird Esprit 1973 455 YC
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• posted on October 26, 2003, 1:44 am
Dang, thanks for all the replys. :)
Brian

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• posted on October 28, 2003, 9:54 am
On Thu, 23 Oct 2003 23:40:25 -0700

Make sure the tyre size is the tyre's circumfence and NOT its diameter or radius. If you use a radius, you will need an additional 2 * PI in there.
ALSO: tyres slip at high speed. And I believe that they slip a lot. Over 10% I believe.
Bram
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• posted on November 1, 2003, 2:56 am
Now let me get this straight, you measure the outside diameter of your tire, then multiply by the girth of your girlfriend's ass, minus her squat height, then figure-in her heffer donut needs for a month, and finally add how big her gut is after she japped you with 2 or 3 brat kids-- and that gives you the size of your blue balls at this point, right?
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