In a message dated 08/08/2002 3:45:54 PM Central Daylight Time,
mjb@autox.team.net writes:
> Tire Diameter (in) x RPM x 188.5
> Speed (mph) = -------------------------------------------
> final drive ratio x gearbox ratio x 63360
>
> I just have this spreadsheet I wrote up years ago where you plug in a few
> bits of info and you get the chart of speeds in the various gears. I
> haven't
> actually sat down with a calculator and the equation for quite some time.
>
Mark:
We have similar to the above on a spread sheet as well, for the several
different tires sizes and drive trains we run. I am not very secure about
matters mathematical (although I like to multiply), but I am interested. We
normally get our tires from SASCO SPORTS, and the formula they gave us was:
MPH=(((ENGINE RPMs*TIRE DIA.)*0.002975)/(DRIVE RATIO*RING&PINION RATIO))
Seems to be a variation. I've not tried the two equations yet to see if they
come up with a similar answer, but 188.5 divided by 63360 = .002975, so I
guess both would get similar answers.
.
At one time BFG had given me an equation that involved tire revolutions per
mile. I seem to follow the logic on that one a little better, but I've
misplaced the equation.
Bill Dentinger
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