Re: [ihc] RPM, Gearing formula needed

[tsm1@xxxxxxxxx]

> into your mouth.  I hope my e-mail didn't sound wrong.  I read it over a
> couple times, but then I knew how I wanted it to sound.

;) I'm fine.  I've been meaning to update that chart for some time, too -
modify it to work like my RTI formula page, which allows you to update
most of the entries and re-calc.

> You and I do seem to agree that a tire with a 102" circumference will
> travel 102" each revolution.  Yes?  Doesn't matter if it has 5 psi and is
>> squatting down with a 12 inch radius or at 35 psi and  a 16 inch radius.
> As long as it is still round anyway.  If it is flat and ka-thwumping or

I'm a little puzzled on this one.. I agree a tire with a 102"
circumference should travel 102" with each rev.

BUT.. I'm also reminded that drag racers and such are often concerned with
how much their tires EXPAND at speed.  The radius/diameter will stretch as
the tire is spun.  I guess you could explain this as crowning, or
over-inflating.

If you have a 33x12.50 at "correct" pressure and it has a flat footprint,
or less pressure, it'll probably have a fixed circumference.

But air it up well beyond where it should be, and/or spin it fast enough,
and the center of the tire may expand in diameter, making you run on the
center tread, not the outside.  In that case, I think the circumference
changes.

But back to the real-world.. It shouldn't be a determining factor on
deciding to go 3.92 or 4.09 gears.. it's just not that big of a deal. :D

-Tom