So, why in the hell would they use the 3.92s on the R/T..... Cuz of the
low profile tire???? If the shaft is turning faster than the axle, then
darn I will never get down that stupid track....
Jason
1/29/99 5:36 PM
-----Original Message-----
From: Jetmugg@aol.com [SMTP:Jetmugg@aol.com]
Sent: Friday, January 29, 1999 4:43 PM
To: dakota-truck@buffnet.net
Subject: DML: Re: Tire size/ effective gear ratio.
Okay - here goes. Smaller tires (short sidewall) is
like putting in "deeper"
gears. This would be like changing from 3.90's to 4.10's.
Bigger (taller)
tires are like putting in "taller" gears, like going from 3.90's
to 3.55's.
Sometimes the description of the gears can get
confusing, because
NUMERICALLY lower gears (like 3.23's) are not what we think of
when we think
of "lower" gears. Likewise, NUMERICALLY higher gears (like
4.10's) are not
what many people would think of when someone says "higher"
gears.
We have to uderstand the relationship between driveshaft
rpm and the distance
that the truck travels for each driveshaft revolution in order
to discuss the
"effective" ratio, which includes the gear ratio and tire size.
With 4.10's,
the driveshaft has to turn 4.1 times for every time the axle
turns once. With
a 3.55 set of gears, the driveshaft has to make 3.55 revolutions
in order for
the axle to turn 1 revolution. Now, for the same set of 3.55's,
if you have a
26" tall tire, the truck will move about 82" forward for each
axle revolution.
However, if you have a 30" tall tire, the truck will move
forward
approximately 93" for each axle revolution. In this case, going
from 26"
tires to 30" tires would be like installing NUMERICALLY lower
gears, which are
sometimes called "taller" gears. In this particular case, if
the 3.55's and
26" tires were the "stock" size (which I realize they are not),
then switching
to the 30" tires would give an "effective" ratio of
approximately 3.10,
compared to the "stock" setup.
I hope this helps a little, although I realize it may
still be a bit
confusing.
Steve M.
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