Somebody said it best - HERE WE GO AGAIN.... The actual gear ratio has
nothing to do with the size of tires!!!!!!! The actual gear ratio is
controlled 100% by the gears which are installed in the rearend. There is a
phenomena, which many have called the "effective" gear ratio, which is
affected by the tire size. This phenomena can be expressed as an effective
gear ratio, considering the actual gear ratio and tire size, but it must be
measured relative to some standard value. (A good standard would be the
as-delivered condition of the truck.)
I have actually made an Excel spreadsheet to study different options and
combinations of ACTUAL gear ratios and tire sizes, which will calculate an
EFFECTIVE gear ratio, as compared to the stock setup on the truck. As a
learning exercise, I would encourage others to do the same, in order to
better understand the relationships between tires, gears, and rears.
As a side note, if you are going to do the tire rotation/count the driveshaft
rotations exercise, it is much more accurate to rotate the tire multiple
times (10 is a good number), count the driveshaft rotations, and then divide
by the number of tire rotations. This removes much of the error associated
with only rotating the tire one time.
Steve Menendez- P.E.
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:15:45 EDT