here is another method that you can do and not even jack it up.
Tools needed
A flat surface
Masking tape
6 feet of string or more
Chalk (for marking)
Simple five steps
Park your rig on a flat surface.
Tape one end of the string to the bottom (6 o’clock) of the rear drive shaft. Using a clock method to determine location, bottom would be 6 o’clock, and the top would be 12 o’clock.
Mark the rear tire where it touches the ground.
Now push your rig forward so that the tire make one full rotation or two (divide sting count by two if you do two)
Look at string on the drive shaft.
The string will wrap around the drive shaft and the amount of wrap it has will tell you roughly what gear ratio you got.
Example:
If the string is wrapped around the drive shaft 3 times and a little more but not a 1/4 more then you have the 3.07 to 1 gear ratio
If the string is wrapped around the drive shaft 3 ½ times than you have the 3.50 to 1 gear ratio
If you got the string wrapped around 4 ¼ times than it will most likely be 4.11 to 1 gear ratio.
