well im regearing from 3.55's to 4.10's and i have 285/75/16's im tryin to figure out how close to stock ratio or gearing ill be... so anyone?

 

Your RPM's will be about 20% higher than they are now.

 

since i suck at math any idea in actual RPM's that will be? im guessing around a thousand rpm?

 

http://4lo.com/calc/gearratio.htm

You have 33" tires. In overdrive at 70, you are turning 1770 rpm. With 4.10's, you would be turning 2045 rpm.

 

To answer your thread question of final drive ratio another way.
In overdrive your final ratio would be .7 times 3.55 = 2.485 for original gearing.
With 4.11 gears it would be............ .7 times 4.11 = 2.877 for new gearing.
If you change tire diameter, it will affect the final RPM vs MPH that you will get.
You should see the final result directly as about the ratio of the difference between the two above final gear ratios plus the tire size change.
Larger diameter tire will tend to put the rolling gearing (actual surface travel distance) back in the direction of the 3.55 gears or somewhere less than 2.877 and greater than 2.485.
You can see the differences in RPM per the same speed when compairing the two setups.
But keep in mind, the speedo won't read accurate (if it ever did) so RPM becomes the better of the two indicators, at seeing the results.
From RPM and final gear ratio and tire size, you can figure MPH without depending on the speedo for accuracy.
As an example, my truck without any kind of changes has been consistant at reading 2 mph 'over' the real ground speed as measured by many different electronic speed signs along the roads.
As a further note, the original gear ratio is also in the PCM program and is sometimes changed by owners who have a custom programmer capabile of doing so.