Originally Posted by USAF Long
Changing the rear gears will throw the speedometer off. I want to change mine too but I am not messing with it til I get a tuner to take off the top speed limiter. I was going to put nitrous on my truck but if I do that it will just top out at 105 and shut down before I cross the 1/4 mile. Changing the gears I bet you could have the dealer correct the speedometer but the won't take off the speed limiter. The best bet is to do gears and get a tuner. The gears will make the truck much more snappy off the line. I'm thinking 4.10 or even 4.56 in my truck. I tow a huge boat with mine and the extra low end would really help get the boat moving faster off the line. The Hemi pulls it but it takes it a while to get into the power band. 4.56 would be great for me but I dread the fuel economy drop on the highway.
A gear swap on a 4G Ram requires no setting adjustments, and will not throw off the speedo/odo
The speed sensor is in the diff ABS tone ring so only a tire size change requires a re-calibration.
Diablo and Bully Dog tuners are capable of adjusting tire size,
neither have an option for axle ratio changes.