I have a 2005 Jeep Rubicon. I am still running the stock 245/75/16s and in a week or so my 285/75/16s will be here, im going to swap them right in... anyways im needing to know how i need to adjust my speedo and or odo. do i need a new speedo gear or do i need to go with an electronic adjustment?  

Update the computer.  

heres what I found since I already told ya I didn't know... valuable info to me also cause I'm about to goto 5.13 gears with my 34" trXus m/t's

aparently the computer can be set for tires up to 35", gear changes on the other hand need to be calculated to a tire size w/4.10 gear to fool the computer in the rubicon

superlift truspeed and jet accu-speed have elctronic boxes that correct it plus there is this..
signal interface


 

is this the only way to do this? i think i have heard hypertech or something will do different tire sizes. what does updating the comp have over a speedo gear?  

Rubicons (241OR TC) does not have a speedo gear. It just has a square wave signal generator.

So, you either adjust the signal generator, which is what the Superlift box does, or you change the way the computer interprets the square wave; update the computer.

The dealer can update the computer, and so can some of the aftermarket programmer/chips.

I've "heard" that some of the programmer/chips have the capability to adjust the algorithm and not just the gear/tire combo. This is what Mud is talking about. I've "heard" the same thing.  

there was some talk of dealers not being able to adjust is also cause theres no antilock braking systen on the rubi..  

according to this months 4 wheel drive & sport utility magazine 4x forums november 2008 issue page 10, the truspeed is the one ya want, at least thats the recomendation...

there's also a pro comp accu pro that'll correct it up to 5.13 gear ratio's

apparently there is a question as to wheather the jet or hypertec units will work...