Originally Posted by nthinuf

To run taller/wider tires, you generally want to run less backspace (move the rims out). Whether you buy new rims with less backspace, or add spacers to run less effective backspace, the 'stress' on parts should be about the same. The wheel bearings aren't really going to know the difference, right?

If you are asking 'Are wheel spacers safe?', try this thread:
https://www.jk-forum.com/forums/modi...s-safe-317080/

If you are asking specifically about RC spacers vs any other mfg, try this one:
https://www.jk-forum.com/forums/modi...safety-130315/

For gearing, there are about a bajillion threads to read through for opinions. Depends on which engine you have, and which transmission, and where you live, and how you drive, and what your expectations are, and ...

Programming, yes you will want to. Aev procal and superchips flashcal are the most popular programers. If you want a little extra hp as well as the programming, superchips flashpaq and diablosport intune I think are the most popular tuners.

Originally Posted by DJ1

Yeah you'll need something like an AEV Procal or other similar device to reprogram in the different size tire....

Originally Posted by sa29560

Just makes some room to steer!

You could fit 35s on 2.5. That's what I'm at as well as many others.

Originally Posted by rugahrahj

This is something I could program myself with the procal right?

Originally Posted by nthinuf

Yes, any of the programmers/tuners will let you adjust the tire size and gear ratio. The procal uses dipswitches, the flashcal has a screen and is internet update-able. The procal will let you adjust tire psi settings and shut the tpms system off completely. The flashcal will not adjust psi any more, it will only let you turn it off.