Have a 2014 wrangler unlimited went from stock tires to 35's. Is there any way to calibrate the speedometer? It is about 4-6 mph off depending on the speed.

 

You'll need a programmer like a Procal or Superchip

 

got to have a programmer... if you think its off my 4-6mph...it probably MORE than that... get the Superchips FLASHPAQ or the Trail dash.... it will allow you to tune, change tire size, gears tpms, just to name a few things it will do...
I got 35's about 2 weeks ago and with out the tuner it would SUCK to drive...

 

Programmers - are cheap and have a lot of functions in addition to recalibrating for tire size. - $150-ish (AEV ProCal, Superchips FlashCal)

Tuners - are more expensive, but allow you to add various performance tunes as well, for a small increase in hp/torque. - $300+ (Superchips Flashpaq, DiabloSport InTune, Hypertech, Bullydog, etc)

And then there are the fancy, expensive tuners with nice displays - Up towards $600 (Superchips Traildash, DiabloSport Trinity, etc)

Any of them will calibrate for the tires, you just need to look at them all and decide which extra functions/options you want. There have also been a few hiccups with certain tuners and certain newer years of JK's, so be sure and do some searching on whichever one you like.

 

These guys hit the nail on the head, Programmer like a Procal will get you all squared away.

RK