i have a 2012 rubicon unlimited and just put on 295 70 17 nitto trail grapplers, i'm running 30psi and measured the tires to 32.75, so i set the tpms and tire size and now my speedo is reading about 5mph faster than i'm really going. is this normal? when the tire size was at the factory specs it seemed to be about 1 mph off. anyone have any experience to chime in. does tire size affect transmission shifting?

 

Not normal-double check those switch positions on the procal-sometimes hard to get perfect measurement but you should have been closer than that. Almost sounds like the setting did not take.

 

I did mine the other day and didn't have the key turned forward into the right spot, I had it at the first click and not the second. I took off down the road and had no speedometer at all. I am just assuming I measured mine correctly, haven't been able to check it yet.

 

I just went through this same thing last week.

My tires actually measure 32.1" tall while on the Jeep. So, I put 32.25" into the ProCal. Speedo too fast. Tried 32.00", still too fast. 31.75" in the ProCal... still a little too fast.

Ended up having to set my ProCal to 31.50" which is over a full half-inch shorter than the tires really are, and now my speedo is close enough that I'm happy with it.

Just play around until you get it spot-on verified by reliable GPS.

 

does the tire size have anything to do with transmission shift points, i read somewhere that it did. also is the correct sequence for doing a recal: 1. turn key to on(position right before ignition). 2. plug procal in and get two honks, unplug procal, turn key to off. also when you guys are doing these recal's do you get the honk pretty much instantaneously as you plug the procal in?

 

From my understanding the AEV ProCal does not work with the 2012 CPU yet. I have been told that but have yet to check dirrectly with AEV.
from what I was told Chrysler changed the programing for the new engine and locked out or they are working on getting into the program for them to work. Quadratec has it on website to work with the 2012 but it does not. Only works to 2011.

 

The system resets practically instantaneously. You should hear it honk immediately.


Did you try to change more than 1 setting without cycling the key? The same thing happened to me because I tried to change tire pressure and tire size without turning the jeep off completely.

 

i spoke directly with AEV and they said that it would work with all the functions the procal does excempt the EURO DRL and changing the gear ratios.

 

Normally all car manufacturers have their speedo's measuring a bit higher than the actual speed you are running, i followed the instructions of the procal anc do not mind the speedometer of the car, just try to "feel" the engin !!

Ciao
F

PS
I love the Procal really changed the whole driving of my JK