This just dawned on me today. It has been highly suggested to me before that I need to buy the procal or other tuners to adjust my tire size (now running 305/70 r17). When I purchased my 2012 jk it had the pizza cutter wheels and tires and I bargained my way to have them upgraded my wheels and tires to the Sahara polished 7 spoke. My questions is the procal (or any other tuner) going to make a noticeable difference in anything other than my speedometer? I can't justify spending $150 to only get a more accurate speedometer. I'm assuming that my settings are most likely set to the stock pizza cutter settings if that helps.



ps. I will admit that I am not mechanically gifted at all and don't understand half of the really technical stuff on here, but I'm trying to absorb as much information as possible.

 

You prob just got an upgrades rim package but the tire it self is the same size. Once you go to 33" or 35" you would want to get a ProCal to fix the speedo. If you don't mind your speed being wrong then I guess you wouldn't really need it. But of you think 150$ is a lot to spend just wait until you want to do something else to your jeep...150$ item is jeep in the jeep world.

 

The tires were definitely not the same size. I went from the cheapest jk sport rims and tires to the 7 spoke polished wheels and Bridgestone dueler a/t's ~31". Would my shift points change at all or is it in any way harmful the way I am running it now? Also, would I get better gas mileage?

 

I have an 07 JKU Sahara with 4.10s. My avg highway mpgs was about 18mi/gal with stock wheels/tires. I upgraded last week to Pro Comp MTs 35x12.5 on 15x10 PC 152s. My mpgs went down to about 13 highway. I bought a ProCal yesterday and tuned the ECU to the new tire size, and found that the JK is smoother and my mpgs are sitting about 16mi/gal highway. I think it will pay for itself in the next couple of months considering the price of gas these days. It certainly helps with shifting points as well, and can only benefit from that.

 

Thank you very much! That is the reply I was hoping for.

 

I agree with this, had the same result when going to 35's. I drove it for 5 months or so without the Procal and then bought it. Definitely a noticeable difference with the shift points, much smoother now.

However, for factory wheels, I really don't think you're going to see much of a difference. The person above and myself run 35's which is a big difference over the stock wheels. When you compare a factory Sahara or Rubicon wheels to the base model wheels, it's really not that big of a jump.

 

Just out of curiousity... Why wouldn't I see as much of a difference just because my wheels are stock (2013 rubis) even though my tires are 305s?

 

My bad -- I didn't realize you were saying factory wheels with 305's. I was thinking the base 16's vs factory Sahara 18"...

Yeah, the 305's are roughly 33-34". You would definitely see a difference.

 

Haha good because I purchased it before your post.

 

Also would like to ask, how easy was it to actually program? Is it pretty idiot proof or what are your opinions on it?