After installing 315/70/17 BFG All Terrains a few months ago on our Jeep, I have noticed a slight decrease in performance and transmission shifting behavior.
I do not drive the Jeep daily, so my experiences with it are on a weekend only basis (wife's daily driver).
1) After installing the larger tire, the speedometer was reading slow
2) After installing the larger tire, the odometer was reading slow
3) After installing the larger tire, the Lie-O-Meter was reading an average of 13 mpg.
4) After installing the larger tire, the "estimated fuel range guage" was reading extremely low, to the point that with a 1/4 tank of fuel left it was reading "lo fuel"
5) After installing the larger tire, the tires had to be inflated to approx 40psi to not trip the tpms idiot light. The overinflation resulted in the center of the tread makeing the majority of contact with the road. This would eventually lead to premature tire wear.
I decided I needed to correct the above issues and had settled on an AEV Procal, or the Superchips flashcal. They both seemed easy enough to operate, would cure all of my symptoms, and were similar in price.
I favored the display screen on the flashcal over the dip switches on the AEV, but was open to either. I went to my go-to place for ordering things, which is Amazon.com as I am a prime member.
Amazon offered only the flashcal, so this is what I decided to order. It was $159 with free shipping, but I opted to splurge on the "get it tomorrow" rush shipping that was $3 more. I placed my order on Thursday at 4:50 pm, and it was delivered via UPS at 2:30 the next day. Amazons freaky fast shipping never ceases to amaze me.
Upon opening the package, there was:
-the flashcal unit
-Some superchips decals that I will not be sticking on the Jeep.
-An instruction Manual
-A USB cord
The instruction manual advises to update the unit via a free download on the superchips website using their "Spark Software Updater".
I downloaded the program and plugged the unit into my computer. The computer could not find the driver, nor could it recognize the Flashcal. I realized that my lovely work computer was blocking the automatic driver download so I set off to do it on my PC.
On my PC the program quickly recognized the flashcal, and all was well. It's not the most advanced software, but it works so I have no complaints. Upon plugging it in, I was told that it was already up to date, and I could install two additional programs.
1) The Offroad TPMS Program (which i believe changes the TPMS threshold to zero) This one was free, so after entering my name and email it downloaded to my device.
2) The Flashpaq tuning software. $179 and includes the performance tunes. I did not download this.
I then went to the garage an plugged the unit into the Jeep. Easy enough. It goes through its boot process, and then displays the Jeep logo before bringing me to the main menu.
Main Menu has the following-
Tuner Info and Settings
I went in to the vehicle functions where after a few pushes of the buttons and some on/off movements of the ignition key, my tuning was complete.
I was able to set the TPMS to its "Offroad" Setting that brings the PSI threshhold down to zero.
I was able to set my tire size in 1/4" increments. I set mine to 33.25 after measuring the BFGs.
I was able to turn my fog lights on while high beams are on.
I was able to set the acc timeout (radio) to 10 mins after the ignition is shut off. (good for tailgating, camping, driveway music, ect)
All this was done in about 10 minutes time. After completion, I toyed around with the high idle feature that was pretty neat. Not sure if I'll ever use it on the Jeep since you have to have the Flashcal with you and plugged in, but neat none the less.
I then did the "chalk test" or "water test to identify the best psi to run in the tires. I came to 22psi, to give even treadwear. Later that evening we took the Jeep for a drive to meet up with family for dinner plans. Approx 45 mile round trip.
I immediately noticed the the Jeep no longer had the tendency to "lug" in a gear too low. Downshifting and gear hunting on slight grade in road was now nonexistant. Lie O Meter was averaging 19.5 mpg with my light foot, and speedometer seemed accurate (I will later test by gps). TPMS idiot light was also off.
My overall review is that this was money well spent, simply on the shift characteristics alone. It is also nice to have the tires inlfated to a proper psi, giving me a little piece of mind that the BFGs will have to longest treadlife possible. I would reccommend this product to any folks looking to solve the issues that I was experienceing.
And a poser shot...