37x12.50s + Procal = Surprised by mileage

[14RAM4X4]

I'd been rolling 295/65r20s Nitto Trail Grapplers for about a year. According to Nitto's website they are almost half an inch taller than their 35x12.50s. The evic told me I was averaging about 11.7 - 12.0 mpg. Hand calc I was averaging about 11.5 mpg. At the time I had no correction for the increase in tire size.

I moved up to 37x12.50s recently and evic dropped to 11.0 - 11.4 mpg. Hand calc was about 10.8.... Then I ordered and installed the AEV Ram Procal.

2 tanks of gas later, the evic is reading 13.6. Last tank evic showed 14.0 and hand calc I show 12.7 mpg. I think the 200 mile hwy trip skewed the evic #s a bit. Trip odometer daily driving evic is at 13.2 - 13.4 and my all in town and hwy daily commute I hand calc 12.4.

Not great numbers, but definitely better than the 10.8 I was averaging before the procal. I set the procal at 36" tires and it's pretty accurate to GPS speed. I have my tires at 55 psi and might drop them to 50 psi.

 

[matt.davidson09]

Nice. What model do you have and what are your gears?


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[14RAM4X4]

Nice. What model do you have and what are your gears?

Tradesman CC short bed with 3.73 gears

 

[Phil21502]

How does the procal work at adjusting tpms pressures?

 

[14RAM4X4]

How does the procal work at adjusting tpms pressures?

It only changes the setting in one place. But you still need to go to the dealer to get the truck flashed to stop giving you the low pressure light on the dash.

It's been a 2 step process for our newer trucks

 

[Phil21502]

Yeah my dealer says they can't do it even if I buy the pro cal. Pain in the butt

 

[G. Mcpherson]

Check with 4x4x4door here in the TPMS Thread here. I used his Autel Maxis Tool.

 

[BIG TRUK]

I recently got the procal.
It was super easy to change the tire pressure and tire size.
The dealer did have to update the computer but with the instructions provided by procal it was also easily done.
The dealer didnt charge me, but i did buy the truck from them about 6 weeks prior.

Chris

 

[4x4x4door]

I recently got the procal.
It was super easy to change the tire pressure and tire size.
The dealer did have to update the computer but with the instructions provided by procal it was also easily done.
The dealer didnt charge me, but i did buy the truck from them about 6 weeks prior.

Chris

Wow, you're fortunate 2-fold. Most dealers have stopped doing the RFH update and if they do it's never free. Heck, many have now started to charge a fee for the 4-digit PIN.

 

[14RAM4X4]

Just a little follow up.

Put about 5K miles since using the Procal to correct for tire size. I stayed at the 13 - 13.6 mpg mark for a good while. Then my son's basketball season started. Since then, I've been in more of a rush most days. Hovering about 11.5 - 12.2. Man, that Hemi Foot makes a good deal of difference!!! I've gotten the EVIC down to around 10.2 mpg too. These are EVIC #'s, but since I corrected for tire size, my evic is only about .5 - .75 mpg off my hand calculations.

 

[Odin]

This is interesting. I received my procal on Thur and when I followed the instructions for measuring I was doing roughly 8mph less than what I was actually doing. Today I adjusted the tire size several times trying to get my mph to match GPS and all of a sudden the module stopped working with my truck so I'm stuck.

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[14RAM4X4]

This is interesting. I received my procal on Thur and when I followed the instructions for measuring I was doing roughly 8mph less than what I was actually doing. Today I adjusted the tire size several times trying to get my mph to match GPS and all of a sudden the module stopped working with my truck so I'm stuck.

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Any updates? That sux. I haven't had any issues.... knock on wood!
Did you try setting it back to stock? Each time I use it, I go thru the whole process, but I turn the truck completely off and remove the key between adjusting settings.

 

[Odin]

Any updates? That sux. I haven't had any issues.... knock on wood!
Did you try setting it back to stock? Each time I use it, I go thru the whole process, but I turn the truck completely off and remove the key between adjusting settings.

I actually ended up having a HUGE problem. There were a bunch of diagnostic trouble codes stored in the computer that the Procal stopped working all together. Wouldn't reset to factory or anything. I was stuck with tire size at like 36. Ended up having to go to he dealership for them to clear all the codes. After that the Procal started working again. The imperial size conversion left me with 34.6 so I had to play a round within the 34-35 range. It's funny how much .25 can really change the mph. At 34-34.50 I was anywhere from 3-4 mph slower. At 34.75 I was within 1 mph and at 35 I was roughly 3 mph faster.

So the lesson I learned, their instructions for measuring don't work for me. Lol.

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[Lifted2wd]

Does the ProCal only go to 36"? I also have 37's and was looking at this set up. Might look into a full programmer. I have the ProCal on my wifes jeep and it worked amazing

 

[Odin]

Does the ProCal only go to 36"? I also have 37's and was looking at this set up. Might look into a full programmer. I have the ProCal on my wifes jeep and it worked amazing

No, it goes up to 48

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