|08-31-2013 12:59 PM|
|08-31-2013 09:38 AM|
|X50ARM||I measured the center of the hub to ground under load and multiplied by 2. This worked good for mine.|
|08-30-2013 09:39 PM|
|jmb6420||I have 285/70's and had to leave my speedo stock to get the correct reading. I marked the tire with a paint stick, let the jeep roll, measured, but in the results and the speedo was way off. Leaving it stock and checking with GPS the speedo is within 1 mph at 60 mph. I just left it there and chalked it up to something I was doing wrong, but the more I read about it, the more I'm convinced that the procal is inaccurate when I comes to tire size calculations. All the other features work great.|
|08-30-2013 02:49 PM|
I don't know about that.. Either way guess of you are happy with it then that is all that matters. I also had 4.88 installed have to say I was very disappointed, seemed almost weaker that the 3.73 I had but with correct tire size in it really made a difference.
|08-30-2013 02:47 PM|
|HAFICON||OK I went and drove it and worked it down 1/4 inch at a time stop reprogramed it and drove again and behold the perfect setting...... 33.75.. Speedometer as per 2 GPS apps is dead on.. But thanks for the replies nice to be backed up by other users.|
|08-30-2013 09:17 AM|
|Xena1||I wonder if you read the chart incorrectly? I get tabs dduuddudu.|
|08-30-2013 09:07 AM|
|Xena1||Most 315/70/17 tires have 604 revs per mile. Doing the math 63360/604=104.90 divided by 3.14 = 33.40. To account for wear the procal setting should be 33.25.|
|08-30-2013 08:03 AM|
|ave8er||I put 315's on my '14 and have not yet installed a ProCal. It shifted badly right after I did the install and after a couple hundred miles it shifts fine now. Maybe the transmission control unit learns all by itself?|
|08-29-2013 11:34 PM|
|08-29-2013 10:22 PM|
|08-29-2013 10:11 PM|
|08-29-2013 09:30 PM|
Question for the users here. So I am trying to set my tire size into the computer, I had 315/70/17 which come out to be about 34.4ish but following AEv's instructions you measure the tire size under normal load.
So that for me with current tire pressure is just over 33". If I plug that size into the AEV Pro Cal then speedometer is off by about 10mph, and shift points are way off so much that it wont shift out of 2nd till 5200RPM.
Now if I plug in the size for 34.75 the speedometer is off by 1-2 mph and the shift points are pretty good.
How did you do yours how does it work?