Jeep-Junkie34

Would I have to change anything or install any chips for those If I'd install a 4" lift with 35s?

Freewill

A Procal will let you tell the ECU about your new tire size so the speedo will read right. Just Google Procal or search it up here.

ronjenx

And don't just plug in what you think is the tire diameter.


An easy and accurate way to measure tire diameter:
Stick a piece of chalk in the tread.
Move the Jeep until there are two chalk marks on the pavement.
Measure between the chalk marks.
Divide the measurement by 3.1416.
That's your tire diameter.
It removes the variables encountered with other methods.

r3cluse

I heart pi.

Jeep-Junkie34

Are those required? If not then I could sacrifice my speedo being off by a few mph.

golfer97

If you have an auto, your shift points will be off and it will feel different with acceleration. Besides not knowing how many true miles on your jeep, I think you want your transmission to be shifting properly. If you a manual, it's not as important but you will still have a messed up mileage number over time.

r3cluse

It's worth the investment, your speedometer will be off by 5-7mph slower so you'll be over the speed limit. Depending on the cops in your neighborhood it may not be a big deal. On base they frown on doing 30 in a 25 especially when they lower the speed limit due to road conditions. The AEV ProCal is pretty handy to have around.

Jeep-Junkie34

Is there any write ups or people who have already done this? & what's the average cost? Does the ProCal do the odometer too?

ronjenx

The only write-up you will need is the instructions that come with the ProCal.

The ProCal doesn't do anything with the speedometer or the odometer.
It just tells the JK's computer the tire size, based on your input.
From that information, the computer will display the correct speed and distance.

HogHoden

Tons of people have used the ProCal on here.

The price is $150 anywhere you get it. Several vendors on here sell them. There are usually a few in the for sale forum for a little less if you want a used one (but they can only be used on one Jeep at a time).

It also has some other features that are nice, like DRL settings, high idle for winching, and TPMS alarm adjustments so you can run proper PSI in your 35's without the low tire pressure light on the dash.