From what I understand dealers can only go up to 32, the largest stock size. You will need an aftermarket programer for anything above that. My 35's penciled out at 34.5, measuered at 34 and I programed them at 33.25 to get the speedometer and odometer correct with my GPS. If you want it exact you will need to have a programer and fine tune it or it will be off.

 

I'm going with the AEV Procal. My dealer wants over $65.00 to do it.

For $129.00 + shipping I can do it and more myself.

This is just like when service departments want to charge to read engine codes. You can just about buy your own reader for what they charge for one reading.

 

I paid $80.00 to my dealer and it is still off 10%. I have a 2007 wrangler X 2 dr with the 18 inch 255/70R 18. they were a option on the sahara. I love my gas miles.

 

My dealer told me the same as some one above mentioed they can not program it for any thing bigger than 33" tires,so for 24 bucks mine is still out

 

I used the Procal.. took 2 seconds to program for 35's. Also has a bunch of other features. I checked the Procal settings VS my GPS and it's dead on accurate.