walter the jeep

hello,

so i got 4:10 ratio on my back axle and put on 35 inch tires, my gearing if for stock tire size and ratios. how do i change the gears to work with the new ratio?

resharp001

Bit confused by the international grammar. Your 2012 wrangler has 4.10 gears. You mention only the rear. You have 4.10 gears both front and rear correct? You've put on 35" tires, and you're asking how to adjust things for the change in tire size? That is what I think you're asking. If that is the case, you just need a programmer to tell the computer what your actual tires size is. You don't HAVE to program the tire size, but your speedometer and calculated fuel economy will be off a bit if you don't. Moving up to a 35" tire, your speedo will be off by about 5mph (~8kph) up at highway speeds if you don't adjust.

nthinuf

Pay a dealership to reprogram tire size. (not sure about max height, I've seen different responses.)
Buy a Programmer: AEV ProCal , Superchips FlashCal, etc
Buy a Tuner : Superchips FlashPaq or Traildash, Diablosport, BullyDog, etc etc

Note that programmers/tuners lock to a vehicle VIN number. So if you buy a used one, MAKE SURE that the previous owner went back to stock and unlocked it.