Tires and speed

NJ KJ · **Posted:** Fri Jul 21, 2006 1:03 pm

I finally got new tires for my lifted liberty and want my speedo to work correctly and was wondering if any one had managed to fix theirs??? is it similar to the old precomputer vehickles where u change the gear in the tranny??? or is it all computer where u re program something btw i got BFG 245/75/16 AT/KO's verses the stockers 225/75/16 good years..... any help would be appreciated

2006KJSPORT4x4 · **Posted:** Fri Jul 21, 2006 1:24 pm

I think the dealer can recalibrate it for you if you tell them your tire size and whatnot....it is a reprogram thing from what I was told by my local tireshop...i just need to find time to take it in and have it calibrated myself...

my .02

Se7enLC · **Posted:** Fri Jul 21, 2006 2:21 pm

RockyMtEditionKJ wrote:

I think the dealer can recalibrate it for you if you tell them your tire size and whatnot....it is a reprogram thing from what I was told by my local tireshop...i just need to find time to take it in and have it calibrated myself...

my .02

If you do it you'll be the first 2005+ to have it done. I have not yet heard of anyone doing it sucessfully on anything but a pre-2005 evic (they changed a lot of stuff in 2005, including from what I can tell, a limit that prevents them from entering anything but the two accepted tire sizes)

FL RENNY · **Joined:** Mon Nov 07, 2005 4:30 pm **Posts:** 458

The dealer can do it for you, but they wanted to charge me $90........I learned to live with it lol.

Mutt · **Posted:** Fri Jul 21, 2006 3:26 pm

Funny thing is that stock your speedometer isn't accurate. Most new cars have a speedometer error up to as much as 10%. After installing my lift and tires, I searched out one of those construction zone radar signs and found that my speedo was dead on. Of course I'm taking into account my assumption that the sign was calibrated.........

Loopkey · **Posted:** Fri Jul 21, 2006 3:35 pm

I just had mine done on my 2002 with BFG AT/KO 245/75/16's and we ended up with 712 or 722 rev's per mile can't remember now. If the tech can find it in the ODB II menus 712 will be a good place to start.

kj@best · **Posted:** Fri Jul 21, 2006 4:15 pm

I was told by my stealership, that alog with recalibration of computer........a gear must also be replaced in either the transmssion or differential I forget

DaveKJ02 · **Posted:** Fri Jul 21, 2006 4:17 pm

682 rev/mile

tarkus · **Posted:** Fri Jul 21, 2006 5:13 pm

kj@best wrote:

I was told by my stealership, that alog with recalibration of computer........a gear must also be replaced in either the transmssion or differential I forget

Time to find a new stealership.

Se7enLC · **Posted:** Fri Jul 21, 2006 7:26 pm

tarkus wrote:

kj@best wrote:

I was told by my stealership, that alog with recalibration of computer........a gear must also be replaced in either the transmssion or differential I forget

Time to find a new stealership.

Yeah, seriously. The KJ has no speedometer gears, it's all done in the computer. I'd like to see a dealership charge for a gear. While there at it, I'll have them top of my blinker fluid.

Construction zone speedometer signs are NOT accurate at ALL. Borrow somebody's GPS and see what that says for a speed, and try it at highway speed (since the error will be a percentage, it's easier to notice it when you are going faster). My speedometer is very accurate (within 1mph) at all speeds according to my GPS, but I still have stock tires.

ice_man_7c · **Joined:** Thu Apr 27, 2006 10:25 pm **Posts:** 72

i am just gunna take a drive with my GPS that i use while snowmobiling, and see how much it's off.... and compensate from there

NJ KJ · **Posted:** Sat Jul 22, 2006 9:34 am

So I just got off the phone with the dealership and have come to the conclusion that they have no clue what is gooing on..... they said that all it was was a reprogram for the new tire size.... ok thats what i guessed from everyones feedback... no prob there... BUT they said its a 50/50 shot if it will work or not some cars it works on and some it dosent... What the hell does that mean?? and it runs 90$... so how can it work on some and not others arnt all the computers on all the crd's are the same??? hence the principal behind mass production??

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

It means you need to use a different dealership. The majority don't know how to program the computers. I had B&G Chrysler program mine. Much nicer than any dealership can program it.

DarbyWalters · **Posted:** Sat Jul 22, 2006 1:27 pm

Your speedo probably was reading about 3.5% slow...speedo says 70 on stock tires and you are traveling 67.5...

Both my KJ's have had the same error...funny thought the odometer reads less than the miles traveled by my GPS...about 2% off

Tires and speed

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