Tire Diameter Changes.... Has it Affected Your Liberty?

kevjam79 · **Posted:** Wed Oct 21, 2009 10:59 pm

Hey guys and gals,

I was wondering if anyone has seen changes in the following systems due to increasing the overall diameter of your tires.

ABS

ESC

ASTC

ERM

These systems should be affected by the change in diameter but I am trying to determine to what degree does it affect the driveability.

I really would like to lift and go to a 245/75 R-16. But I don't want these systems to overcompensate and create driving issues, specifically for my wife.

Thanks for any info you can provide.

Kev

Jeepin_it_real · **Posted:** Wed Oct 21, 2009 11:23 pm

if you going to do all that work, might as well get some new pads and slotted( maybe even drilled ) rotors..and call it a day, obviously its going to slow down braking a bit but form what i understand its nothing tragic... you have other options such as stainless steel brake lines, which should take the spongy-ness out of the pedal... a bunch of options here. i say go for the lift and the tires!

kevjam79 · **Posted:** Wed Oct 21, 2009 11:35 pm

I am not worried about brake wear and tear. I am concerned about the Bosch(I think...) stability programming/controller not being able to compensate for the change in tire speed due to the increase in diameter. I had asked the question in an earlier thread if the ECM was programmable to match your tire size. It seems as though no one has a definitive answer. So my next question was an experience based question. Any advice is greatly appreciated.

Kev

bettsyboy · **Posted:** Wed Oct 21, 2009 11:38 pm

as long as all 4 are the same size you will be fine, no codes, no problems all functions operate as normal.

you can also get your tire size changed by the dealer in your computer... all the KA, KJ, and KK sizes are listed and the largest overall is the 20" size from the Nitro.

My 245/70R17 worked out to be about 2.9% too large instead of about 6.5 or 7%

Boblemoche · **Posted:** Wed Oct 21, 2009 11:40 pm

with my 285/75 16 everything works fine and the drivability is almost as good as stock but the only thing is when I do sharp turn at relatively low speed the esp tend to kick in for no reason but it only makes noise and still drive fine. I got annoyed by this and disabled the esp

kevjam79 · **Posted:** Wed Oct 21, 2009 11:45 pm

bettsyboy wrote:

as long as all 4 are the same size you will be fine, no codes, no problems all functions operate as normal.

you can also get your tire size changed by the dealer in your computer... all the KA, KJ, and KK sizes are listed and the largest overall is the 20" size from the Nitro.

My 245/70R17 worked out to be about 2.9% too large instead of about 6.5 or 7%

Do you have a list of those sizes? Or can point me to them?

bettsyboy · **Posted:** Thu Oct 22, 2009 12:02 am

i dont have the list with me its in the starscan... if you search for the tire sizes available for all of the Nitro's and Libertys for all years, you will have the list.

Scar0 · **Posted:** Thu Oct 22, 2009 1:38 am

Check this thread post 5-6 for the stock tire sizes programmable.
http://www.lostjeeps.com/forum/phpBB3/vie ... hp?t=46790

hrogi · **Posted:** Thu Oct 22, 2009 2:48 pm

Most of these system will do better after the ECU change.

BUT
if you di dnot change the ECU you will be fine as well.
The system using input from source other than tire it self.

So the size can change and it will still work.

Below is a dumbed down how it works guide.
This is not techny or right, but it close enough to give yu an over all understanding.

for ABS. once a wheel locks up it locks. 14 inch or 48 inches a lock wheel is a locked wheel. Then it will release pressure and let it move till it locks again..

But in any case, get the ECU adjusted and things will work the way you want it to..... As this is for the wife, you can sleep better at night knowing the KK is a peak tuning this way.

wolverine · **Posted:** Mon Oct 26, 2009 12:23 pm

Forgive me if that has already been answered, but I searched and couldn't find an answer regarding a KK.

Is there an "Other" setting on the dealer programming tool to allow putting in a custom number of revs per mile instead of going with the list of stock wheels/tires?

I really don't care about the speedometer, but if that is possible, does it also change the shift points for an auto?

thanks

Scar0 · **Posted:** Mon Oct 26, 2009 7:32 pm

wolverine wrote:

Forgive me if that has already been answered, but I searched and couldn't find an answer regarding a KK.

Is there an "Other" setting on the dealer programming tool to allow putting in a custom number of revs per mile instead of going with the list of stock wheels/tires?

I really don't care about the speedometer, but if that is possible, does it also change the shift points for an auto?

thanks

Nope. Sorry to say we are stuck with what is in the system.
There are some aftermarket systems that can compensate for a larger tire and speedo differences. But there is no way to program the sizes within the existing system, other than what is already there.

Diggerfreek · **Posted:** Mon Oct 26, 2009 7:40 pm

Scar0 wrote:

wolverine wrote:

Forgive me if that has already been answered, but I searched and couldn't find an answer regarding a KK.

Is there an "Other" setting on the dealer programming tool to allow putting in a custom number of revs per mile instead of going with the list of stock wheels/tires?

I really don't care about the speedometer, but if that is possible, does it also change the shift points for an auto?

thanks

Nope. Sorry to say we are stuck with what is in the system.
There are some aftermarket systems that can compensate for a larger tire and speedo differences. But there is no way to program the sizes within the existing system, other than what is already there.

Are there any "black boxes" made for the KA?

Scar0 · **Posted:** Mon Oct 26, 2009 7:47 pm

Just the ones that plug in under the dash. I don't remember the brand, but they are supposed to compensate for tire size change/speedo differences. I have seen them mentioned (I think it was here) but have not tried one.
Like this...
http://www.autoanything.com/performance ... 7A0A0.aspx

bettsyboy · **Posted:** Tue Oct 27, 2009 3:03 pm

Scar0 wrote:

Nope. Sorry to say we are stuck with what is in the system.

confirmed

there are a bunch of sizes, but all of them are factory options on some year, make, model of KA, KJ, or KK

MtnLuvr · **Posted:** Sat Nov 28, 2009 7:30 pm

kevjam79 wrote:

Hey guys and gals,

I was wondering if anyone has seen changes in the following systems due to increasing the overall diameter of your tires.

ABS

ESC

ASTC

ERM

These systems should be affected by the change in diameter but I am trying to determine to what degree does it affect the driveability.

I really would like to lift and go to a 245/75 R-16. But I don't want these systems to overcompensate and create driving issues, specifically for my wife.

Thanks for any info you can provide.

Kev

With my 245/75R16 tire size on since last spring and about 6,000 miles later, I've observed no issues with any of the systems you're concerned about.

madrock08KK_AZ · **Posted:** Mon Dec 07, 2009 1:05 pm

It's been approximately 3,000 miles since I have had my 245x75x16 MT on, and I have not had any issues. If I make a sharp turn on a highway overpass, the ESP does kick on.

JEEPIN36COKK · **Posted:** Tue Dec 08, 2009 8:49 pm

Since adding 245 75 R 16 Goodyear MTR with Kevlar no issues, just little loss in MPG, added 91 octane, seems to be fine, no lift yet BTW.

RPM007 · **Posted:** Tue Dec 08, 2009 10:17 pm

Scar0 wrote:

Nope. Sorry to say we are stuck with what is in the system.
There are some aftermarket systems that can compensate for a larger tire and speedo differences. But there is no way to program the sizes within the existing system, other than what is already there.

Will it ever be possible to alter the software to recognize a bigger tire? Are other Jeep models' programming limited to stock tire sizes as well? I want to lift, but I do hate to lose EVIC, odometer and speedometer functionality.

DirtyKK · **Posted:** Wed Dec 09, 2009 12:15 am

i get the norm of terrible mpg and also my esc kicks in on occasion

Tire Diameter Changes.... Has it Affected Your Liberty?

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