Speedo recalibration details?

Coyotefred · **Joined:** Thu Dec 29, 2005 4:50 pm **Posts:** 36

'Anyone here had their speedo recalibration done recently who could share the details? I ask this because no one around my rural seems to have a clue (or in some cases a willingness) to do this. My local Jeep dealer said they can't (won't) do this because "there would be no reason to do this since there is only one tire size specified for your vehicle." Another local shop/dealer says they have the computer to do this, but "can't be sure" whether this would work on my Liberty.

Surely this can't be rocket science? I switched from 235 70 16s to 245 75s and I have figures for the change in RPMs. Can't the computer be manually programmed to account for this even if there is no "preprogrammed setting" for Liberty?

If any of you have gone through a recalibration and wouldn't mind sharing some details I'd appreciate it. At least that way I can go into this with a little more insight on what I might tell folks claiming this can't be done, etc.

Thanks!

KJ04 · **Posted:** Sun Feb 05, 2006 12:27 pm

My dealer said they only had two sizes to choose from.
Called another dealer, and they did it set to Revolutions per Mile and didn't even charge me. Took all of 3 mins. to change it.
Some people have reported charges of $40.00 to perform the service.

Skyjump136 · **Joined:** Tue Jul 05, 2005 6:50 pm **Posts:** 1633

Quote:

Can't the computer be manually programmed to account for this even if there is no "preprogrammed setting" for Liberty?

Yes. The dealer just inputs a revolutions per mile figure. My dealer wanted to charge me the standard $90 "diagnostics" charge but I talked them down to FREE.

It really isn't that hard to do, but most dealers just don't want to take the time to figure it out.

KJ Willy · **Posted:** Sun Feb 05, 2006 2:00 pm

My question is has any figured out how off the speedo actually is?(like 1 or 2 MPH)

I also went to tire size 245/16, the one place to go and see how fast you are going was taken down the day before I got my tires put on. I don't think that I will actually do this but would like to know the different in speed.

Jeepjeepster · **Posted:** Sun Feb 05, 2006 2:02 pm

great site, tells you everything.

http://www.1010tires.com/TireSizeCalculator.asp

Enter your old tire size then compare it to others, it tells you the mph difference.

m0th · **Posted:** Sun Feb 05, 2006 7:09 pm

I just printed the specs off of tirerack.com, took it to the dealer and they did it no probs. I think they charged me for 15 minutes labour, but they also adjusted the headlights as the lift had the front pointing up more.

lilmatty · **Posted:** Mon Feb 06, 2006 11:34 am

KJ Willy wrote:

My question is has any figured out how off the speedo actually is?(like 1 or 2 MPH)

I also went to tire size 245/16, the one place to go and see how fast you are going was taken down the day before I got my tires put on. I don't think that I will actually do this but would like to know the different in speed.

Mine is calibrated for 235s and I've put on 245s. Speed now reads 5% low as measured against both Radar traps and GPS. So if my speedo reads 72ish then I'm really doing 75ish, for instance.

LostRenegade · **Posted:** Mon Feb 06, 2006 10:44 pm

Yes it can be done. The dealer has to hook up their diagnostic tool and set the wheel rotation. I had several dealers tell me that either it could not be done or it would cost me a full hours labor. Keep trying is all that I can say. I found one in Livonia, MI that did it and only charged me a 1/4 hour of labor.

My Renegade came with 235/70/r16 and I put on 245/75-R16 BFG ATs. Before the recal I was about 5% off. Now I am pretty much right on. I think at most I am 1/2 MPH off at 70 MPH. Not bad...

AZ_Overdrive · **Posted:** Tue Feb 07, 2006 9:38 am

I tried to get this done on my 05 Renegade when I went to 245/75's with no luck.

Here is what I found...
Before 05 you could input the rotations per mile and be done with it. On the 05 they changed the PCU (or whatever the processor is called) so that all you can do is choose from a preset tire size. My assumption is that stock sport, renegade and limited sizes are all there is in there. So, that = out of luck.

I took it to 3 dealerships. Apparently, the 05 appears to be able to take the RPM numbers but the computer won't hold the changes. Had dealers calling DC directly to confirm.

Jesus Levy · **Posted:** Sun Mar 19, 2006 1:21 am

Any luck yet setting the computer to new tire size on your 2005 Libby? I am just about to try.

PitViper · **Posted:** Sun Mar 19, 2006 12:18 pm

I need to get mine changed now also and I have a 05

AZ_Overdrive · **Posted:** Mon Mar 20, 2006 10:36 am

No new updates. Still holds true that 05's (and newer?) cannot be set with RPM like previous years.

lilmatty · **Posted:** Mon Mar 20, 2006 12:10 pm

Just figure it in your head. It's 5% low if you had on 235s and put on 245s.

So if you are doing 72mph it's really 75 for instance. That also means at low speed it's almost nominal. Beats the heck out of trying to find someone to calibrate.

This, all verified with a GPS.

Se7enLC · **Posted:** Mon Mar 20, 2006 12:21 pm

lilmatty wrote:

Just figure it in your head. It's 5% low if you had on 235s and put on 245s.

So if you are doing 72mph it's really 75 for instance. That also means at low speed it's almost nominal. Beats the heck out of trying to find someone to calibrate.

This, all verified with a GPS.

So that would make the EVIC gas mileage calculations, odometer, trip meter, all useless. Also, you folks with automatic transmissions will notice shifting in different places.

I'd really like to get it recalibrated if possible when I get larger tires.

Anybody try one of these products?

Digital Speedo Corrector
http://www.eurekaboy.com/f250/truspeed.htm

EDIT: Actually, it looks like somebody was able to get the dealer to adjust their speedometer (in an 05):
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=4408&highlight=speedometer+recalibration
And somewhere else I read that since there are only certain preset tire sizes (and you can't add new ones), you have to actually edit one of the existing sizes to have the right number of RPMs and select that one. Seems like it should work, but I'm not going to run out and buy a programmer to test it.

cowpie · **Joined:** Mon Jul 25, 2005 9:00 am **Posts:** 26

Most tire manufacturers websites have the rotations per mile on the spec sheets for any tire.

My 235s that were on when I bought my jeep were 699 rotations per mile.

The 265/75/16 Nitto terragrapplers that I installed are 669 r/m. Thats less than a 4.5% change.

Consider that most factory spedometers read about 5% higher than actual speed, my 265 tires are dead on at 25, 45, and 65 mph by gps. No recalibration needed.

Skipperb · **Posted:** Tue Mar 21, 2006 10:00 am

Mine came with 235/70 and mow with 265/75 when Im doing 62 it is relay 65. A friend had his radar calibrated and we checked it while he was on duty. I did four passes and it was off about three miles all the time.Are all 265 tires 32 or does it vary with tire manufacturer

Se7enLC · **Posted:** Tue Mar 21, 2006 11:36 am

Skipperb wrote:

Mine came with 235/70 and mow with 265/75 when Im doing 62 it is relay 65. A friend had his radar calibrated and we checked it while he was on duty. I did four passes and it was off about three miles all the time.Are all 265 tires 32 or does it vary with tire manufacturer

265 is the width of the tire (in mm), not the height, so a 265 tire can be any height, specified by the sidewall percentage (the 75).

All 265/75R16 tires *should* be the same, but it does vary by tread and manufacturer.

Littlehorn · **Posted:** Sat Apr 01, 2006 8:47 pm

Can this lack of change affect the '05's timing or combustion in any way? I have noticed what appears to be "wet fouling" or greasy soot residue in and around the edge of the tailpipe end. There is 6200 miles on my '05 Renegade. I do take daily short 8 miles trips to work and home.

onespeeder · **Posted:** Mon Apr 03, 2006 3:25 pm

Is the device to recalibrate the speedo a dealer specific one. I think DRB or DBR? A guy here at Jeep Masters tells me that if it can be done with an OCB(?) or Snap-On scanner he can do it. Anyone have a clue about that?

My stealership wants to charge me $95 and I have to leave the truck. :evil:

wolf4wd · **Posted:** Mon Mar 26, 2007 8:38 pm

I just read through this message group after returning from the Dealership with no help - not to say they didn't try, however.

I have a 2005 Sport and just upgraded to 245/75-16 Richard Cepek, available through Les Schwab in the area, Mud tires. I called the dealership and they said yes to a Speedo Re-Cal. They spend about an hour and ended up with the same problem that others of you posted - that they could only put in the "Stock" tire sizes. any other number of revolutions shut my speedo down competely; it didn't register anything at all.

The tech was willing, but stumped by the problem. I DO NOT have anti-lock brakes; he thought that maybe that was the issue as they control the speedo on those vehicles. So he was wondering if the BCM could be flashed to accept the new number of revs per mile. Do any of you know about this OR are you aware of other sources to recalibrate the speedo on a 2005 w/ Anti-Lock or what is it the EV module?

The dealership is a very good one in the area so I am not bashing them, I am just a little frustrated, but they are trying to work with me, so any suggestions would be very welcome!

Thanks everyone - this site is so great!

Speedo recalibration details?

Who is online