how do I calibrate pinion for new tires on 2006 CTD?

[Brock]

Well, I put the new Nitto Terra Grapplers (295x70x17)on over a week ago and have been in the mud. . the sand and on highway and love them... . but had not been calibrated.



So went by dealer today to get it done... he said it is a $40 charge... . so I said go ahead. They got into the ECM... ..... and could not do it. It only listed metric size tires on their loader... . and the largest it had was 285x70x17.



While they were in there they asked... "What rear end and differential does this have?"

I asked them why and told them 3. 73 with 11. 5 inch rear end. He said it was loaded as 9. 5 inch rear end and 3. 21 ratio... . if he was looking at it right.



The loader would not let him manually enter a size though... but it was completely different than an 05 load he said. He said they usually go into the ABS section to do changes... . but he found it in the TMS section or something like that. So they set it to 285..... set the rear end to 3. 73 and put a 11. 5 diff in system. Did not charge me and said they are calling tech support to find out why they cant manually enter Revs Per Mile and it only listed metric sizes... no 31s, 33s, or 35s, etc... .



By the way... I searched four different calculators and they all said something different with some usually around 606 revs per mile and others said 625. 5 revs per mile. They measured the tire and said it was 105 inches in circumfrence so that made it around 606 revs..... that is with 65lbs in rear tires.



So here is my question...



Any of you 06 guys had your tire size changed for the pinion gears at your dealerships... and if yes, did you put anything larger than 285s on your truck. If you did and they entered revolutions per mile manually... . do you think you could find out where they did it in the system and what software version they were using? So I can go by and give my shop the skinny? They did not charge me and said until they got it right it was not right.....





Does it sound right that my truck would be set with 3. 21 rear end like that... and what would that have done to my performance if that was in fact how it was set from factory. Would that mean that the miles I show are really like 25-50% higher... ... ... . as well. It seemed to be much more responsive on the throttle..... and the overhead was showing much different mpg.





Any help would be appreciated... .

 

[BRuppel]

If you go to the tire manufacture's website they will tell you the revs per mile on there.

 

[klenger]

I don't think that axle ratio makes any difference. My understanding is that the speed sensor is on the rear axle, not the driveshaft, so axle ratio does not affect calibration. My calculations show 606 revs per mile.

 

[jdaigle]

I've owned an 06 since Nov. and have not found a method for recalculating the speedo. The 06 are quite different from earlier models with regards to speedo corrections... . at this ten seconds I understand it can't be done. If anyone out there who has an 06 and successfully recalibrated their speedo please share with the rest of us.



Thanks,

Jason

 

[Brock]

Yes 606 is the calculation... . but on the software that is loaded it is not allowed to be manually entered and if any tires are used that are not listed... by name brand or size then you cannot select on current 06 software.

Dealership said they thought they could get tech support to fix it for them... so will let you know what happens.



I wonder how the superchip allows changing tire size on their new upload for the 2006? It might become a really good deal if the dealers are prevented from larger tire loads.



What metric sizes equal a 33 inch tire that we could use to confuse it? They put a 285 on it for now... . speedo seems to be about 1. 5 mph slow... . so not too bad... but would rather have it dead on.



Yeah I did not think the axle ratio made a difference on speedo... . it was just something they said was loaded incorrectly in my truck... so I actually had/have two issues.



1. Cant manually load 295 size tires or US Sized 33,35, 37, etc into 06 ECM... .



2. They found my rear end was programmed to run as a 3. 21 with a 9. 5 rear end... . instead of the 3. 73 and 11. 5 inch rear end. What differences would this make in performance, driveability, etc..... in this electronic drivetrain?





If my dealership breaks the code on the tire changes... I will be sure to post.

Thanks for any help... .

 

[blacksheep4x4]

I ran into the same problem when I put my 35" Cooper STTs on my Megacab.

I believe the calibration they put in was the 315 20 R 55 tire size and got it within 1 mph at 75 mph.

 

[Brock]

If you go to the tire manufacture's website they will tell you the revs per mile on there.

Nobody has the revs for the Nitto Terra Grapplers in this size listed... . but it computes to around 606... with a 105 inch circumference

 

[BRuppel]

I'm sure you can call the manufacturer and get them to tell you.

 

[Brock]

we know the revs... . 606..... what I really need is someone to tell me if they have successfully used a dealer to calibrate to anything larger than 285s... and how their dealer did it on their 2006 CTD.



It is within 1. 7 mph now but would like it to at least less than 1mph if possible or deadon would be better.



I might send a note to Superchip to see how their program updates the tire size in their latest release... ..... unless someone knows that already.

 

[ataboy9026]

The overall height of that tire is 33. 19" That would make around 626 rev/mile. Maybe I am wrong. But I noticed the Nitto's are not the same height as the "standard" 295/70/17 tire. I have these same tires and Had mine done and I dont think its even within 3 mph. But the dealer told me they had a 3 mph allowance for error and would have to charge me again to change it, so I just live with it. I asked them what they set it at and they didn't know... . just said they "punched it in" to tire size.

 

[SRubenstein]

I'm not 100% sure this will work but here is what I do know. I talked to my Chrysler dealer and he did confirm that the VSS is the same P/N for '05 and '06 and it actually is the same all the way back to '93. When I had my '01 the Revs Per Mile scale did not go high enough w/ the DRB scan tool. I purchased a Superlift Truspeed sensor calibrator (which is nothing more than a variable resistor, so to say). On an '01 model the speed signal to the ECM comes from the ABS controller. It is the same in '05 ('06 I'm unsure about, don't have the newest wiring diagrams yet). If you look on Superlifts' website they only list it up to the'03 model but the wiring diagrams look very similar between '03 and '05. In '03 it used a wht/org wire from the abs controller (VSS signal) on '05 that same signal is a dk grn/yel at the abs controller connector 1 pin 12. The 2 unknowns are is the processing signal the same? (should be, same VSS p/n used) and is the '05 set up the same way as the '06 (wiring wise). I can fax you diagrams if you need them and should have an '06 diagram by Friday or Monday. I hope this info helps. I really want to see if this will work. Maybe superlift could answer more questions but I doubt it (I've dealt w/ there tech support, nothing impressive)

http://www.superlift.com/accessories/truspeed.asp

 

[sag2]

StarScan does not have the ability to manually input tire size like DRBIII does. Have not heard if they plan to change in the future.

 

[Bob4x4]

I'm not 100% sure this will work but here is what I do know. I talked to my Chrysler dealer and he did confirm that the VSS is the same P/N for '05 and '06 and it actually is the same all the way back to '93. When I had my '01 the Revs Per Mile scale did not go high enough w/ the DRB scan tool. I purchased a Superlift Truspeed sensor calibrator (which is nothing more than a variable resistor, so to say). On an '01 model the speed signal to the ECM comes from the ABS controller. It is the same in '05 ('06 I'm unsure about, don't have the newest wiring diagrams yet). If you look on Superlifts' website they only list it up to the'03 model but the wiring diagrams look very similar between '03 and '05. In '03 it used a wht/org wire from the abs controller (VSS signal) on '05 that same signal is a dk grn/yel at the abs controller connector 1 pin 12. The 2 unknowns are is the processing signal the same? (should be, same VSS p/n used) and is the '05 set up the same way as the '06 (wiring wise). I can fax you diagrams if you need them and should have an '06 diagram by Friday or Monday. I hope this info helps. I really want to see if this will work. Maybe superlift could answer more questions but I doubt it (I've dealt w/ there tech support, nothing impressive)

http://www.superlift.com/accessories/truspeed.asp

The 05 and 06 are night and day different electronics :-laf



Bob

 

[SRubenstein]

They may be, however the concept behind the speed sensor may be the same. I should be getting my quarterly update for Alldata this weekend. I'll look at the new diagrams and see just how differnt that system is. Just the fact that the same VSS is used from at least '93 to '06 tells me that they are still working off the same AC voltage strategy. The Truspeed would just adjust how high the voltage signal is. There's always a way, just kind of hidden right now. Half the fun is figuring out how to do it. :-laf

 

[Brock]

i told them i thought it should be 625. 5 but when he got out the tape measurer and measured circumference of tire he got 105 inches... ..... and that works out to 606 revoluations per mile... so the Nitto must be larger slightly than a standard 295 tire.

 

[Brock]

yeah the guys at shop that do these all the time..... took an hour trying to find it in the 06 ECM (TCM) when it was not under pinion factor under the ABS area... .



They went through everything and no manual entry was visible but thought the last revision of software allowed it...



They are going to see if they can get them to change it or if they can load older version of software to bypass the new setup.



I will let you know what I find out... . but hope someone here breaks the code first so I can show them how to do it... LOL

 

[Bob4x4]

The system useses diferent modules and a diferent language :-laf :-laf

That's why I bought the 05



Bob

 

[JCleary]

Has anyone been successful with changing tire size on the '06 trucks?



I'm about to pull the trigger on a new truck and need some more encouragement...

 

[betterthanstock]

I got 315 on mine 3 years ago (03), and all they knew to do was to input 285. The odometer is off by 5. 8% (makes warranty longer), and the speedo is off by 3 mph at 70. All speedos read 1-2 mph high from the factory (safety thing) so if you have 295, 285 should be almost dead-on for speed (not odometer).