Transmission Tuning Due to Tire Size Increase

[Whittsram]

Has anyone tuned their Transmissiom's Computer to adjust for an increase in tire size? Please reply with a Yes or No.

I'm now running a 295/64R/18. This tire is exactly 1.67" larger in diameter than factory.

Ram/Chrysler is now claiming that my 3 transmission failures in the last 7 months is due to this tire being installed. Thoughts? I'm going against FCM with an arbitrator tomorrow. Thanks

 

[22hemi13]

NO 35”s for almost a year and now 37”s. Still not calibrated but I need to. Tranny is fine

 

[U&A]

Yes

AEV ProCal.


It definitely needs to be done. You truck measures output shaft speed in relation to tire speed. If they are to far off from each other it confuses the trans and makes the torque converter and clutches work harder and everything else along with it.

Sent while firmly grasping my redline lubed RAM [emoji231]

 

[22hemi13]

Yes

AEV ProCal.


It definitely needs to be done. You truck measures output shaft speed in relation to tire speed. If they are to far off from each other it confuses the trans and makes the torque converter and clutches work harder and everything else along with it.

Sent while firmly grasping my redline lubed RAM [emoji231]

Very true. One thing I do and would be helpful if you don’t get it all adjusted. I run mine in tow haul and manually put it in the gear I want to keep shifts down. I WOULD NOT RUN IT IN D.

 

[U&A]

T/H helps hide the problem if you done calibrate it. As does manual shifting.


Seriously.....

It needs to be done.






Sent while firmly grasping my redline lubed RAM [emoji231]

 

[Firetruck41]

There are probably tens of thousands of Rams out there with similar sized tires, that haven't reprogrammed anything. I'm not buying that it is common to do so (reprogram) or that it destroyed 3 of your transmissions

 

[Jimmy07]

Yes

AEV ProCal.


It definitely needs to be done. You truck measures output shaft speed in relation to tire speed. If they are to far off from each other it confuses the trans and makes the torque converter and clutches work harder and everything else along with it.

Sent while firmly grasping my redline lubed RAM [emoji231]

I’m gonna poke a small hole in that theory *IN THIS PARTICULAR CASE*. I’m also assuming that the truck in question is the 2014 CTD in his signature, and it has the 68rfe trans. In 2014, the 2500 CTD could be had with 2 different tire diameters- 245/70r17 (~31”), and 275/70r18 (~33”), and 285/60r20 (~33”). The 69rfe has only one factory tune/program file, so it is exactly the same between the trucks with ~2” tire size difference. When you change the tire size with the procal or AlfaOBD, what it is actually doing is changing the values in the BCM to correct the speedometer because the vehicle speed is measured only from the wheel speed sensors. This is the equivalent of having the dealer change the sales code in the bcm for the different factory tire sizes. Nothing related to the transmission tuning or the input/output sensors is being changed. Yes, the bigger the difference between the output speed and wheel speed, the more it affects shifting. But... in this case, he went to a 295/65r18. This is the same diameter as the bigger tire diameter that ram offered from the factory. So, even though he never corrected the speed, the trans is still shifting and behaving exactly the same as if the truck had come with factory 275/70r18 tires. Now, if you’re talking 31” to 35”, then you’re getting into shifts and behavior out of manufacturer specs, and they could have a valid argument.

 

[kurek]

The 69rfe has only one factory tune/program file, so it is exactly the same between the trucks with ~2” tire size difference. When you change the tire size with the procal or AlfaOBD, what it is actually doing is changing the values in the BCM to correct the speedometer because the vehicle speed is measured only from the wheel speed sensors.

Does the transmission controller sample its vehicle speed data from the wheel sensors directly, separately from the speedometer?

 

[dhay13]

Daughter put 35's on her Wrangler with 4.88's and bought a Superchips that only changes speedometer settings and has no tuning function. Think it was a little over $200. Not sure if they have something like that for your truck. You could also customize your shift tables too but we never messed with that.

 

[Ribtipram]

If a little size in tires took out 3 trans in 7 months these are the biggest pile of crap trucks ever made. Don't look at your oil funny or your cam will fall off too. F'n joke. Should you reprogram maybe. Is this the reason your going through a trans every 2 months not an f'n chance.

 

[U&A]

Ok,

Ill voice my opinion one last time. I know the Pro Cal doesn’t tune your trans. I did not mean to come across as if i said that. It calibrates the speedometer so the truck reads the speed it is actually going

Going a different speed than what the truck actually thinks you are going WILL affect shifting and trans performance.

Bottom line.


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[Whittsram]

Thanks for the reply's everyone. My old tire size was 275/70/R18. New tire is 285/75/R18

 

[Sloverado]

Ran 35s for 16k miles no problem and not tuned

 

[Ribtipram]

Im sticking with 3 down in 7 months. Something is Suspicious. That is not easy to do. What is going wrong with these trans's. Did they ever say. Are they over heating. **** breaking. Bypass valve stuck?

 

[Whittsram]

With the most current failure the technician found that the ID CVI is to low being its at 38. Spec is 44-92. To little of a clearance.

The previous two never gave a detailed reason for the failure. Same P0731 code on all of them though. They would drop the pan, indicate failing internals, and swapped the trans.

 

[autokraftgt]

NO
I ran 35's for 98,000 miles on my last Ram....let's just cut the crap...Ram doesn't want to replace your trans cause it costs them money and you having a larger than factory tire gives them leverage in their argument. Now if you went to 40 inch tires then I could see their argument...but you increased the diameter less than 2 inches and that's the problem??
Unreal

 

[46RamMan]

I would like to know what component (s) failed in all three instances.. I sounds fishy to me. The differences in the tire sizes (less than 2") could not possibly cause three failures in such a short time frame.. but then I've only worked on every type of transmission (auto & standard) know to man over the years (50).. so what do I know....

 

[Thundr]

There are probably tens of thousands of Rams out there with similar sized tires, that haven't reprogrammed anything. I'm not buying that it is common to do so (reprogram) or that it destroyed 3 of your transmissions

 

[Thundr]

I have an 05 Ram with a 6" suspension lift as well as a 3" body running 38's and am not having any issues with my transmission. The only thing I see is my speedometer is off by 6mph. If it shows 60 I'm actually going 66

 

[Grant Balint]

Don't look at your oil funny or your cam will fall off too.

hahahahahah that is some funny stuff