2020 Ram 1500 Speedometer calibration and Park Sense issue, any ideas or suggestions?

[jayhawk]

Hello everyone!
I need you guys’ help on my 2020 Ram 1500 Laramie.

I recently changed my stock tires 275/55R20 to 35x12.5R20. As a result my speedometer was off.

I took it to the dealership and showed them the Star Online Publication Case S2008000110 for changing tire size. They tried doing it and when they tried 35 all the sensors were turned off, so they set it to 34 instead.

However, now my ParkSense is dead both front and back. It has the lights on the switches but on the dash it is displaying unavailable.

I have looked most of the posts on the forum and I might try these steps, let me know what everyone thinks.

1. Take it to the dealership again and try 33.5, if that fails I’ll just ask them to revert it back to stock.
2. Use alphaobd to do it on my own.

Anyone who had the same experiences and managed to solve this issue, please let me know, I don't want to lose my ParkSense functions.

Thanks in advance!

 

[frisby5]

Hello everyone!
I need you guys’ help on my 2020 Ram 1500 Laramie.

I recently changed my stock tires 275/55R20 to 35x12.5R20. As a result my speedometer was off.

I took it to the dealership and showed them the Star Online Publication Case S2008000110 for changing tire size. They tried doing it and when they tried 35 all the sensors were turned off, so they set it to 34 instead.

However, now my ParkSense is dead both front and back. It has the lights on the switches but on the dash it is displaying unavailable.

I have looked most of the posts on the forum and I might try these steps, let me know what everyone thinks.

1. Take it to the dealership again and try 33.5, if that fails I’ll just ask them to revert it back to stock.
2. Use alphaobd to do it on my own.

Anyone who had the same experiences and managed to solve this issue, please let me know, I don't want to lose my ParkSense functions.

Thanks in advance!

Im taking mine to the dealer on Friday to change mine . I went to a 275 65 20 , i tried Alphaobd first and was able to change in mm but it was still.off some.So when i tried a second time i couldnt initialize abs and had dashlight errors. I had to take to dealer to clear. Will se if they have any issues.

 

[jayhawk]

Im taking mine to the dealer on Friday to change mine . I went to a 275 65 20 , i tried Alphaobd first and was able to change in mm but it was still.off some.So when i tried a second time i couldnt initialize abs and had dashlight errors. I had to take to dealer to clear. Will se if they have any issues.

What value in mm did you enter?

 

[frisby5]

What value in mm did you enter?

I put in 2718 mm

 

[jayhawk]

I put in 2718 mm

I saw a post from the forum that anything over 2710mm might have an issue

 

[HSKR R/T]

When I switched to my 275/65/20, I used my Pulsar to cha ge the size and ended up with a 265/60/20 in order for speedo to be correct. Now that I ha e switched to 35x12.50x20 I used my TazerDT to change size. With the Pulsar setting it was showing 34.15", I changed it to 34.7 with the TazerDT and now GPS indicated speed is 71mph, when speedo shows 70.

Zero issues with park Sense

 

[frisby5]

I went down in size to 2680 ,it put the calibration in but it wouldnt intialize abs so i was getting a esc error the start procedure was grayed out on the alphaobd

 

[cskindt]

I went down in size to 2680 ,it put the calibration in but it wouldnt intialize abs so i was getting a esc error the start procedure was grayed out on the alphaobd

Did you recalibrate abs after you changed tire size?
I had to on my '22.

 

[frisby5]

Did you recalibrate abs after you changed tire size?
I had to on my '22.

It wouldnt let me on AlphaObd the ABS screen for the procedure was greyed out ,i found some other people had the same issue ,they never said what they did to correct it on the posts i found

 

[jayhawk]

UPDATE!
I managed to get my parksense back with Alphaobd. The only way to make the parksense work for my 2020 Ram 1500 Laramie was to set the diameter to 2557mm, anything over that will turn off the Parksense. I guess I will stick to this size until I can find a better solution.

 

[frisby5]

When I switched to my 275/65/20, I used my Pulsar to cha ge the size and ended up with a 265/60/20 in order for speedo to be correct. Now that I ha e switched to 35x12.50x20 I used my TazerDT to change size. With the Pulsar setting it was showing 34.15", I changed it to 34.7 with the TazerDT and now GPS indicated speed is 71mph, when speedo shows 70.

Zero issues with park Sense

Which is better Pulsar or Tazerdt? I have Bafx

 

[HSKR R/T]

Which is better Pulsar or Tazerdt? I have Bafx

Tazer was much easier.

 

[jayhawk]

UPDATE

Thanks to Njh3409

Post in thread 'Alfaobd tire size change instructions'
Alfaobd tire size change instructions

I tried replacing park assist module to 68464879AG and now I can set the tiresize over 2557mm without disabling the parksense!

 

[VectorZ]

I'm on iOS and used JScan to change my tire size, didn't go that big though.