Speedo recalibration after wheel upgrade

[Sawboss3]

I'm driving a 2019 2500 that came with the 17" steel wheels, and I have upgraded to 18" aftermarket wheels with some larger (but still reasonable) AT tires. My overall diameter went up from 30.5 to 33 inches, which messed up the speedometer reading. In an effort not to be a lead foot (and the light wallet that comes with) I thought I'd figure out what to do with the speedo. Not wanting to hassle with going back to the dealership, I looked into Rough Country, who sells a calibration tool for Ram trucks. I was skeptical, since the RC web site fitment checker told me this tool was not compatible with my truck. I verified with their customer service chat, and was told it was compatible. I was pleasantly surprised that it worked exactly as it was supposed to, and my speedo is accurate once again. It was a little tricky to plug in - I had to fish my big meat hooks up under the dash and land a small plug into a small hole, but once I got that handled, it was quick & easy. Anyway, I didn't see any threads here talking about the RC tool, so I thought I'd share my positive experience. It is Rough Country part# 90019 - Ram Speedometer Calibrator (18-20 Ram 1500/2500/3500) This one is for the gas motors. Looks like they sell a different one for diesels.

 

[Cely1932]

Does it need to stay plugged in all the time? What are the options available to recalibrate?

 

[EODMatt]

Thanks For sharing this!

 

[User_1648]

This is good news! I had a Hypertech in my last truck that I had to disassemble the dash to install it. Getting ready to put 37's on my truck, so this will be just what I'm looking for. Thanks @Sawboss3!

 

[Sawboss3]

Does it need to stay plugged in all the time? What are the options available to recalibrate?

No, it only needs to be plugged in while you are calibrating. When you are done, you can unplug. You need to enter the diameter of your tire when it is running the calibration. It goes in quarter inch increments. I don't remember how low it starts, maybe 26 inches, and might go up to 44.

 

[Sawboss3]

This is good news! I had a Hypertech in my last truck that I had to disassemble the dash to install it. Getting ready to put 37's on my truck, so this will be just what I'm looking for. Thanks @Sawboss3!

Though it wasn't mentioned in the instructions, I took off the panel below the light switches (where the autopark release is) and it helped me see where I was going with the plug. Still was a little tricky to maneuver through all of the wiring looms tucked away up in there. Someone with smaller hands would likely have an easier time plugging in.

 

[MikeXM]

Though it wasn't mentioned in the instructions, I took off the panel below the light switches (where the autopark release is) and it helped me see where I was going with the plug. Still was a little tricky to maneuver through all of the wiring looms tucked away up in there. Someone with smaller hands would likely have an easier time plugging in.

Doesn't it plug directly to the ODBII port?

 

[Sawboss3]

Doesn't it plug directly to the ODBII port?

No, that's what I thought it would be , but it doesnt use the obdii port. It is a different spot up under the left side of the dash. A little harder to get to, but not impossible. Took me a few minutes of maneuvering, but it went in.