Speedometer calibration

[Daredpollo]

I had a chance to check my speed against my hand-held GPS and lo and behold the indicated speed on the speedometer was spot on with the GPS. This after I had just removed my snow tires (32.1 inch) back to the factory tires, which I think are 31 inches. Nice feature, Dookie, and thank you for bringing this to our attention.

By the way, I only had travelled 290 miles since my tire swap. Didn't need 1000 miles!

Best regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 17 July 2018. Now at: 031517 miles.

So, I just had my 35s put on over the weekend and I’ve driven about 70 miles. I downloaded the Waze app too to verify the gps speed and it looks on point. The speeds are the same. I guess they do adjust themselves.


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[Ellisstrong]

So, I just had my 35s put on over the weekend and I’ve driven about 70 miles. I downloaded the Waze app too to verify the gps speed and it looks on point. The speeds are the same. I guess they do adjust themselves.


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Welcome to the club! Lol. I know mine did for sure

 

[Daredpollo]

Yeah. It’s pretty cool to know they do that. I was about to pull the trigger on the calibration tool from rough country.


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[RAM Patriot]

I'm so glad that I found this thread before I dropped $250 Speedometer Calibrators.

RAM it would be nice if you trained your techs and service advisors about this new feature.

 

[greels1]

While i'm not arguing that it is working for some trucks, clearly evident by previous posts. I don't think it works for all trucks.

My speedometer is still off 2-3 mph after moving up to 33 inch tires. It's been about 5,000 miles since I switched tires and its just as far off now as it was then.

 

[Dflood]

Mine was right on when compared to waze, but when i passed the signs that post your speed i was always 2-3 MPH off. Used the rough country calibrator and now I'm dead on with waze and the speed signs. If you use the calibrator you also should measure and use your actual tire size for me I run 35/12.50 and measured it's actually 33.5 on the truck.

 

[jwnelson3]

2019 bh my digital speedometer is about one mile off from my analog. Anyone have this problen?

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[Sspearsau]

I am hoping I am one of the "lucky" ones that does not have to manually recalibrate their speedometer when changing tire size. My truck has navigation, so I am hoping that is the key.

For those that had it automatically recalibrate, how long did it take? I do not often drive my truck long distances, especially with COVID-19 in the air, but I am happy to get on the interstate and ride it out if that is what it takes. I have taken about 5 short trips (4 miles or less, all under 40 MPH). Any thoughts on this?

Thank you!

 

[Ellisstrong]

I am hoping I am one of the "lucky" ones that does not have to manually recalibrate their speedometer when changing tire size. My truck has navigation, so I am hoping that is the key.

For those that had it automatically recalibrate, how long did it take? I do not often drive my truck long distances, especially with COVID-19 in the air, but I am happy to get on the interstate and ride it out if that is what it takes. I have taken about 5 short trips (4 miles or less, all under 40 MPH). Any thoughts on this?

Thank you!

Mine didnt take long at all honestly. Maybe 15-20 minutes of interstate driving. And that’s when I noticed it was reading the same on my speedometer as the waze app.

 

[Dookie]

Same here. Maybe 15 min drive time. I haven’t been able to check it against a radar yet, but Waze App and speedometer are what and what.


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[mrbullred]

I just passed 400 miles since the tire swap and mine is still off by 6-7 mph. I have the 12" with navigation. Hopefully it will happen soon.

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[Dookie]

Crazy how some do and some don’t self calibrate. Yesterday I did some upper hwy speeds (80+) on I10 and Waze GPS MPH and Speedometer were exact.


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[Clyde]

I paid my dealership to calibrate my truck immediately after changing tire size, (about 1500 miles/2 months ago).

Just noticed today that it is off by about 4mph while going 70mph. I was following my wife on the freeway, had her set her cruise (stock VW Atlas) and compared.

So not only did mine not auto calibrate... but what ever the dealership claimed to of done was unsuccessful in calibration of my speedo.

I’m in CA, RC will not sell/send their calibration tool to CA.

 

[RAM Patriot]

I paid my dealership to calibrate my truck immediately after changing tire size, (about 1500 miles/2 months ago).

Just noticed today that it is off by about 4mph while going 70mph. I was following my wife on the freeway, had her set her cruise (stock VW Atlas) and compared.

So not only did mine not auto calibrate... but what ever the dealership claimed to of done was unsuccessful in calibration of my speedo.

I’m in CA, RC will not sell/send their calibration tool to CA.

I would be driving back to the stealership for a refund.

I was told after an hour of the tech trying to recalibrate my vehicle. that the service techs no longer have access to reprogram the speedometer.

You would have to pay FCA to change the tire size on your VIN and then the techs could download that from the FCA server to your truck.

I'm glad mine reprogrammed automatically.

 

[Clyde]

I would be driving back to the stealership for a refund.

I was told after an hour of the tech trying to recalibrate my vehicle. that the service techs no longer have access to reprogram the speedometer.

You would have to pay FCA to change the tire size on your VIN and then the techs could download that from the FCA server to your truck.

I'm glad mine reprogrammed automatically.

I’ll definitely be contacting the dealer , I (supposedly) had it recalibrated when I had a different service advisor, the same one I had numerous customer service issues with...

 

[Jeffjad]

I have the 8.4 no nav and mine did not self adjust. I went to 35's and I'm consistently off by 4-5 mph depending on speed. I have not noticed any performance differences other than my gas mileage got worse but to be expected with lift and bigger tires. It really doesn't bother me so I'm not going to mess with it.

 

[TH3JUICEMAN]

I have the 8.4 no nav and mine did not self adjust. I went to 35's and I'm consistently off by 4-5 mph depending on speed. I have not noticed any performance differences other than my gas mileage got worse but to be expected with lift and bigger tires. It really doesn't bother me so I'm not going to mess with it.

I’m in the same boat, if my “miraculously” recalibrates, great, if not, no biggie.

 

[Chrisdp23]

So I went to a slightly larger tire 275/60 20, and as others started to compare the Speedometer and GPS speed to see if i was going to need to recalibrate. They both read the same so I was happy. I then took a 420 mile (one way)trip and as always reset the GPS Trip info so I would get a actual drive time and my trip A so I could see my miles as I traveled. I stared checking speed and GPS and they read the exact same, but as the trip went on I noticed my miles travel started to fluctuate between the 2. Upon arrival my trip odometer said I had traveled 421miles, the Trucks Nav gps trip info said 452 miles. It did the same on my return trip. I would not trust the method of comparing the two speeds becuse something is definitely off on mine, although they read the same. I also started checking against the mile markers and the GPS appeared to be the accurate one.

 

[JimD007]

Interesting thread. I have stock size tires and my speedometer reads the same as my aftermarket GPS (Kenwood, Garmin NAV).

My dealer tried to sell me a GPS locator for $500. They said it would save me on insurance. But they wanted written proof of insurance before I left. So I called SF and got it but I also asked about the GPS they were offering. They said no change. So I declined. But there still seems to be a GPS receiver on the truck. I think this is a dealership thing but I am curious. A GPS input to the vehicle would not have to be for navigation.

My other story is probably even less interesting but maybe someone will like. I also drive a BMW convertible. BMW deliberately makes their vehicles read 2-3 mph faster than they are going. They bury the software so deep that nobody has found it. I have an out of date version of the dealer software and even with it, we cannot find it. There is a digital speedometer option for a display that also will show mpg and other things. I removed the "correction" from that and it agrees with my GPS in that vehicle. So the car knows how fast it is going, BMW just decided to fib. At least Ram is not purposely misleading us. I pay no attention to the speedometer in my convertible. I use the digital indication or the GPS.

 

[WXman]

Yes, Rams and Jeeps (DT, JT, JL, etc) will self-calibrate to new tires, but only if you have NAV so that the vehicle is ingesting GPS data. If you don't have NAV, you'll need to do it manually.

Since I already had a Tazer JL, I reused that on my JT, and now I'm reusing it again on the DT. Wonderful tool that does a lot including activating my LED headlights and foglights.