Speedometer calibration

[Aaron Mopar]

I put 5" RC lift with 35" tires on my 3.92 longhorn last week. I noticed the speedometer is off. 3 questions: 1, has anyone used the z automotive tazer DT to adjust speedometer? It says adjust tire size but doesn't say anything about speedometer or shifting points. 2, does larger tires/speedometer calibration have any effect on odometer? And 3rd, anyone live in California? All these say not for sell in California. Thanks

Great looking lift! I haven't used the z automotive tazer DT you mentioned, but I did use the RC calibrator tool. It does the shift points for sure. I noticed a huge improvement after calibration and I only went up 2 inches in tire size. Yes, having larger tires and stock calibration will make your odo read slower. I'm not in California either, so can't help you there. I will say I'm having an issue with the RC calibrator. When I put a cal on my truck with it, my active parksense is disabled. But it works when I remove the calibration and return it to factory tire size. I'm going to have to call RC to solve that one. They may need to send me a new one.

 

[Bradfair1]

I am having the same issue with my RC. It calibrates my speedometer but it disables my parksense. It works fine when I turn it back to stock. Did you ever get a resolution on this? I tried to chat with them and they said they have never seen that issue before. I have a 2020 limited 5.7 with etorque.

 

[thrasherjosh]

I used superchips and haven’t had any issues!


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[Dookie]

Not sure if I'm late to the party or not, but...I was just told by someone I trust at the dealership I purchased my truck from, he has been my "Mopar Parts Guy" for the better part of 15 years, that all DT Rams will self calibrate the odometer through GPS after 1K miles after a tire size change. I asked if he was 100% certain, and he confirmed. We shall see, getting 285/55R22's installed there tomorrow.

 

[Neurobit]

Not sure if I'm late to the party or not, but...I was just told by someone I trust at the dealership I purchased my truck from, he has been my "Mopar Parts Guy" for the better part of 15 years, that all DT Rams will self calibrate the odometer through GPS after 1K miles after a tire size change. I asked if he was 100% certain, and he confirmed. We shall see, getting 285/55R22's installed there tomorrow.

There is no mention of this on my service manual anywhere, so I’d venture to say your guy is totally clueless on this.

Cheers,

 

[Dookie]

It came about by me offering to pay to have them do it, he came back with this. The dude isn't a BS type guy, which is why I like to deal with him. I'll be able to prove this one way or the other and will and will report when I do. NBD, if it doesn't I'll buy the RC tool and do it myself.

 

[Neurobit]

It came about by me offering to pay to have them do it, he came back with this. The dude isn't a BS type guy, which is why I like to deal with him. I'll be able to prove this one way or the other and will and will report when I do. NBD, if it doesn't I'll buy the RC tool and do it myself.

Totally. Let us know what you find.

 

[Dookie]

Went from stock Goodyear 285/45R22 (32.1" dia.) to Yokohama 285/55R22 (34.8" dia.).
After tires installed yesterday, my wife drove it to me to vehicle swap at my office, which is about 15 miles. After work I drove it home, on the drive home I plugged the phone in for Carplay and pulled up the Waze App., if you are familiar with the app., it shows MPH based on GPS and it was dead-on accurate with the speedometer. I texted this "news" to my guy at the dealership, and he responded with "Did you doubt me?" I told him yes, I did...and for good reason, that he was wrong. It didn't take 1k miles...lol.

 

[Dusty1948]

Went from stock Goodyear 285/45R22 (32.1" dia.) to Yokohama 285/55R22 (34.8" dia.).
After tires installed yesterday, my wife drove it to me to vehicle swap at my office, which is about 15 miles. After work I drove it home, on the drive home I plugged the phone in for Carplay and pulled up the Waze App., if you are familiar with the app., it shows MPH based on GPS and it was dead-on accurate with the speedometer. I texted this "news" to my guy at the dealership, and he responded with "Did you doubt me?" I told him yes, I did...and for good reason, that he was wrong. It didn't take 1k miles...lol.

I see you have a Laramie with the Level 2 package. I believe that includes the 12 inch Uconnect screen. Does it also include the option Maps feature?

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: 031506 miles.

 

[Ellisstrong]

I went from 285 45 22 to 315 40 26 over 3 Inch difference and had the same exact thing happen I swear! Checked it with waze and a speedometer app and thought I was crazy

 

[Ellisstrong]

I went from 285 45 22 to 315 40 26 over 3 Inch difference and had the same exact thing happen I swear! Checked it with waze and a speedometer app and thought I was crazy

I also am back on my 285 45 22 because I sent one of my rims back and it’s still spot on...

 

[Neurobit]

I went from 285 45 22 to 315 40 26 over 3 Inch difference and had the same exact thing happen I swear! Checked it with waze and a speedometer app and thought I was crazy

That’s great to hear. Def an undocumented feature.

 

[Ellisstrong]

That’s great to hear. Def an undocumented feature.

But someone I know says his is off on his limited when he went to 35’s

 

[Dookie]

I see you have a Laramie with the Level 2 package. I believe that includes the 12 inch Uconnect screen. Does it also include the option Maps feature?

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: 031506 miles.

Meaning navigation? Yes. It has Navigation.

 

[Dusty1948]

Meaning navigation? Yes. It has Navigation.

Thank you. I'm curious if the GPS correcting speedometer feature is unique to only those with navigation.

Hope you and yours are in good health in Louisiana.

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: 031506 miles.

 

[RebelWraith]

Thank you. I'm curious if the GPS correcting speedometer feature is unique to only those with navigation.

Hope you and yours are in good health in Louisiana.

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: 031506 miles.

Nope, my Rebel 12 with nav would not compensate for 35's. Stayed consistently 3 mph off. Had to use AlfaOBD to change it and when I installed the DiabloSport T2 went back to stock settings in AlfaOBD and used the T2 to change the tire size.
My guess is it can compensate for factory sizes and that's it.

 

[Dusty1948]

Nope, my Rebel 12 with nav would not compensate for 35's. Stayed consistently 3 mph off. Had to use AlfaOBD to change it and when I installed the DiabloSport T2 went back to stock settings in AlfaOBD and used the T2 to change the tire size.
My guess is it can compensate for factory sizes and that's it.

Yeah. There's probably a limit of the system since most tires in the 1500 recommended range are between 30 and 32 inches.

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: 031506 miles.

 

[Dookie]

Thank you. I'm curious if the GPS correcting speedometer feature is unique to only those with navigation.

Hope you and yours are in good health in Louisiana.

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: 031506 miles.

Thanks...My family and co-workers and their families are all doing fine. Only COVID case I have first-hand knowledge of is one of my BIL's, his fever lasted a week, and was diagnosed 3 days into symptoms, he has since made a full recovery and had a Tee time Wed. morning. He is 56 years old fit and healthy but has had triple bypass about 2 years ago. Thanks again, and I hope you and yours are/stay safe and healthy.

Back on topic, my new tire size is 34.8" unmounted (Yokohama Spec) and mounted they are right at 34" (Dookie Spec). When I asked my guy if it was because of my model and trim level, he said no, ALL new DT Rams will do this. I know for a fact mine did, but don't know why others do not.

 

[Dookie]

I snapped a couple pics, first one is just steady foot on pedal 42MPH, and second is with cruise control on set at 48MPH. You can see both Waze GPS MPH (upper right-hand corner on screen) and odometer...Just in case people thought I was FOS.

 

[Dusty1948]

I snapped a couple pics, first one is just steady foot on pedal 42MPH, and second is with cruise control on set at 48MPH. You can see both Waze GPS MPH (upper right-hand corner on screen) and odometer...Just in case people thought I was FOS.

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.