Speedometer calibration

Lake Bum · Apr 17, 2019

I recently went up to a 35” tire and not only is my speedometer off by 3 mph, but the truck often does not want to go into 8th gear. My question is on my 2018 Ram 1500, what’s my options for speedometer calibration? Thanks in advance!

Pitbull24 · Apr 17, 2019

You can use a tuner to adjust tire size.

If you're not interested in a full tune check out Hypertech. Before tuners were available for my '15 I bought this:

http://www.hypertech-inc.com/SpeedometerCalibrator.aspx

CincyZach · Apr 17, 2019

Some dealer's will change it for you. Of course they will charge you for it.

TXRAM16 · Apr 17, 2019

I picked this up from Rough Country for $150. Easy to program and works great.
https://www.roughcountry.com/speedometer-calibrator-90019.html

JB1 · Apr 18, 2019

Pitbull24 said:
You can use a tuner to adjust tire size.

If you're not interested in a full tune check out Hypertech. Before tuners were available for my '15 I bought this:

http://www.hypertech-inc.com/SpeedometerCalibrator.aspx

^^^That’s what I used on my 2017

There’s a new way to do it using AlfaOBD if your comfortable doing it this way.

https://www.ramforum.com/threads/tire-size-change-alfaobd.129984/

VF_Mike · Apr 18, 2019

CincyZach said:
Some dealer's will change it for you. Of course they will charge you for it.

Did not know that about dealers. I either used a tuner to change or the shop that did the install would calibrate.

Sent from my SM-G965U using Tapatalk

CincyZach · Apr 18, 2019

VF_Mike said:
Did not know that about dealers. I either used a tuner to change or the shop that did the install would calibrate.

Sent from my SM-G965U using Tapatalk

Thought I would mention it in case someone didn't want to do it themselves.

VF_Mike · Apr 18, 2019

Thanks for that. Good info.

Sent from my SM-G960U using Tapatalk

Graygoose · Apr 18, 2019

Ditto on the Rough Country, I need one now to fix mine . I used one on my 2015, took like 5-10 minutes, plus it can read codes.

Lifted2wd · Apr 18, 2019

Lake Bum said:
I recently went up to a 35” tire and not only is my speedometer off by 3 mph, but the truck often does not want to go into 8th gear. My question is on my 2018 Ram 1500, what’s my options for speedometer calibration? Thanks in advance!

On my 35's and 37's I never had issues going into 8th. Do you have a CEL on or ECO disabled.

rwhjr · Apr 20, 2019

Lifted2wd said:
On my 35's and 37's I never had issues going into 8th. Do you have a CEL on or ECO disabled.

Yeah I’ve got 3.21 with 35s and it’ll have no problem going into 8th at a reasonable speed. I guess it’s truck by truck but I’m always surprised/confused when anyone says 35s have prevented shifting into 8th......

CincyCuda68 · Apr 20, 2019

Lake Bum said:
I recently went up to a 35” tire and not only is my speedometer off by 3 mph, but the truck often does not want to go into 8th gear. My question is on my 2018 Ram 1500, what’s my options for speedometer calibration? Thanks in advance!

Alfa odb is a better value than a speedo corrector or a tuner (if you have a gasser)

H1Chester · May 28, 2019

I am going to a smaller diameter, and fatter tire. From stock 275/60R20 to 305/40R22.

I will ask the dealer if they can do it before shelling out for one of these. Dealer will probably still be cheaper...

WTM75 · May 29, 2019

I used AlphaOBD. Pretty easy, just follow the directions in the thread in the DIY section.

Speedometer calibration

Lake Bum

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Pitbull24

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CincyZach

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TXRAM16

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JB1

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VF_Mike

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CincyZach

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VF_Mike

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Graygoose

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Lifted2wd

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rwhjr

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CincyCuda68

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H1Chester

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WTM75

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