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Discussion Starter · #1 ·
I'm hoping someone can help me, I am having the Mopar 4 inch lift put on my 2010 Ram 1500 and need to calibrate my speedometer for the 37 inch tires.

The dealership can only calibrate up to a 33 inch tire and said that I need to buy an aftermarket calibrator to do it for the 37's. The only catch is that many of the calibrators change the actual programming of the truck which voids the powertrain warranty, which would make choosing the Mopar 4 inch lift over the 6-inch Superlift which is what I really wanted, a moot point.

Hypertech has an inline speedometer calibrator but they do not make one for my truck. Are there any other products out there that calibrate the speedometer without changing the computers programming? Does anyone else have a solution to this problem?

I have to have an accurate speedometer because of where I live and where I work, there are cops EVERYWHERE.
 

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with my last truck, i ran larger tires than the speedometer/odometer was calibrated to. I had asked the tire shop, Discount Tire, what the speed difference was, they have a chart in their computers software that shows the difference. Then i took that info with me, a few days later I had a friend that had a correctly calibrated vehicle follow me onto the freeway ( thats like your turnpikes & Interstates). I took the vehicle up to speed & held it at the posted speed for a couple miles, & after that, I took the info into consideration.
My odometer was off 3 miles for every 100 miles & I charge by the mile on my invoices & took that into the calculation

I have ridden my Harley without a speedometer since 1986, by just going with the flow of traffic
 

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I had the same problem with my truck but my dealer did the calibration for me and im running 37s with the 4in mopar lift on a 2010. they actually gave me the speedo calibrator. im deployed right now but i can get my friend to check what brand it is if your interested. im not sure if the warranty is different from down in the states but i live in albert, canada
 

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Discussion Starter · #4 ·
Thanks, I actually went with the Hypertech Speedometer Calibrator, it is accurate, I tested it with my wife's GPS. The only pain is that I have remove the calibration each time I take it in and then put it back on so it won't be erased if they flash the truck's computer.

One thing I do know is that you have to calibrate it based on the actual tires height with the weight of the truck sitting on it, don't calibrate it for the size on the side of the tire it won't be accurate.
 

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I'll have to read up on mine alittle more when i get home, thanks for the heads up. My truck is bang on right now i tested it beside my YZF-R1 with the digital speedo after i put the lift on and had it calibrated.
 

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1. just use a window/dash mounted Garmin for your speed.

2. get someone to drive next to you at a few different speeds and tell you how fast you are really going. then you can just interpolate for the inbetween speeds.
 

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Discussion Starter · #8 ·
do you have NAV or factory command start?
if so did you pull fuses and which ones?

thanks
Richie
I have both, looked into pulling the fuses, couldn't figure out which ones they were so said screw it and just hooked the calibrator up. It worked fine. I think they tell you to pull them so there is plenty of battery for the calibrator but the battery should have enough juice even with them plugged in. Worked for me.
 
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