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Thread: 2006 Cummins Speedo Calibration

  1. #1
    Potential Tuner
    Join Date
    Sep 2016

    2006 Cummins Speedo Calibration


    I have been trying to get my speedo corrected on my 2006 Cummins with 35" tires. I have changed the Pulses per mile as well as the Tire revolutions per mile using the formulas I have found on the forum. So far I haven't seen any change when I go out to compare the speedo to GPS. Am I missing something or doing something wrong?

    Thank you,

  2. #2
    Potential Tuner
    Join Date
    May 2019
    Have you figured this out? I am trying to get this figured out as well...

  3. #3
    what did you end up using for tire rev? I just switched to 35s and calculated 593 tire revs per mile which is over double of the factory 250?
    05 qclb nv5600

  4. #4
    found this in another thread, is this what you tried?

    Adjusting the speedo is easy. You take the stock size tire. Change it to inches to make it easier..

    In my case 05 Dodge ram diesel came with 31.5 inch tires

    I got 35 inch tires.

    You take 31.5/35 = .9

    Take .9 and multiply it by the VSS / Mile setting (10% bigger overall)

    8000 *.9 = 7200

    Calculation is always (Original Tire Height/New Tire Height)*VSS/mile.

    The theory is your gonna see 8000 pulses per mile because your tires are 31.5. You should see less per mile if you have bigger tires, and more if you have smaller.

    Hope this helps! Worked great for me.
    05 qclb nv5600