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Thread: Did I do this right????

  1. #1
    Potential Tuner
    Join Date
    Jun 2008
    Posts
    5

    Did I do this right????

    I just installed HPT for my 04 Silverado with a 4.8L and 5sp tranny. I notice that I could not change my tire size, looking through the fourm I found the manual way to change it. I have 255/45/R20 (29) wheels and my Stocks were 235/75/R16 (29.9). 3.73 rearend.

    Heres what I did

    255/45/R20 29*3.14 (pi) = 91.06 inches

    63360/91.06= 695.80 * 3.73 = 2595.3525 is my trans rev/ per mile



    235/75/R16 29.9*3.14 (pi) = 93.886 inches

    63360/93.886 = 674.86 * 3.73 = 2517.2315

    For my VSS pluse per mile I took 2595.3525/2517.2315=103103
    or is it 2595.3525*40 (rev-trans) which = 103814. Which is correct??????

    When I put these values in the program changed them alittle such as 2595.3525 was change to 2595.3514 and 103103 was changed to 103102
    Why did the program do that??

    Sorry for the long post, Im just alittle confused.

  2. #2
    Супер Модератор EC_Tune's Avatar
    Join Date
    Apr 2003
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    Almost 2000 feet.
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    7,876
    Trans revs/Mile * VSS Multiplier (40 in this case) = VSS Pulse per Mile

    The minor changes are based on the resolution of the vss system itself. And that tiny change won't make any difference.
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