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Thread: 2004 2500HD tire tuneing

  1. 01-21-2011 #1
    jacagle
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    2004 2500HD tire tuneing

    I can NOT for the life of me get the speedo corrected.

    Going 50 mph as indicated on the speedo and aswell as the computer, i am actually going 46. Friend who is a cop clocked me and also i was on my GPS. GPS agrees with police radar. (to verify that the needle wasn't removed and replaced incorrectly previous to me owning the truck i also ran the HPT scan tool and it agreed with speedo needle).

    I had a diablo tuner before HPT, the handheld decide to crap the bed on me so the "stock" tune i read when I got HPT was actually a diablo tune, but i have compared my diablo stock tune to a repository tune and i could not find anything at all that was different between the two.

    I am going from the stock 245/45/16's to a 285/75/16.
    the 285's measure 32.8 diameter.
    BUT, i can put in any number and I STILL get the same readings on the speedo, nothing I do has made a change.

    Am I missing a critical step somewhere here?!
    The last three years my speedo has been approx 9-10% fast, which I would assume the odometer is affected also. That runs my milage that I have put on up just that much more.

    Truck currently sits at 77K miles, which is ACTUALLY 72K miles...
    2000 Camaro Z28- stock motor. P/S LT's, TSP TD bullet style mufflers,de screen maf, LID and K&N filter. 2.73's
    180,000 miles and going strong!!

    2004 Silverado 2500HD- stock 6.0, drop in K&N filter, 285-75/16 sport king A/T's.
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  2. 01-21-2011 #2
    u00bse1
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    When i did my duramax i had to do "trial and error" on the PPM section VSS section of the speedo. I was not able to get the speedo to change with the tire revs per mile or size section of that table. I don't know if HP tuners has a bad table here or what. I know EFI live is differant and it works as it should. But anyway once i got my speedo working it kinda just blew it off since it works great now. I verified my speedo on a GPS at mutiple vehicle speeds. My PPM is 98000 and I run 265/75/16 up from the stock 245/75/16. If you do a simple scale off these two numbers you will without be a lot closer that you are now.

    Hope this helps. I know i was getting pissed and had a headache when i was done messing. Sure you are the same.

    Might also turn in a ticket and refferance this post to fix the software bug (if there is a bug) since this has affected two trucks for sure now.
    Last edited by u00bse1; 01-21-2011 at 04:09 PM.
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  3. 01-22-2011 #3
    Google
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    use this..




    ..
    Last edited by Google; 04-24-2011 at 08:35 AM.
    We Can Fix Your Bricked PCM Or Your YYYYYY OS ID
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  4. 01-23-2011 #4
    jacagle
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    Thanks BOOBle, i mean Google.....

    I'll have to check this out tonight when I get home.
    2000 Camaro Z28- stock motor. P/S LT's, TSP TD bullet style mufflers,de screen maf, LID and K&N filter. 2.73's
    180,000 miles and going strong!!

    2004 Silverado 2500HD- stock 6.0, drop in K&N filter, 285-75/16 sport king A/T's.
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  5. 01-25-2011 #5
    jacagle
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    ok, well...
    I changed the numbers to what that table said to change them too, well as close as HP would let me. couldnt do 2521.01, closest i could get was 2520.99,
    also couldnt do 100841, it was either 100840 or 100842.

    no combination I used made any effect.... this is damn frusterating.

    any other Ideas??
    2000 Camaro Z28- stock motor. P/S LT's, TSP TD bullet style mufflers,de screen maf, LID and K&N filter. 2.73's
    180,000 miles and going strong!!

    2004 Silverado 2500HD- stock 6.0, drop in K&N filter, 285-75/16 sport king A/T's.
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  6. 01-25-2011 #6
    u00bse1
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    If you changed the PPM section it should work. I have personally done an 03 and 04 this way. Where did you get the 100840 from? That is very close to stock on a 245/75-16 tires with 3.73 axle. Stock is like 101008. When i look real quick at the 285/75-16 tire and allow for some general squish from the weight (tire SLR) i get about a 32" tire which is 94034 with a 3.73 axle. If you have the optional 4.10 axle then it would be 103363 PPM. Make sure you change the ppm section. I haven't seen the tire size / tire revs per mile only work either.
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  7. 01-28-2011 #7
    jacagle
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    Thanks u00bse1, that got me to 2 mph under speedo reading. just enought to be really accurate and also wont get me in trouble.

    Google- That spreadsheet didnt quite work, might look into the calulations it uses?? But thanks for the help!!
    2000 Camaro Z28- stock motor. P/S LT's, TSP TD bullet style mufflers,de screen maf, LID and K&N filter. 2.73's
    180,000 miles and going strong!!

    2004 Silverado 2500HD- stock 6.0, drop in K&N filter, 285-75/16 sport king A/T's.
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  8. 01-29-2011 #8
    u00bse1
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    Quote Originally Posted by jacagle View Post
    Thanks u00bse1, that got me to 2 mph under speedo reading. just enought to be really accurate and also wont get me in trouble.

    Google- That spreadsheet didnt quite work, might look into the calulations it uses?? But thanks for the help!!
    Just FYI. The spreadsheet does work. I got the numbers i gave you off it. If you need to tweak your speedo in and need help just IM me.

    Glad you are close now. 2mph is ok, a lot of OEM setups seem to be 1-2 off and is accepted. On thing to think of on a truck is how you use the truck. If you are always empty, set the speedo there. If you run with 3000 lbs in the bed the tires will squat even at 80psi, so you can tweak it there. That is why a variance of 2mph is acceptable.
    Last edited by u00bse1; 02-07-2011 at 07:52 PM.
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  9. 02-05-2011 #9
    jacagle
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    Ahh I see now. I must have skipped right over you calulating for tire "squish".
    I was useing the hpt unit conversion calulator and inputting 32.8 into the spreadsheet.

    Anyways, It works great now. if only i would have known the speedo was off 3 years ago i could have prevented those extra 5K miles that dont really exist on the truck. (
    2000 Camaro Z28- stock motor. P/S LT's, TSP TD bullet style mufflers,de screen maf, LID and K&N filter. 2.73's
    180,000 miles and going strong!!

    2004 Silverado 2500HD- stock 6.0, drop in K&N filter, 285-75/16 sport king A/T's.
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