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Re-Calibrate speedo

Discussion in 'Chevy Trucks' started by DJ Contracting, Oct 7, 2010.

  1. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    I replaced my 265 75 R16 tires with 305 70 R16 tires and was wondering if my 99' NBS truck's spedo is cable/gear driven or would I need to use a scan tool to re-calibrate the speedo, my speedometer is now 3 mph off and so my miles also don't register the correct mileage.
     
  2. brad96z28

    brad96z28 PlowSite.com Addict
    Messages: 1,526

    tech 2 or maybe aftermarket programmer.
     
  3. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    So a snap on scan tool won't/can't re-calibrate it?
     
  4. brad96z28

    brad96z28 PlowSite.com Addict
    Messages: 1,526

    Im not sure sure I have not used snap on since the old brick scanners.
     
  5. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    Is a tech 2 a gm tool?
     
  6. Q101ATFD

    Q101ATFD Senior Member
    Messages: 277

    Yes, it's a GM tool - but don't buy one just to recalibrate the speedometer. Some GM dealers will recalibrate for you with the Tech 2 (some free, and some charge), and some won't do it at all, or won't even know how to do it. Most aftermarket/handheld programmers (Hypertech, Edge, Superchips, etc...) will allow you to change the speedo. Keep in mind, that none of them - even the Tech 2 can change the tire size used for the ABS computer.
     
  7. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    And you won't adjust it by only 3 MPH with a Tech II and a factory re-flash as you only have a few choices in axle ratios and none of them will be correct for only a 3 MPH adjustment. Aftermarket handheld or custom tune are your only real options.