1. Welcome to Tundras.com!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tundra discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Tundra owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

35's.. And the Speedo is Close Generous GPS? Luck? or did the dealer adjust?

Discussion in 'Wheels & Tires' started by niscur38, Feb 21, 2019.

  1. Feb 21, 2019 at 4:57 AM
    #1
    niscur38

    niscur38 [OP] New Member

    Joined:
    Jan 2, 2019
    Member:
    #23832
    Messages:
    59
    Gender:
    Male
    So after all the calculators and comparison going from the 275/55/20 BS Alenzas (31.89") to 35x11.5/20 Nitto TG G2's (34.53") I was expecting the speedo to be off about 8%. Finally got around to using an ipotato app to check speed via GPS this am on the drop off to school.

    It seemed that the GPS and the Speedo were in agreement the whole way. Only got up to 60 in the short drive but it appeared to be about dead nuts where I would have expected the GPS to show a faster speed vs the speedo starting at about 40-45mph.

    Can the dealer adjust tire size etc via tech stream? I had them do the mounting/balance/alignment after the lift. So, did I get lucky, should I not trust the app, or wait until I take it to work and start hitting 70-80?
     
  2. Feb 21, 2019 at 5:36 AM
    #2
    Tundra234

    Tundra234 New Member

    Joined:
    Nov 30, 2018
    Member:
    #22402
    Messages:
    16,057
    Gender:
    Male
    First Name:
    George
    Florida
    Vehicle:
    2020 Tundra DC SR5 Barcelona
    Alot of them
    I ran 275/70/18's and mine was off. I just recently went to the 285/70 and it is dead on with the GPS and I did not make any adjustments with the hyper tech calibrator. It really varies from tire to tire.
     
  3. Feb 21, 2019 at 5:41 AM
    #3
    TundraMcGov.

    TundraMcGov. Your friend. Your foe. Not yo Ho.

    Joined:
    Nov 23, 2018
    Member:
    #22089
    Messages:
    2,134
    Gender:
    Male
    First Name:
    Jofus
    Burpinham, Babalama
    Vehicle:
    2017 Super White DC 4X4 Tundra
    Your circumference math is correct at an approx. 8% difference. I would have expected a difference to show up on the speedo.

    But the answer to your query is "yes" the dealer can adjust the internal MPH calculation parameters for the new conditions.
     
  4. Feb 21, 2019 at 7:39 PM
    #4
    LT75

    LT75 Seasoned Pro

    Joined:
    May 27, 2018
    Member:
    #15633
    Messages:
    1,479
    Gender:
    Male
    Saint Charles, IL
    No mods yet
    Only with an inline hypertech. Cost $200 so I doubt it if he didn’t pay for it. You cannot program through the obd port. Or at least that’s what I was told. Hypertech needs to stay behind dash.
     
  5. Feb 21, 2019 at 8:14 PM
    #5
    Juanjoolio007

    Juanjoolio007 New Member

    Joined:
    Mar 4, 2017
    Member:
    #6618
    Messages:
    2,085
    Gender:
    Male
    First Name:
    George
    Oregon
    Vehicle:
    2019 Silver Sky Platinum Crew Max
    Bed Rug, Tonneau cover, Window visors, Console organizer, Weather Tech's
    Your math is correct. It should be off. I used to have a damn picture of my corrected speedometer with my bullydog so people could see the difference. I can't find it and now my stupid hdmi cable is broken.

    The bullydog won't correct. I have the hypertech for that. The bullydog just gets its speed input prior to the unit.

    Don't know anything about that Techstream software stuff.
     
  6. Feb 21, 2019 at 8:22 PM
    #6
    neirbot

    neirbot New Member

    Joined:
    Dec 10, 2018
    Member:
    #22825
    Messages:
    161
    Gender:
    Male
    I'm only off by 1-2% with my 34's. I thought it would be more. Not enough to worry about.
     
  7. Feb 25, 2019 at 4:01 AM
    #7
    niscur38

    niscur38 [OP] New Member

    Joined:
    Jan 2, 2019
    Member:
    #23832
    Messages:
    59
    Gender:
    Male
    Just updating this...speedo was off by about 2mph all the way to work this am. Everything from about 60 and up was off by about 2mph.
    Set the CC at 78 and the GPS was showing 80.
     
  8. Feb 25, 2019 at 5:43 AM
    #8
    Netmonkey

    Netmonkey Don't be a Dumbass

    Joined:
    Mar 21, 2016
    Member:
    #2971
    Messages:
    1,482
    Gender:
    Male
    Georgetown, TX
    Vehicle:
    2016 Texas Edition, 5.7, CM, MGM
    Icon stage 2 lift, 295 60 20 nitto ridge grapplers, fuel kranks, TRD dual exhaust, TRD rear sway bar
    I went from 275/55/20 to 295/55/20 and I expected the same thing... the speedometer to be off by a certain percentage. However, when drove with my garmin GPS, I verified that the speedometer was actually dead-on accurate with the new tire size. so that means that the speedometer was showing the incorrect speed with the original tire size.
     
  9. Feb 28, 2019 at 10:35 AM
    #9
    SoCalTundy

    SoCalTundy Member since 2017

    Joined:
    Nov 8, 2018
    Member:
    #21476
    Messages:
    410
    Gender:
    Male
    First Name:
    John
    Icon Shocks. Total Chaos UCA. Deaver u748 TC shackles Flowmaster super 50. Diode Dynamics fogs. 5.29 Revolution Gears. SSW 17" wheels on BFG 35x12.5
    Do you have any pictures of your truck with the 35x11.50r20s? The price difference between the 11.50 and 12.50 is a few hundred bucks and now I’m considering those.
     
  10. Feb 28, 2019 at 1:30 PM
    #10
    niscur38

    niscur38 [OP] New Member

    Joined:
    Jan 2, 2019
    Member:
    #23832
    Messages:
    59
    Gender:
    Male
    Its up there in the wheels and tire thread that pinned at the top.
     
  11. Feb 28, 2019 at 1:38 PM
    #11
    SoCalTundy

    SoCalTundy Member since 2017

    Joined:
    Nov 8, 2018
    Member:
    #21476
    Messages:
    410
    Gender:
    Male
    First Name:
    John
    Icon Shocks. Total Chaos UCA. Deaver u748 TC shackles Flowmaster super 50. Diode Dynamics fogs. 5.29 Revolution Gears. SSW 17" wheels on BFG 35x12.5
    Would appreciate the link. Don’t know what thread you’re referring to.
     
  12. Feb 28, 2019 at 2:30 PM
    #12
    Cement

    Cement ...

    Joined:
    Dec 6, 2018
    Member:
    #22667
    Messages:
    562
    Gender:
    Male
    First Name:
    Jason
    Vehicle:
    2019 Cement Trundra TRD
    On my 2019, I went from 275/65R18 to 295/70R18 and the speedo vs my iphone GPS has me within 2mph at 75. I expected it to be a lot worse.
     
  13. Mar 1, 2019 at 3:26 AM
    #13
    niscur38

    niscur38 [OP] New Member

    Joined:
    Jan 2, 2019
    Member:
    #23832
    Messages:
    59
    Gender:
    Male

Products Discussed in

To Top