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Gearing / RPM Question

Discussion in '2nd Gen. Tacomas (2005-2015)' started by fatsac, Dec 6, 2010.

  1. Dec 6, 2010 at 9:40 AM
    #1
    fatsac

    fatsac [OP] Well-Known Member

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    I have an '07 Offroad and about to order 285 or 295/70/17 tires. With these in place, how much difference in rpms will it make?
    I am right about 2500 at 70 in sixth.
    There must be a calculator somewhere for all of this but if anyone knows, I appreciate it.

    Thanks!!
     
  2. Dec 6, 2010 at 9:45 AM
    #2
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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  3. Dec 6, 2010 at 9:56 AM
    #3
    fatsac

    fatsac [OP] Well-Known Member

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    Katz Leather, heated seats, Tint, KN Filter, OME 887, Camburg UCA, Dakar packs, 17x9 XD, 295/70 Toyo MT w cab mount chop, fender massage, Weathertechs, Black PC steps, skidplate, 2012 grill, Bushwacker painted flares, Nearly every TSB you can think of, TRD quickshift, All-Pro front w/ Skids, 9k winch, Tonneau cover, voodoo tailgate cap...
    That helps. Maybe I'm confused but a bigger tire will kick RPM down, so wouldn't that be better for those of us with the 6spd? I always thought stock gearing was too low anyway. 2500 at 70 sounds much more high strung than my '06 4-runner loping along around 2k at 70.
    Hope this makes sense!
     
  4. Dec 6, 2010 at 10:02 AM
    #4
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    You are correct, taller tires means lower RPM's at the same speed. It's good depending on how you look at it. You're turning lower RPMs but it takes more power to turn the wheels in general. If you feel your Tacoma is geared too low for what you do with it, you'll probably be very happy with the results. I wouldn't expect any MPG increases though if that's where you were going with the lower RPMs.

    FWIW, I'm running fairly high RPMs with my '07 auto as well so it's not just the stick shift.
     
  5. Dec 6, 2010 at 10:17 AM
    #5
    fatsac

    fatsac [OP] Well-Known Member

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    Thanks bud! I'm not worried about gas mileage and just like the sound of everything when under 2500. I drive like an old man anyway...an old man with beefy tires!
     
  6. Dec 6, 2010 at 11:56 AM
    #6
    kram

    kram Well-Known Member

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    URD Short Shifter TSB Leaf Pack, Bilstein 5100s front (1.75") and rear. 285/70/17 Duratrac on Rhino Sidewinders. Weathertech Digifit Floormats
    I have a question. The speedometer reading and RPM relationship will remain unchanged after going to bigger tires won't it? It's only that your actual speed is higher? Or does that get thrown off somehow as well.
     
  7. Dec 6, 2010 at 12:04 PM
    #7
    Pugga

    Pugga Pasti-Dip Free 1983 - 2015... It was a good run

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    I think I'm following what you're asking and you are correct. The relationship between your now inaccurate speedo reading and RPM remains unchanged since it works on ratios. But you are actually moving faster than your speedo is telling you.
     
  8. Dec 6, 2010 at 3:55 PM
    #8
    kram

    kram Well-Known Member

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    .
    Ok, thanks. That's what I thought.
     
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