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Big Tires= Big Fuel Consumption????????

Discussion in 'The Garage' started by 1985K20, Mar 17, 2005.

  1. 1985K20

    1985K20 1/2 ton status

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    Ok i know lots of yas are running big blocks and diesels in your rigs...here's my question!:Is bigger cubic inch engines absorbing the crazy fuel milleage increase with big tires(33's and over)???

    friend of mine told he seen very little difference with small or big tires with a 6.2 diesel...

    I know my little 305 burns just about twice as much when i put my 35's on, but buddy's telling me he sees no difference small or big tires with a 366 BB..

    Are they bull$h*tt*ng me or is it true?

    :thinking:
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I get 16.5 mpg on the freeway pushing 39.5" TSL's with my 6.2. That's without an overdrive, and from what I have heard from other 6.2 owners that are turning about the same rpm's as I do their mileage is about the same...maybe slightly better. The 6.2 doesn't really seem to care about the larger tires, just the actual rpm's. If I could get the rpm's down I could pick up a few mpg.

    Rene
     
  3. blackblazer717

    blackblazer717 1/2 ton status

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    i always say its in the gearing!!!
     
  4. 4trolls

    4trolls 1/2 ton status

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    Im running 39.5s with 4.10 gears and a stock 350 with no noticable change in mpg in my 78 suburban
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    My dads K20 is running a 454 with 33's, and it gets the same in the city as it did with the 350. Freeway is about 1-2MPG less. 4.10 gears, gear vendor overdrive.


    Lots of factors, contact patch, tire diameter, vehicle height, etc.
     
  6. joez

    joez 1/2 ton status

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    With my 6.2, i dont notice much difference between the 33" radials and the Q78's. Its still slow as crap and gets at or over 20 mpg depending on how i drive it.
     
  7. r_pogo

    r_pogo Registered Member

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    Tire Pressure & MPG

    On a road trip it might help increasing the tire pressure a bit.

    On several cars/trucks I've owned I have had a 1-2 mpg increases by bumping up the pressure 4-5 or so psi over the sticker while still under the maximum indicated on the side of the tire. This also make them run a bit cooler and wears more on the center to compensate for wear on the edges that happens in all the city dirving.
     
  8. 82K5_6.5L

    82K5_6.5L 1/2 ton status

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    i just went from 33's and stock 3.42 gears, to 35's and 4.10's... man what a difference!! more power, better mileage, better everything!!! and thats with the 6.5L, it feels alive again!!! :p: probably averaging around 16-17mpg..
     
  9. Zeitler

    Zeitler Registered Member

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    i wonder how i'm gonna feel after this:

    from 32's & 2:73 to hm have not decided what tires yet but 4:56 gearing :D :D

    problably gonna feel like i'm still in 1st gear!!!
     
  10. k20

    k20 3/4 ton status

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    I went from 33x12.50s(measured out at about 32) and a 350tbi, went to a 496mpfi and 35x14.50's, and my mileage went from 8 to 10-11.
     
  11. Bhintz

    Bhintz 1/2 ton status

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    exact same thing here
     
  12. Ned Kelly

    Ned Kelly 1/2 ton status Premium Member

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    454/TH400/4.10 diffs/39.5's I get 10-11mpg hwy (best at about 2200rpm) and 7-8mpg in town.
     

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