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Question about Gears and Tire size.. i want to test something

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Silver84k5, Apr 24, 2002.

  1. Silver84k5

    Silver84k5 1/2 ton status

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    i seen this posted on here awhile ago, i need to know what tires size to run with 3.73 gears, to make the equivelent of running 39.5's and 4.88's, or 39'5s and 5.13, could anyone help me on this?
     
  2. 55Willy

    55Willy 3/4 ton status

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    new tire divided by new gears, x old gear
    39.5 / 4.88 x 3.73= 30.1"
    39.5 / 5.13 x 3.73= 28.72"
    what tranny do you have?
    with overdrive you can step up to the next set.
    my 2 cents would be 4.88's but if you have overdrive or don't care for high rpm's on the freeway go with 5.13/forums/images/icons/cool.gif
     
  3. Silver84k5

    Silver84k5 1/2 ton status

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    hmm. so with 38's and 3.73 i feel sluggish, with 39.5's and 4.88's would be i be able to chirp tires without turning on pavement? my motor has between 280 abnd 300 horse i think, and i got th350....
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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  5. BAJA_BLAZER

    BAJA_BLAZER 1/2 ton status Author

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    I have a great Excel Spreadsheet that I developed for our race team that compares 5 different Transmissions, Rear end Gear Ratios, and Tire Sizes. You put in the gear ratios of your transmission and rear end and tire size and it shows you the speeds at different RPMs and graphs the results. You can compare 5 different combinations at once. Any one interested in a copy can PM me with there email address and I'll send them a copy.
     
  6. Silver84k5

    Silver84k5 1/2 ton status

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    Damn the lowest a 14ff can go is 5.13 that sucks, cuz i need 5.71's for more power, is there a reason that 14ff's have such low options on lockers and gears? i mean there are more 14ff's it seems like then d60's wtf is the problem? Thx for responses
     
  7. BurbinOR

    BurbinOR 3/4 ton status

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  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Yep, that's the limit for the C14. And that is plenty low (usually too low) for the factory applications. It's just nut cases like us running 40"+ tires that start having problems. Bottom line is, if you want lower gears, go to a Dana 70. That's pretty much the only reason you would want to run the D70 but, if you need it (or think you do) then that is the only option without going to something more exotic.
     

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