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Best gear ratio for 40" tires?

This is a discussion on Best gear ratio for 40" tires? within the Offroad forums, part of the General Discussion category; Hey guys, I'm planning on putting some 39.5x18x16.5 Boggers on my truck and I'm wondering what gear ratio I need ...

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    Best gear ratio for 40" tires?


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    Hey guys, I'm planning on putting some 39.5x18x16.5 Boggers on my truck and I'm wondering what gear ratio I need to install. I don't do very much highway driving at all and I rarely go over 55MPH. I want good acceleration! Also, how much does it cost to change the gear ratio? Any help is appreciated, thanks.
    Last edited by datboyroy12; 05-09-2007 at 07:16 AM.

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    Legend HDhoss's Avatar
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    Re: Best gear ratio for 40" tires?

    5.13
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    I'm so much cooler online Mark13's Avatar
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    Re: Best gear ratio for 40" tires?

    7.17 would work wonders:LOL:
    Last edited by Mark13; 05-09-2007 at 06:41 AM.

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    BigRed05
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    Re: Best gear ratio for 40" tires?

    What truck is this going on? Is it a diesel or gas? Do you Tow? What axles do you have?

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    Re: Best gear ratio for 40" tires?

    It's a 2000 Extended Cab Z71, 5.3 gas engine, I don't ever tow anything and I have stock axles as far as I know.
    -"NONO"-

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    Re: Best gear ratio for 40" tires?

    40" boggers are going to destroy your axles. If you're set on running a 40" tire and the stock running gear, I'd get a 40" MTR. Hell, 40" boggers break D60's and you're not even in the same ballpark for strenght.

  7. #7
    BigRed05
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    Re: Best gear ratio for 40" tires?

    Quote Originally Posted by datboyroy12
    I want good acceleration! Also, how much does it cost to change the gear ratio? Any help is appreciated, thanks.
    Ok man, dont mean to bust your bubble or anything. But i think my truck is pushing the limits right now. You will need a new rear axle. Your going to want to put a 14SF axle. I am rebuilding one from a 89 2wd 2500. Now your front end. My buddy derrik Has these on a jeep, Do you know how heavy these tires are? And you are going to have to run a huge offset wheel with wheel spacers. Just thought i would let you know. But 5.13s would be your best bet. And it will cost you between 1,200and 1,800 for gears. You will want a locker in the rear also. Add bout 500 at least. What lift are you going with?

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    Registered User red o4's Avatar
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    Re: Best gear ratio for 40" tires?

    40 inch boggers on independent front end is going to be sudden death. And the rear axle is going to break soon. The best route would be 1 ton front and rear axles.
    04 z71
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    Re: Best gear ratio for 40" tires?

    go with 35's and 4.56 or 4.88....that be a nice setup
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    BigRed05
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    Re: Best gear ratio for 40" tires?

    Quote Originally Posted by burly_bus
    go with 35's and 4.56 or 4.88....that be a nice setup

    Every person and their grandmother has this set up, got to be a little different.

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    Registered User HD4Mud's Avatar
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    Re: Best gear ratio for 40" tires?

    Where would you get 7.17s. The steepest I've seen on the we are 5.38s

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    Re: Best gear ratio for 40" tires?

    I think i've posted this a million times but check out this gear chart

    http://www.4lo.com/calc/geartable.htm

    Quote Originally Posted by BigRed05
    Ok man, dont mean to bust your bubble or anything. But i think my truck is pushing the limits right now. You will need a new rear axle. Your going to want to put a 14SF axle. I am rebuilding one from a 89 2wd 2500. Now your front end. My buddy derrik Has these on a jeep, Do you know how heavy these tires are? And you are going to have to run a huge offset wheel with wheel spacers. Just thought i would let you know. But 5.13s would be your best bet. And it will cost you between 1,200and 1,800 for gears. You will want a locker in the rear also. Add bout 500 at least. What lift are you going with?
    If your gonna go through the time and trouble putting in a new axle might as well go with a 14 FF
    Last edited by taSk; 05-09-2007 at 12:13 PM.

  13. #13
    BigRed05
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    Re: Best gear ratio for 40" tires?

    Quote Originally Posted by taSk
    If your gonna go through the time and trouble putting in a new axle might as well go with a 14 FF
    Not if he wants to keep 6 lug front and rear so he can Rotate his tires. And a 14SF is the strongest 6 lug that is decent priced.

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    Re: Best gear ratio for 40" tires?

    I've snapped a D60 axle with 35x14.50 boggers. 40's are certain death for your axles and tranny if looking for "acceleration"

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    Re: Best gear ratio for 40" tires?

    5.13's for sure. I'd get a 14ff or D60/70ff rear. I'd skip the 14sf because it's strong but still a c clip axle.
    "When life gives you too short of bolts, don't put thinner nuts, replace the bolts."- The_Law

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    Re: Best gear ratio for 40" tires?

    Quote Originally Posted by HD4Mud
    Where would you get 7.17s. The steepest I've seen on the we are 5.38s
    I found them on a site somewhere for sled pulling trucks.

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    Intenionally blank b454rat's Avatar
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    Re: Best gear ratio for 40" tires?

    Go ahead and put them on, just show pics of all the busted peices. Dana's and 9" can run some steep gears, mostly Dana's for industrial equipment. Gonna need a 60 up front, and either a 14ff or a Dana 70 in the rear. If you change your t-case to a pass drop, you can run a GM/Dodge 60 and a D70 rear, you can get steaper than 5.38s.

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    Re: Best gear ratio for 40" tires?

    7.17's exist for D60/70's. 5.38's are the lowest offering for the 14FF and the 8.25 front only goes to 5.13. Id go as deep as you can with 5.13's.

    An 8 lug full floater would be nice, paying for those 6 lug hubs and turning the axle shaft flanges is pricey though.


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  19. #19
    RBz OFFROAD
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    Re: Best gear ratio for 40" tires?

    5.13s and run it till she blows. Boggers are the **** what lift are you gonna run???
    -2003 GMC ECSB 2500HD 4x4 496 8.1L, Allsion, Volant CAI, Helix Power Tower, Granatelli MAF, Dual 3" w/ X-pipe no mufflers/no cats,3" PA BL, 8" Fabtech, Custom Steering with 3/4 Heims, 42 TSL SX IIs, 20x10 MT Classic IIs.

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    Registered User TAHOE GUY's Avatar
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    Re: Best gear ratio for 40" tires?

    An 8 lug full floater would be nice, paying for those 6 lug hubs and turning the axle shaft flanges is pricey though.

    bggnrchvyWhere can I find some 6 hug hubs to put on a 14FF axle and how much? I would like to go with that route my self.

 

 
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