want to fit bigger tires than my 245/75R16

Discussion in 'Tires / Wheels' started by hadtomer, Jan 12, 2019.

  1. tommudd

    tommudd Moderator Staff Member Moderator

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    Must be since I hated the week I drove mine with stock gearing and 265-75-16s , was happy to get power and gas mileage back , plus no more shifting all the time
    I even run 4.10s with 31s on the 03
     
    Last edited: Jan 26, 2019
  2. Zero402

    Zero402 Full Access Member

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    Oh Ill agree on that, gas mileage definitely took a hit.
     
  3. tommudd

    tommudd Moderator Staff Member Moderator

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    with stock gearing and 32s I was getting 14-15, and it shifted all the time even on level ground.
    4.10s went back to 21-22 mpgs, didn't shift as often, and had power like when it was stock
    well worth the 350 it cost me to regear
     
  4. arielflash

    arielflash New Member

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    theoretically speaking, looks like it should be fine...
    considering the following:
    going from 235/75 to 245/75 is +5.2% ( https://tiresize.com/comparison/ )

    looking at the gear ratio / tire size chart at Differential Gear Ratio to Tire Size Guide | Offroaders.com
    you can see that using 3.73 gears combined with almost 31" wheels results a "yellow ratio" - fits with the major power loss you've felt (as i did)
    re-gearing to 4.10 puts you back in the green field - happy happy joy joy ! (as it did to me :)

    245/75 -> 235/85 = +3.9% and 31.7" tire size
    245/75 -> 265/75 = +3.6% and 31.6" tire size

    percentage wise - its a smaller transition than the one in which you've felt a major power loss...
    also, looking at the chart again - seems like 32" wheels combined with 4.11 ratio would still result in a "green ratio"
    so... theoretically speaking - you shouldn't feel the same major power loss you did when going from 235/70 to 245/75 - but thats only theory :)

    currently - I am trying to modify less (less new problems) and enjoy more (go travel and have fun)
    its all up to you and the spare days you've got (or not) to put in this :)

    I guess you already thought of this but in case not - try finding someone with the tire size you want and have a test drive using their wheels...
     
  5. kejobe

    kejobe Full Access Member

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    I'm running 265/70/16's and 3.73 gearing. It does fine, BUT would be a lot better with the 4.10's. My gas mileage sucks, 13-14 mpg's. But since I put the tires on, things have changed and I cannot afford to regear or I would. I've been running this for about 3 years now. It's NOT my daily though, unless the weather is bad or need the trailer (does fine).
     
  6. tommudd

    tommudd Moderator Staff Member Moderator

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    Agree it works for some people for sure.
    I'm anal on a few things on anything I ride or drive, plus my KJ's are the only 4 wheel vehicles I own. I build mine for a 15 mile trip to the hardware store or if my wife is not busy, run the 350 miles down to see her where she is.
    So I want the best ride, best running vehicle I can have all the time. :gr_grin:
     
  7. JasonJ

    JasonJ Full Access Member

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    Have you checked local or online used parts/salvage yard listings? Even if you have to drive an hour or two each way to go pick up the gears, or haul a trailer to bring back 4wd-4cyl axles, if you got them cheap enough, about what Tom stated it cost him, it'd be worth it.

    When I have looked, I have not seen many of the 4cyl 4.10 ratio axles for more than about $200 each, and that'd be with sub-100k miles on them. It's really the fastest, easiest, and most affordable way to do the upgrade. Should be able to do it yourself in a weekend in the driveway.
     
  8. tommudd

    tommudd Moderator Staff Member Moderator

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    Less than half a day to swap front and rear , fun, easy, relaxing day :emotions34::icon_razz:
     
  9. Zero402

    Zero402 Full Access Member

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    Half day to change out both front and rear gears? It's that easy?? Ugh what am I waiting for.
     
  10. JasonJ

    JasonJ Full Access Member

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    Yeah.. now that I think about it.. hell, in the rear, it's what? Driveshaft u-joint, rear shocks, brake calipers or hoses, upper and lower control arms and she'll roll right out.

    Front, cv halfshafts, front prop shaft, couple brackets maybe?
     
  11. tommudd

    tommudd Moderator Staff Member Moderator

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    Rear I pull the calipers , hang them out of the way, disconnect the brakelines let them hang, when all done never even have to bleed the brakes, since I never open them up, e-cables are even easy to disconnect and R&R

    Funny story , I picked up a 4.10 diff with a DTT already installed brought it home. My 21 year old stepson had just arrived from Tanzania, first time in the USA. Never worked on a vehicle or really seen or knew anyone that did. When I told him what we were going to do, and while we were doing it, he never thought it would run again or it would take days. Couple hours later we were out driving around! He couldn't believe it !
     
  12. Zero402

    Zero402 Full Access Member

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    Oh you guys are talking swapping it all out, not just the gears.

    I was thinking about buying new gears, but now I suppose I will just keep tabs on the inventory at the boneyard.
     
  13. tommudd

    tommudd Moderator Staff Member Moderator

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    I swap the whole complete diff out, have on several KJs
    front and rear, fronts take a bit more time but also can do in less than half the time the manual calls for
     
  14. kejobe

    kejobe Full Access Member

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    That's what I need to do, just can't afford sh1t right now. Had job issues just a little over a year ago and we're still trying to get back above water.

    Plus it'll take me a little longer to swap out, I have the factory LSD and it still works great and don't want to lose it, so I'll have to swap the rear gears and front diff.
     
  15. tommudd

    tommudd Moderator Staff Member Moderator

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    Know what ya mean, been through it as well ( back in 2012) , and now just a month ago this job ended, they lost contract, so again looking