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How Tall of a Tire?

Discussion in 'Early CJ5 and CJ6 Tech' started by Blue CJ6, Feb 10, 2014.

  1. Feb 10, 2014
    Blue CJ6

    Blue CJ6 Member

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    Hey guys. My oldest boy and I were out flexing the old girl this evening to see how much room there is for a taller tire on our CJ6. It's stock with 27 inch tires currently. At full flex, ( other side tire barely touching the ground), it has 4 inches in the back more room from the top of the stuffed tire to the top of the wheel well. It has 4.5 inches in the front more room from the top of the stuffed tire to the rib inside the fender well. Not the outside rim of the fender, but the rib that runs across the inside of the top of the fender. I was thinking of staying with a 9.5 inch width tire so as to not screw up the front fenders when turning and the tire being stuffed up in the fender when articulating.
    If my thinking is correct, I imagine that for every inch of a taller tire, its splits the height by half an inch on the bottom of the tire, and half an inch on the top. You know what I mean? I know its a diameter thing, but in my mind, picturing it on the Jeep, the additional height would be split evenly around the tire. So as it sits, it would be half and inch per side to make an inch. Does this sound right? So if I have 4 inches of room when the tires are fully stuffed in the wheel wells on the top of a 27 inch tire, then I could go with an 8 inch taller tire? That doesn't sound right. Not with stock springs. I was originally thinking of going with a 32x9.50 TSL Bias Ply, which would be 5 inches taller than what's on there now.
    Thanks for your input guys!
    Dave
     
  2. Feb 10, 2014
    piffey263

    piffey263 Active Member

    Medford, OR
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    Before I put a lift on my jeep, I was running 31.11.50 tires. I would get some rubbing in the rear when it articulated, I don't recall having any in front.
     
  3. Feb 10, 2014
    Danefraz

    Danefraz Well-Known Member 2023 Sponsor 2022 Sponsor

    Chico CA
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    I have 32" HDT Hercules for mine. I also have McRuff shackles that add some height.


    Sent from my iPad using Tapatalk
     
  4. Feb 10, 2014
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    About the same, some rubbing against the sides in the rear well when twisted, and on the springs when at full lock on the front, but not a big problem.

    The wheel offset is a factor to consider. Also bear in mind a larger diameter is the same as higher gearing, and will impact speed v. power.

    Your suggested tire sounds good to me.
     
    Last edited: Feb 10, 2014
  5. Feb 11, 2014
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    AFAIK they all rub on the inside of the rear fenders when the wheel is stuffed, even with factory tires.

    The inner diameter of the rear wheel well is roughly 33-34" in diameter, so anything larger than a 33 will need a lot of lift or fender trimming. You also risk catching the front edge of the front fenders when stuffed with that large a tire. If you want 35s, you can cut the rears and fit Wrangler rear flares, and trim the fronts or go with front tube fenders.

    I would expect 32x9.50-15 to need a wider wheel than stock, say 7". You can check with the tire manufacturer on a recommended wheel size.
     
  6. Feb 11, 2014
    Blue CJ6

    Blue CJ6 Member

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    Ok. I got it figured out last night in my head. From left to right, the tire does grow half an inch equally with each inch of increased tire size. But up and down, it visually only increases above the tire because both areas of increase are causing the tire to go only one way, and that's up, because of the tire pushing on the ground. So my max tire size would be 4 inches taller to a 31 inch tire. I'm sure this sounds like common sense to you guys, but I had to get my head around it.
    I did notice, like Tim was saying, that the stock tires did rub on the inside of the front fender when the wheel was turned, and the tire was stuffed. It was hitting the vertical part of the inside of the fender next to the engine. Where the rib comes down near the upper shock mount. The stock tires also rubbed in the rear on the inside of the vertical part of the wheel well, next to the tub.
    31's will be great. Thanks for the help guys!
     
    Last edited: Feb 11, 2014
  7. Feb 11, 2014
    Blue CJ6

    Blue CJ6 Member

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    Do you happen to have any pictures of your Jeep when you had the 31x11.50's on it? There's some where I live for sale, on some good looking rims for a super price. Just not sure about the width. Wondering if it would be a little wide. They're the 31x11.50 LTB Super Swampers on 15x10 Eagle Alloys.
     
  8. Feb 11, 2014
    piffey263

    piffey263 Active Member

    Medford, OR
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    I will put a few pictures up before the lift for ya within next hour.

    keep in mind non super swampers in that width are no longer sold. super swamper is one of few that sell that width now....


    Sent from my iPhone using Tapatalk

    Edit for pictures: all tires are 31X11.5 except drivers rear which I swapped out cause I hit a piece of metal and the tire shop only had 31x10.5
    White jeep has 30x9.5

    [​IMG]
    [​IMG]
     
    Last edited: Feb 11, 2014
  9. Feb 11, 2014
    lynn

    lynn Time machine / Early CJ5 HR Rep Staff Member

    Huntingdon PA
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    Generally speaking, a CJ will accept a 31" tall tire with no lift.
    Minor rubbing can be expected on the springs at full lock(depending on backspacing), and on the tub in the back.

    A 10.50 wide tire works well with a 7" wide wheel. A 3" differential keeps the bead seated while reducing sidewall bulge. Less than 3" differential increases the risk of the bead becoming unseated when aired down. A 4" to 4.5"(maximum) differential can be used, but sidewall bulge increases and contact patch uniformity is harder to maintain (for even tire wear), but works well for keeping the bead seated when aired down.
     
  10. Feb 11, 2014
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Yep, the usual rub points are the front springs and the rear corners of the rear wheel wells at full stuff. Use a wheel with 3 to 3.25" backspacing and the spring rub will be minimal. Just set the knuckle stops. You may need to add a spacer on the rear bumpstops to keep the tires off the tub there. And as Tim said, even the factory H78-15's rubbed on the inner wheel wells.
     
  11. Feb 11, 2014
    Boyink

    Boyink Super Moderator Staff Member

    Tulsa, OK
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    Besides a little scuffed paint I never understood the issue with just letting them rub.
     
  12. Feb 11, 2014
    tomatolane

    tomatolane Lane

    Chattanooga...
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    X2
    I have always used my wide tires and rubbing, as a gauge, like I used to do with my need slider on my leathers, when I raced bikes.

    Once it starts to rub,there is only so far it will go after I reach that point,And the noise almost instantly makes you freeze your foot, and not give it anymore.

    Makes me pop my head out the window to check and see what is going on. :)

    It lets me know where I am at, and how close I am to the limit. :)
     
  13. Feb 11, 2014
    oldtime

    oldtime oldtime

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    My big gripe is that virtually every tire manufacturer mis-represents the actual mounted/inflated diameter.
    Some manufacturer diameter claims are farther off than others but most tires are claimed to be 1" taller than they actually are.
    That implies that a diameter claim of 32" is typically around 31" of actual height.
    Super Swampers are certainly no exception.
    For that reason I suggest the actual inflated tire diameter to be 31" in order to match the rear wheelhouse opening.
     
  14. Feb 11, 2014
    tomatolane

    tomatolane Lane

    Chattanooga...
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    X2 again.

    I am a firm believer in the golden mean as far as looks.

    But any 31 inch tire at any width will work great on any jeep, with the right wheel/back spacing. 31x15.5x15 will fit all day long and not ever rub with the right wheel combo. :)
     
  15. Feb 11, 2014
    Blue CJ6

    Blue CJ6 Member

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    Thanks for the pictures. How did the 11.50's help with stability?
     
  16. Feb 11, 2014
    piffey263

    piffey263 Active Member

    Medford, OR
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    I couldn't tell you because that is the only size that I have used on the jeep. I don't think 1 inch wider would help with stability... it's too small of a value. things like shocks, Dana 30, spring bushings and new steering components would help more in the area of stability.

    start talking things like traction then that inch might help, but I don't think it would that much.


    Sent from my iPhone using Tapatalk
     
  17. Feb 11, 2014
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    What kind of stability are you thinking of? Bias ply tires are more directionally stable than radial, that's why they are still used on trailers.

    Floatation-wise, a fat tire will support more weight on soft ground. But are a steering traction-disaster on snowy pavement.
     
  18. Feb 12, 2014
    Blue CJ6

    Blue CJ6 Member

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    I was thinking that a wider tire would give a wider stance, and be more stable or less tippy. Although, it didnt feel at all tippy when my boy and I were testing out the articulation. It felt very stable. I'll probably end up going with either the Super Swamper 32x9.50 Bias Ply, or the 31x10.50 Buckshot Mudder XMT. The Super Swamper's are $210 per tire through National Tire and Wheel with free shipping, and the Buckshots are $136 per tire with free shipping. Both would be great.
     
  19. Feb 12, 2014
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    My guess is that to get the wide stance you'd want to look at backspacing on the wheels, but then you may need to cut and flare the fenders. In my neck of the woods, a narrow vehicle gets through the rocks and trees better.
     
  20. Feb 12, 2014
    jeep2003

    jeep2003 Well-Known Member

    Upstate NY
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    i run 31x10.5. they do rub on the inner wheel wells in the back at flex . iv added a little bit of spacers till the lugs ran out of thread and that helped a bit. if you get rubbing on the front springs the stops are simple to adjust
     
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