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Considering 35s? 34s? 33s? 32s Here's some tech info for you...

Discussion in '1Gen Wheels & Tires' started by Sal R., May 3, 2017.

  1. Sal R.

    Sal R. Active Member

    This thread is meant to provide some general information regarding some things to consider when adding larger than stock tire sizes and/or aftermarket wheels with specs different stock.

    Here is a general infographic of where interferences will occur with the addition of larger tires/varied wheel offsets:

    First, let's talk suspension and suspension lifts. The suspension is meant to go up and down and are designed to have a max upward travel distance and downward travel distance. OEM tire sizes are designed to clear all the surrounding suspension components and structure at full compression steering lock to lock. The bumpstops located just above the lower control arms are the absolute limiting component of suspension upward travel.

    While suspension lifts (strut spacers, spring/strut combo, coilovers, etc.) are an easy way to gain some clearance between wheel & tire and the surround components and structure AT static ride height, it does nothing for clearance when the suspension cycles upward completely. You'll still get the same max allowable upward travel with stock suspension with all the same interferences from lock to lock at full compression. And when you're off-roading, your suspension WILL cycle upward all the way.

    Naturally, when putting on larger tires, you are effectively reducing the amount of clearance between the tire and the suspension components, fender, inner fender liner, firewall, and frame. How much reduction in clearances that will occur depends on the wheel AND tire combination. And I say wheel AND tire because the specs of the wheel will determine the placement of the tire at static ride height and the tire specs affects the steering turning travel area that is covered from lock to lock.

    The two characteristics that determine wheel & tire placement are wheel backspacing and wheel offset. The lower the backspacing, the more the wheel & tire is pushed AWAY from the wheel hub (wheel sticks out more). The higher the negative offset, the more the wheel & tire is pushed AWAY from the wheel hub (wheel sticks out more).

    Low backspaced and high negative offset wheels create clearance away from SOME surrounding components and structure, but effectively, it only moves the interferences to another location.

    Wheel spacers reduces wheel backspacing (e.g. 4.5" backspace + 1.25" wheel spacer = 3.25" backspace).

    Body lifts create vertical clearance by lifting the actual sheet metal body AWAY from the frame and suspension.

    To create clearance for larger tires using a body lift, a good rule of thumb is 1in for every 2in tire diameter change (e.g. OEM 30s > 35s = +5in diameter change ->2.5-3in body lift).
    Last edited: May 3, 2017
  2. Sal R.

    Sal R. Active Member

    For reference, 265/75R16 (31.25" Tire) 1" from full compression:

    Based on measurements taken when I tubbed for 34s, the wheel upward travel has a ratio of 2:1. Basically, for every 0.5" of travel between the lower control arm to the bumpstop equates to 1" of upward travel at the wheel.

    In the pic below, I still had +2" of usable upward wheel travel before fully cycling the suspension.
    Last edited: May 3, 2017
    Jim Smola and 02SR5SoccerMom like this.
  3. Sal R.

    Sal R. Active Member

    For reference: 295/70R18 (34" Tire) 0.5" from full compression

    Based on measurements taken when I tubbed for 34s, the wheel upward travel has a ratio of 2:1. Basically, for every 0.5" of travel between the lower control arm to the bumpstop equates to 1" of upward travel at the wheel.

    In the pic below, the wheel can travel upward +1", but as you can see, it would interfere with the fender.
    Last edited: May 3, 2017
  4. Jim Smola

    Jim Smola Active Member

    I simply love this post. Thanks so much for all your great input.
    Sequoia4WD and Sal R. like this.
  5. 1down4up

    1down4up New Member

    Just installed some new shoes on the tree. 275-70/17. Fitment is pretty much maxed for tire size. Stock suspension with rear airbags. Just an addition to the thread![​IMG][​IMG][​IMG][​IMG]

    Sent from my SM-G955U using Tapatalk
    Sal R. likes this.
  6. 1stgenoffroad

    1stgenoffroad Member

    That looks good? Are you getting any rub with the factory wheels? It that last photo showing us the full turn?
  7. SR54WD

    SR54WD New Member

    Any more pics? I would love to see the whole truck if possible.
  8. 1down4up

    1down4up New Member

    GTV and SR54WD like this.
  9. Jason Schweitzer

    Jason Schweitzer New Member

    If like a 2 inch or 3 inch. What is the best way to do this. I' like to run 33s on 18inch wheels.

    Attached Files:

  10. Jason Schweitzer

    Jason Schweitzer New Member

  11. Jason Schweitzer

    Jason Schweitzer New Member

    These are the rims I have to put on!! 18inch
  12. Sal R.

    Sal R. Active Member

    To add to this thread, Jose Wong over @expo has a detailed thread regarding tubbing for 35s.

    Wheel spec is OEM LC80 wheels with spacers resulting in a 3.25" backspace. This kind of wheel spec results in a lot of material removed to clear 35s stuffed, lock to lock.




  13. Sal R.

    Sal R. Active Member

    So, what will it take to clear 35x12.5 tires?

    In short:
    1. Wheel must have a minimum 3.5" backspacing to clear the UCA, regardless of wheel width.
    2. Cut away firewall or a 3 inch body lift or a combination of both.
    3. Body lifts will require:
      1. Clearancing the transfer case shifter opening, if you have one.
      2. Moving the front and rear bumper crash bar support upward, which will require cutting and welding
      3. Extending the steering shaft, which require cutting and welding.
    4. New wider fiberglass fenders or trimming the OEM fenders 3-4" to clear the tires.
    • Not an issue if you use a bodylift.
    Last edited: May 21, 2018
  14. mnwanders

    mnwanders New Member

    So the big question I have after seeing this is, did you go to 275-70/17 for the spare too? If you did, how does it fit in the traditional spare spot? Does it fit ok? I'd like to go to this size but I was concerned about the size of the spare.
  15. 1down4up

    1down4up New Member

    Honestly... I didnt do the spare. Still factory . Sorry cant help with that

    Sent from my SM-G955U using Tapatalk
  16. 275/70/17 BFG AT KO2 fits fine in the spare location. I have one there now.
    mnwanders likes this.
  17. mnwanders

    mnwanders New Member

    One more question...I'm heading out west in a few weeks for hunting and I often hear guys say that they recommend 10-ply tires. Are any of you running anything above SL? I will probably put some new tires on here before heading out and was curious about the load range you all use. I was looking at putting on some 265/70/17's to ensure they fit and get load range E tires, probably KO2s or Yokohama Geolanders. Any thoughts on load?
  18. Whocares

    Whocares Member

    Anybody try 285 70 17 in the spare spot?

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