To mini-tub or not?

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by Mr Sunshine, Dec 4, 2017.

  1. Mr Sunshine

    Mr Sunshine Member

    56
    2
    Dec 12, 2016
    Missouri
    I'm wanting to run about a 11"+ wide tire in my 78 Camaro. Probably a 285 x 40R x 18 which is 11.2" wide. Prefer not to roll the lip or modify if possible. But I've read that the largest tire to run in a stock Camaro is 275 x 40R x 17 which is 10.8" wide. I did some measuring on my car and it looks like I could get the 11.2" with proper back spacing etc. I'm measuring from my current tires which are 235 x 60R x 15 and are 9" wide. In photos you can see I have 1" clearance to rear fender lip and 1 5/8" clearance to the leaf spring. That adds up to 11 5/8" total so 11.2" should be just fine. Am I missing something?
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  2. Zulu28

    Zulu28 Veteran Member

    170
    9
    Dec 19, 2013
    Vancouver, BC
    The problem that you'll run into will be finding an off the shelf wheel that you like with the right offset, I'd prefer not to roll or cut the lip so I'll be doing the mini tub install along with suspension mods, keep in mind that it's pointless installing mini tubs unless you're going to move the leaf spring inboard, with a 285 I'd look for the correct wheel offset, with the taller 40 series tire you might have to do something with the seat belt hump, some good threads on max tire sizes no cutting up here.
     
  3. G72Zed

    G72Zed Veteran Member

    386
    22
    Sep 8, 2015
    Canada
    Looking at your math, total clearance of 11.625 - 11.2 (285mm) section width tire leaves you with 0.425, or 0.212 per side!! Add in heavy cornering, spirited driving, rear end articulation on bump, along with leaf spring rubber bushings and rubber/urethane perch pads, IMO, it's going to cut in to your sidewalls.

    If I am reading this right, you would rather install mini tubs than trimming/rolling the wheel lips?? In my experience, the wheel opening lips are way to wide for nothing, and all it does is limit your section width and cuts into the sidewalls!!

    I have a "none" mini-tub Camaro running 295/40/18 street tires and 12x26.5 slicks, even had 305/45/18 MT DR. It's surprising what you can fit in there without going to tubs. JMO.
     
  4. badazz81z28

    badazz81z28 Veteran Member

    14,029
    94
    May 4, 2001
    Las Vegas, NV
    Like mentioned, you have to consider dynamic forces. The wheels will move slightly under driving conditions. I had 275 BFG drag radials and they would rub the fender lips even though there was clearance at rest.

    I have excess room with mini tubs and 335s, but the extra room is needed to keeps things from rubbing on each other.

    Mini tubs are probably worthless without moving the springs inboard.
     
  5. Mr Sunshine

    Mr Sunshine Member

    56
    2
    Dec 12, 2016
    Missouri
    I would agree the dynamics of spirited driving would need to allow for more clearance. Probably why the 275 is the max for stock without mods. Hmm what to do? I'm ok with trimming the lip back slightly, say 1/4", but cutting most of the lip is not something I'm willing to do. Rolling may be a possibility, but the tools I've looked at just don't appear to be robust enough to get it done. And for the baseball bat method, well let's just say I'd like to see it done on someone else's car first, lol.
     
  6. Mr Sunshine

    Mr Sunshine Member

    56
    2
    Dec 12, 2016
    Missouri
    What about narrower leaf springs (2" vs 2.5") and shock relocation kits? Is this a viable option and has anyone done this or know of anyone that has?
     
  7. badazz81z28

    badazz81z28 Veteran Member

    14,029
    94
    May 4, 2001
    Las Vegas, NV
    Rolling the Lips is tough, but do-able. If I ever get my car body work done, I'm cutting them and reinforcing with a rod
     

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