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  1. #1

    Default How big can I go?

    I've done a lot of searching but not got a definite answer. I'm putting 17x9 cobra R 4 bolt rims on my 84 Capri RS. How big a rear tire can I put on those rims? Also if the quad shocks need to be removed to accommodate the tires what do I do about wheel hop? I have 255/40/17 tires for the front. I just want more meat on the back without any big modification. Any help would be appreciated. Thanks in advance

  2. #2

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    I have 275/40/17 on the back of my 79 fox. It required a little bit of "persuasion."

  3. #3

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    This was wheel tire combo in the beginning. No fitment issues.

    Set of Cobra R Wheels (2) 17x8, (2) 17x9
    Tires Hankook Ventus K102 Front P225/45R-17XL
    Rear P265/40ZR-17

    17x9's had a 6 inch bs

  4. #4
    FEP Power Member Hemlock's Avatar
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    The max tire size will all depend on the back space of the rims. I have 275's on my RS on a 9.5"-17" rim. I believe the back space was 5.5. If my suspension wasn't so stiff I would be grinding and rubbing tires on every bump. I chose the back space for my rims with my original 7.5 rear end in the car and I ordered my new rims off of that measurement. I had my new 8.8 built and when I got my new rims I discovered that they stuck out a half inch more then I wanted. I am now going to be narrowing my rear end about 1" on each side and with the inner fender lip rolled I am pretty sure it will just fit in the well without rubbing issues. I have heard of a few people getting 315s in there but it took a bunch of effort and a BFH and they still have minor rubbing issues.

    Robert
    1984 RS 347 Capri, To many car parts to list, check out my car build page here for the story on my car and a full parts list/setup!:

    My RS in Action

  5. #5

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    I have 265/40/17 firestone wide ovals on my cobra r's with no issues and quads flipped. I think the bs is 5.75?

  6. #6
    FEP Power Member Ourobos's Avatar
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    285/40s with 5.96" backspacing.. No quad shocks.. Fit good.
    1986 CHP SSP Coupe

  7. #7

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    By removing the quad shocks am I going to have traction issues and is it safe? I don't want to trash the car as soon as I get it going lol. Rims are 17x9 on all 4 corners. I'd like to lower it a bit as well. The stiffer the better.

  8. #8
    FEP Member
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    23.9 MM offset of the 17x9 pony r results in a 275 / 40 tire cable of being run with no modifications other than flipping the quad shocks around if you have them. I don't have quad shock and they fit great although very close to the tail pipe on the pasenger side (just need to adjust the tail pipe a bit).

    If you wheel offset pushes the tires either direction off of that then you run a chance rubber on the inside or outside with 275s.

    Check to see if you can find the offset specs on your wheels and I can probably do some measurements to see how they would compare to the pony r setup and help understand if they would rub on my car at least.

    Hope that helps.

    Steve
    Last edited by roller4v; 12-15-2012 at 03:30 PM.
    1983 Mustang GT

  9. #9

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    ok thanks. Ill see if I can have somebody measure them and figure out an offset for me this week and ill let you know. Thanks again

  10. #10
    FEP Power Member black1980fiveoh's Avatar
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    I had to roll the fender lip, I have no quad shocks, and I had to spread the lowering springs so the tires wouldn't hit the fenders on bumps. I run 275-40-17s.
    1980 Cobra http://www.cardomain.com/ride/2364382
    11.82@115 mph - 2015 - retired due to cancer
    1981 Cobra
    reborn with a lot of new go fast parts and time to make it look pretty
    11.80 @114 mph - 2016

  11. #11

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    Lose the quad shocks, get a good aftermarket set of control arms and the car will handle much better.

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