315 R6s on all four corners

Discussion in 'Brakes, Wheels and Tires' started by cloud9, Nov 8, 2014.

  1. stunya

    stunya TMO Advanced

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    I am serious about it and thanks. Ill call them next week!
     
  2. cp85gt

    cp85gt TMO Advanced

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    Now that the ice age is over I was able to get my car into the lower garage and start getting some actual measurements. I test fit the 19 x 11 rear wheel with a 3/4" stack of washers and it fit, although probably a little tight. I'll need to add some washers to the endlink bolt to space it back as that's the tightest measurement and check again. Even though I ordered a +55 offset the backspace on these wheels measured 8 1/16" which I think is a +53 offset. 8.15" should be about the backspace for a +55 11" wheel. I don't know if there is someone at Forgestar that I can contact to verify any of this. Right now I think reducing the offset 5 to 6 mm should be enough to clear in the front with the 15mm H&R spacer while poking out in the back about 1/4". SO a +47/+48 offset might be the requirement for a rotatable 11" wheel set-up.
     
  3. cp85gt

    cp85gt TMO Advanced

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    After contacting Paul at Howey Industries about my offset discrepancy I verified that I definitely have a +53 offset for my 11" wheels despite ordering a +55 offset, which is annoying. Doing some more reading on the good/bad of using spacers I found that H&R makes a 20mm hubcentric spacer which would fit the +53 backspace in the front. That's a little more than 25/32" , about 3/16" larger compared to the 15mm, and would eliminate most of the tire poke in the rear. Being that I would use these with the ARP studs in the Ford Racing hub kit, am I nuts for running a spacer that large, even an H&R, for a track wheel set-up? From everything I've read the hubcentric design does take the strain/shear load off of the studs but there are those that would never run a spacer citing stories of wheel stud breakage. I know that DGRacing is running a 1/2" spacer in front with a car that I'm sure is seeing far more cornering and braking forces than my car will, but this spacer is a little more than 1/4" bigger.
     
  4. ls110

    ls110 John

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    That is bummer that the offset is wrong. I have the same concern with my 11" Forgestars as Vorshlag is convinced they should fit yet I am forced to use a spacer. In my case thankfully the spacer is only 8mm.
     
  5. Mad Hatter

    Mad Hatter Gotta go Faster

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    Am about to help a friend get a set of Forgestar F14 19x11 rear wheels. I saw the Offset is supposed to be +56mm according to the Americanmuscle website. Nice to see they have them in stock, no two month wait. Sounds to good to be true!
     
  6. cp85gt

    cp85gt TMO Advanced

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    I got my new hubs on with the ARP bolts so I re-did my initial test fit of my 19 x 11 rear wheels (+53, about 8.09" backspace). I put together a group of washers that measured out to .790" which is about 20mm. I have about 7mm from the wheel lip to the strut, which is about half of the 19 x 10 wheel strut clearance. The backspace on the front wheels is about 7 1/16" plus the .065 spacer I use gives me about a 27mm spacing difference, so I think my math and measurements are close enough (20mm washers + 7mm less clearance). As an aside it appears my front wheels are close to a +40 and not the +42 I ordered, so consistent with the 2mm offset difference with the rear wheels. For those of you, Neema, Cloud9, LS110 running a wide set-up in the front, how much strut clearance do you have? I have seen pictures of a 305 35 18 NT01 mounted on an 11" wheel and the sidewall does curve out a bit so I don't think I can run more offset. How does a 305 Conti or Pirelli tire compare to the NT01's in terms of sidewall flex? I can see a 315 Hoosier bulging out enough on an 11" wheel that the 7mm of clearance would probably not be enough.

    If you guys running the F14 11" wheels with the different offsets front to rear really need 8 to 10 mm spacers to clear the wider Hoosiers, then those rims must be really close to the strut, like only 2mm or so, which seems a bit tight for any tire bigger than a 295. By my calculations that would mean an offset around a +38 for those 11" wheels
    (+53 - 20mm = 33mm + 5mm less offset= +38 offset)
     
  7. ls110

    ls110 John

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    With front 11" F14s, 315 Conti's, and 8mm spacers I have about 3/8' clearance to the strut.
     
  8. cp85gt

    cp85gt TMO Advanced

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    LS110, you only had about 1/16" of clearance to the strut then. Seems to jibe with my measurements. That offset seems like not nearly enough for any tire other than a stretched one, like a 285 or 295.
     
  9. ls110

    ls110 John

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    My mistake on stating I was using Conti's. I forgot they are not available in 315s and I switched to Pirellis 315/675/18. The Pirellis has 3/8" clearance from the strut, the wheel even more clearance. I have also recently mounted Hoosier R7s and found them to be about 3/8" as well.
     
  10. cp85gt

    cp85gt TMO Advanced

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    My AST 4150's are about .2" larger in diameter than the OEM struts at the area where the rim is close (2.2" vs 2") and then only .020" larger at the threaded section . So if you have stock type struts you would have an extra .1" of clearance, or almost 3mm. That might account for having a little extra wheel clearance than the 3/8" tire clearance if you are using a stock type strut. So I guess a +53 wheel would work with a 20mm spacer or a +48 with the 15mm one. I could back off the offset a mm or 2 to be safe if I wanted to try out a set of Conti or Pirelli scrubs over the NT01's. Run the spacer and rotate the wheels, use different offsets and don't rotate, or run a smaller wheel. Tough choice. I think I might need some peer pressure to make this choice. ;D
     
  11. neema

    neema TMO Race

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    Regarding clearance, you can get the wheel or tire pretty close to the strut. Everyone has their own comfort level. Typically all the deflection while cornering is near the contact patch of the tire, not near the top of the wheel. Keep in mind that Hoosiers have rim protectors, which will eat up some space. On the other hand, Continentals and NT01s do not.

    This was a prior setup without issues:

    [​IMG]


    if you haven't seen it already, check out www.wiltheyfit.com for quick visualizations comparing wheel dimensions. I use it all the time.
     
  12. cp85gt

    cp85gt TMO Advanced

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    Neema, that looks like 2 or 3 mm of clearance with those NT01's. I think that's about what I'll have with an 11" wheel as from what some have told me the 305 NT01 seem to have a bit of sidewall bulge that will eat up most of the 7mm of wheel clearance. I might back off a mm or 2 to a +51 or +52 just to play it safe.

    Thanks for everyone's input.
     
  13. patrickshelby

    patrickshelby TMO Race

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    Rehagen uses / sells 19mm (3/4) hubcentric front spacers for their BBS wheels (or else).
    I have a pair which I did not need to use yet.
    [​IMG]
    With the type of loads a racing Boss sees when braking & cornering, it must be fine to use them.
    I reckon they perform far more frequent maintenance routines and checks on parts (Hubs for example...) than "we" would do, but still...
    I feel it is safe to use their spacer.
    Reading about this topic, I am thinking if a 11"wheel with 56mm offset (which seems fine for the rear) would work on the front with a 19mm spacers which brings it to a 37mm offset...
    It should not be far. Isn't it?
     
  14. cp85gt

    cp85gt TMO Advanced

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    Those spacers look really nice , and appear to be light too. I put together a similar set-up using an H&R 20mm hubcentric spacer with a set of +55 Forgestar wheels with 305 35 18 Nitto NT01's. Have not tracked the combo yet but did some street driving and so far all is well. I have some pictures in the Forgestar 18 x 11 thread, toward the end, of the combo. You're proposed combo would move the total backspace 2mm inboard from my set-up, and with a stock type strut would work well. The 350r race cars also use a large spacer.
     
  15. cloud9

    cloud9 Gary

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    I was looking at some of the Trans Am cars at Brainerd a couple weeks ago. I saw a Boss 302S that was running two quarter inch spacers on each corner. I was running one 1/4" spacer on each corner, but I just ordered some more quarter inch spacers from Maximum Motorsports and am going to be running two of them with 315s on all four corners at Road America in a couple weeks.
     
  16. cloud9

    cloud9 Gary

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    These look really phat 8) Hoping for some added grip.

    [​IMG]

    [​IMG]
     
  17. ls110

    ls110 John

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    Those are looking very sticky!!!
     
  18. ArizonaBOSS

    ArizonaBOSS Because racecar. Moderator

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  19. steveespo

    steveespo Lord knows I'm a Voodoo Child Moderator

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    Gary
    H&R make 15mm aluminum hubcentric spacers that I think would be better than stacking two 1/4" spacers. Just something to consider.
    Steve
     

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