Budget 18" wheels for F Street on a 2017 PP1 GT

Discussion in 'Road Course, Track, Autocross, HPDE' started by Rocwandrer, Feb 17, 2020.

  1. Rocwandrer

    Rocwandrer Member

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    I've done some searching. I'm sure the answer is here, but I didn't find it.

    I'm looking to be able to run 18" tires within F Street allowances on a 2017 PP1 GT, partly for tire cost savings and partly for more size and compound options. What are the low budget options that clear the brakes?
     
  2. BmacIL

    BmacIL Enginerd

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    Low budget? Not many at all. Apex EC-7 do. Given the constraints, I'm not sure what you'd gain doing that over a 275/35R19 RE71R on stock wheels or stock size wheels. The only wide-ish 18" size that's going to be in the diameter range you want is 265/45R18.
     
  3. strengthrehab

    strengthrehab Well-Known Member

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    Only 18's that work are
    Apex EC7 (maybe SM10)
    Forgestar
    Team Dynamics (18x10 only I think)

    I don't know FS rules, but are you allowed to change wheel diameter/width?
     
  4. BmacIL

    BmacIL Enginerd

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    Diameter +/- 1" but width must be the same.
     
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  5. OP
    OP
    Rocwandrer

    Rocwandrer Member

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    Actually, for our local courses, I think smaller diameter is better. I'm looking at 285-30/r18. My use has a mix of mid second gear courses, and mid 3rd gear courses. Both would benefit from lower gearing, and lowering the car an inch within the rules is a bonus I'll gladly take.
     
  6. BmacIL

    BmacIL Enginerd

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    Yeah only you can know if it works for you. For most I've been to, shorter than 26" would get problematic with hitting rev limiters all the time, and not enough of a wheel torque gain to offset the shift to 3rd and back. In CAM that issue is lessened, as I can rev a lot higher than the OE 7000 hard cutoff.
     
  7. SteveW

    SteveW Well-Known Member

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    If you had an EBPP or non PP GT there are budget 18x9 wheels available that would work for DS/FS but the only way I've heard of doing a GTPP in 18" is with custom Forgestars. Squeezing a 285/30-18 RE71R on a 9" wheel sounds painful, too. There is the 275/35-18 Rival S 1.5 and that's a sweet tire. I have a set that I stretch across an 11" wheel.
     
  8. Grintch

    Grintch Well-Known Member

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    Right, staggard stock wheel fitments under Stock rules make it way harder to find suitable wheels. As you have to match not only the stock width but get pretty close on offset both front and rear with the same wheel design. If only Ford would offer a stand alone square 10" wheel option.

    Personally, I think the wheel & tire selection is too thin in 18" for a GT PP in FS, I would stick with 19's.
     
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  9. Dana Pants

    Dana Pants Well-Known Member

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  10. OP
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    Rocwandrer

    Rocwandrer Member

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    So the listing for the OE FR19c 18x9 says it doesn't fit over special package brakes, but there are mentions on this forum of it fitting. Anyone here actually mount them up and find they didn't fit,r or them on a PP1 car?
     
  11. ahhter

    ahhter Active Member

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    The only real "budget" option that I've found in FS is to snag a set of cheap used OEM PP1 wheels and run 19" tires - either 285 Stones (what I run) or 275 Rivals.
     
  12. BmacIL

    BmacIL Enginerd

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    Running 275/35R19 means they're a whole inch smaller diameter than OEM PP rears, also.
     
  13. DickR

    DickR Well-Known Member

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    Richard - Be sure to keep the installed with spacers offset within the permitted FS limits of +/- 7.00 mm from the stock GTPP1 offsets of 45 mm F and 52.5 mm R.

    Also do you have any data logging to verify that you actually use full throttle in those low speed/rpm sections in second gear? Also how much "on the limiter" time in second? Usually it is faster to sit on the limiter in 2nd for a second or two (per logging . . . not "it seems like forever when driving" :-) ) rather than upshifting and then downshifting almost immediately. If you do have long sections of 3rd gear are they full throttle at speed higher than the rev limiter speed in 2nd?

    If not full throttle or if you still need to shift up or down very soon then shorter gearing may not help. Upshifts take a lot longer than most of us think. Assume most 2 -3 upshifts with a stock shifter are over 1/2 second from throttle lift to full throttle again IF you are really fast. Then add the braking complication at the next corner if a downshift is included. Also note that given how rapidly our engines rev in second you will probably short shift simply to avoid hitting the limiter and/or due to needing the course to be straight enough to shift.

    At least FS cars actually accelerate in 3rd gear vs the small engine cars which ride the rev limiter a lot since they don't accelerate "much" in third gear anyway. :-)

    FYI I ran a 2015 GT PP for 3 seasons and fully understand your "pain". My 18 GTPP1 10 speed never has a gearing issue . . . if I don't hit a paddle at the wrong time. :-)
     
  14. mikeD4V

    mikeD4V Well-Known Member

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  15. kz

    kz Well-Known Member

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    You are missing "for F Street piece". They have to be same width as OEM wheels on the car (so 9" front, 9.5" rear) with offset being +/- 7mm from OEM.

    OP - compound meaning A052s ?

    Low cost wise I have 2 sets of Axis model 5 wheels I bought from Tire Rack - they were 19" though, ET45mm front and ET 47.5mm rear (with correct widths) but they are long gone now. They were $250ish per wheel initially, much much cheaper when being on closeout (I think I paid $90/wheels for last two rear ones - which is how I ended up with two sets). Might be selling them at some point.
     
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