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I've got a 90 Formula (L98/T5) with basically a Strano spec suspension. I run ESP. Currently I have 17x9.5s all around with 275 Kumho 710s.
I ordered a set of 4 wheel adapters from Skulte that should be here this week. I also borrowed a set of 17x11 ZR1s (36mm offset) with Hoosier 315s on them for test fitting. I've talked with Skulte and we think we have a plan for correct spacing.
Here's the rule concerning fenders in SP (15.2.A):
Fenders and bumpers may be modified for tire clearance. This
includes the portion of a hood which serves as a fender/wheel
well, where applicable. This does not permit modifications to
the chassis or bodywork inboard of the vertical plane of the hub/
wheel mounting face (at rest, with front wheels straight ahead).
Flares may be added although tires may extend beyond the
bodywork. Replacement of complete hood, flared fenders, or
quarter panels is prohibited. Plastic and rubber wheel well
splash shields may be modified for tire clearance and for installation
of fender flares as allowed herein.
So....
I know a few others have made this work. Any tips? With the 3rd gen hub being so far inboard, I'm allowed to clearance a lot.
Thanks for any tips. I'll post some pics of the test fitment later this week.
I'd like to do this as well. Looking forward to watching your progress. Good luck!
What springs/rates are you using? Is the car lowered? What are your alignment settings? I'm usually the only one in a 3rd gen at the local autocrosses. I'm usually about 2 seconds or so behind a 4th gen in ESP. They have new 315's all the way around and I have 7 year old Kumhos. Thanks, Jay
Forgot to mention that I tried test fitting my 17x11 ZR1's on the front and the wheel hit the tie-rod. I think i'm using 2.25 or even 2.5 adapters up front.
Whay would you want the 315s up frony? I find my third gens are tail happy so a thinner tire up front would even it out. I dont know much about what your doing i am just curious.
My wheel adapters came in today - 2" front, 1 1/4" rears. These bolt on to the hub and have new studs for the wheels.
I borrowed a set of 17x11 Corvette ZR1 wheels from a friend to do some test fitting. These are about the perfect width for the adapters - clears the front tierod when turning and rear control arm/inner fender clears fine on the front side of the rear wheelwell.
After (driver's side) - 17x11 w/ 315-35-17 tires. http://www.rickshank.com/firebird/Firebird315%20004.jpg
Issues to resolve while keeping it ESP legal: Vertical clearance Rear - The inner fender joins with the outer fender, and both are bent to make the lip. This will take some creativity.
Pic - http://www.rickshank.com/firebird/Firebird315%20015.jpg
I *think* that I just need to take care of the lip a bit. These tires are about the same diameter as the old ones and I've only had clearance issues under wheel hop during stupid braking. I plan to cut notches in the lip with a cutoff wheel and massage these up slightly. Front - This is a standard single sheet bent lip.
Pic - http://www.rickshank.com/firebird/Firebird315%20014.jpg
Plan - run some masking tape to make a new fender line. Cutoff wheel to cut along the sharp crease. Notch (with cutoff wheel) vertically up to the tape line that I made and use a hammer and board to try to shape a fender. Worst case, I need to buy new fenders (can't be that hard to find for a 3rd gen Firebird).
For the previous poster...details on the car:
90 Formula, L98/T5 (originally 305/T5 car).
Weightjackers in the front, 750 lb springs
Ground control sleeves out back, I believe 125 or 150 lb springs
Adjustable Panhard
Torsen T2R
Revalved bilsteins up front, std bilsteins in rear
Big bar up front (can't remember size), 1LE bar in back ( i think)
straight exhaust after SLP Y-pipe (turns down under car behind driver's seat).
It's mostly an bolt-on ESP car.
To the previous poster about balance - mine is pretty balanced with even tires all around. Its tail happy just under throttle (torque ) unless I do something stupid to unsettle the car.
I'm within a second of decently quick local ESP cars. The primary reason to look for a 17x11 315 setup is price - cheap wheels (under $600/set) and decent market for decent qualifying takeoff tires.
If you do mess up the front fenders, they should be pretty cheap. I paid ~40 each for my camaro's new, they were aftermarket ones from cap auto. The fitment was so so, but it worked out.
It's an autocross only car that gets trailered. So-so looks are almost overkill The car was repainted several years ago in a single stage white. This is definitely a 50-50 car. Looks good from 50 ft at 50mph.
Short story - AFS 36mm 17x11s on the front rub slightly on the tie-rod. When they're my wheels (not Mark's), I can fix that. So I ran the old wheels (17x9.5) on the front, with 17x11s on the back. These *can* work in the front.
I was surprised you had to do so much, uh, massaging considering that the guy I bought the car from had run 17X10s. Then I remembered he hadn't done anything to lower the car.
I have a pic of it on 17X10s ... somewhere.
Pat
__________________ '03 Lightning, daily driver, tow vehicle, 13.13@106.78 with a cold air intake | '82 Camaro Z28, ESP autocross car | Matco Tools distributor
Massage? It was more of a tickle! Yes, if the car was at stock height, it would be easier. Plus, the 9.5s are fine with it lowered. It's just that the 11s mean 1.5" more of wheel outboard of the hub.
That's not Barney. It's Blarney. It's no longer going to be referred to by that kid's TV character.
Oh and here's a pic of the car with 17X10s before I bought it:
Pat
__________________ '03 Lightning, daily driver, tow vehicle, 13.13@106.78 with a cold air intake | '82 Camaro Z28, ESP autocross car | Matco Tools distributor
How i the world, do you run 17x11s LEGALLY in ESP?
36mm offset wheels Strano stopped down for our double regional event this weekend and also said it looked pretty good.
I'm not the only one - Madarash is running something similar, but 18s in the front. With doing that, I wouldn't have needed to clearance the wheel, but it really wasn't that much material off of the fronts.
Oh, and not being afraid to use a BFH or cutoff wheel on my car. The SP rule allows you to clearance/modify fenders outside of the vertical hub plane. On a 3rd gen, that gives lots of options.
It's the SCCA Class rules allowing them that I questioned.
BTW, 36mm offset = what bs?
SP allows any sized wheel I can fit in there after allowed clearance changes. CP, on the other hand, restricts wheel width to 10" and diameter to 16" without taking the weight penalty.
Looks like backspace on a 17x11 +36mm wheel works out to 7.42".
i have a question for you rick. what was the back space on the old rims in the rear? i want to run that size tire in the rear of my car 275/40/17 but don't know what the back spacing should be. thanks.
i have a question for you rick. what was the back space on the old rims in the rear? i want to run that size tire in the rear of my car 275/40/17 but don't know what the back spacing should be. thanks.
ROH 17x9.5s from Skulte.com Negative 7mm Offset
The "diff-working" pic was the car's first event after putting in the diff the day before in my garage.
SP allows any sized wheel I can fit in there after allowed clearance changes. CP, on the other hand, restricts wheel width to 10" and diameter to 16" without taking the weight penalty.
Looks like backspace on a 17x11 +36mm wheel works out to 7.42".
My ROH 3rd gen offset Snypers measure out +/- 5" BS. Hard to measure exactly with a tire mounted.
Subtracting your 2" spacer from Skulte, from your 7.42" BS, that would put you at 5.42".
I have MAYBE 1/8" clearance between the rim (not the tire) & the tie rod. No way I could get another .42" of BS, on top of my current 5" BS.
A 18" rim might move out enough to clear the tie rod, but with only 1/2" more room, that would still be TIGHT!
I'm not seeing any way possible I could get .42" more BS. Hell, .125" would be too much!
The wheels in your pics apear to be C5 wheels, not ROH Snypers. Are they C5s?
Do the fronts stick out, past the fender lip, about 1"? If I added 3" OUTWARDS to my 9" Snypers, that is the only way I could fit 11"s up front. Even outwards, I'd have them sticking out 2". My tires sit in MAYBE 1/4". Even adding 1/4" to the backspacing, they'd hit the tie rod. They'd probably hit with only 1/8".
My wheels/tires stick out past all 4 fenders. That's probably where we are getting crossed up. I cut the fender above the wheel so that I wouldn't rub that under hard braking or cornering. Without cutting fenders, I don't think 11s are possible, especially on a lowered car.
My wheels/tires stick out past all 4 fenders. That's probably where we are getting crossed up. I cut the fender above the wheel so that I wouldn't rub that under hard braking or cornering. Without cutting fenders, I don't think 11s are possible, especially on a lowered car.
Stick out how much past the STOCK fender line? If I widened my Snypers to 11", you'd see 2.5" to the full 3" sticking out, in the front. Maybe 2" to 2.5" out in the back.
I was thinking, my 9" Snypers are really 9.5", but the ROH website lists them as 9".
In using the 11's on the rear what would be the widest tires you would recommend without having to roll the fender? I am thinking about getting this same size wheel, and I LOVE the look of the 315s, but dont want to get into the bodywork at this time.
i use 2" adapters for front wheels and have c5 wagon wheels with 275 wide rubber up front. It barely clears the tie rod. Auto-x with adapters for a while with no issues. Currently running 4th gen bird wheels with old 265/45/16 v710's .
) unless I do something stupid to unsettle the car. 
