Hey folks,

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.

~Ricky Shank

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.

What kinda bs did you go with to fit 11s up front?

Here's the update so far....

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.

Before (passenger side) - 17x9.5 w/ 275-40-17 tires.
http://www.rickshank.com/firebird/Firebird315%20003.jpg

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).

Turning clearance
This is already notched by the previous owner. I think I'm mostly fine here. It does rub at full lock, so I'll need to make a note to "don't do that, stupid".
Pics - http://www.rickshank.com/firebird/Firebird315%20012.jpg
http://www.rickshank.com/firebird/Firebird315%20022.jpg

Rest of pics - http://www.rickshank.com/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.

Spacers+tires+wheels=1 set of new 275 Hoosiers.

-Ricky

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.

More updates.

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.

Marking up the fender with pinstripe:
http://www.rickshank.com/firebird/Firebird315a%20001.jpg
http://www.rickshank.com/firebird/Firebird315a%20002.jpg

Cut up:
http://www.rickshank.com/firebird/Firebird315a%20003.jpg

Cut up fender liner:
http://www.rickshank.com/firebird/Firebird315a%20006.jpg

Beating in the rear lips (first slotted laterally, then beat with a hammer/board):
http://www.rickshank.com/firebird/Firebird315a%20011.jpg

New rear opening:
http://www.rickshank.com/firebird/Firebird315a%20012.jpg

Skulte 2" Wheel Adapters:
http://www.rickshank.com/firebird/Firebird315a%20013.jpg

Event day - 275 fronts, 315 rears:
http://www.rickshank.com/firebird/autocross5.jpg
http://www.rickshank.com/firebird/autocross7.jpg

I think I did a half decent job with a cutoff wheel for once...

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

You bought Barney? You suck!

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

sweet ride dude im thinkin about some black 17x9.5 06 zo6 wheels for mine with 275's all around. street rubber though.....

First "real" dry event since the wheels.

Picture

Only rub was during full lock in the middle of a spin

From 10 feet, the fenders look pretty good, in my opinion of course.

Now to figure out why it won't idle in grid or hold a constant no-load RPM. After coming off the course, however, it seems fine for a while.

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 not the physical fitment I had in question.

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".

Just reviewed the Pro Solo rule book....

I was surprised to see that it is so clearly spelled out, that those are legal.

Yes, "if it isn't specified as legal, it isn't legal" is a good rule for SCCA, I was just surprised it was so clear.


Hmmmm.....

So just to get this straight, you cut away the factory flares, and added your own flares?

No flares.

Cut out part of factory flare on the front fender, along with part of the inner liner. Re-attached inner liner to car with lots of zip ties.

Rear is just "rolled" - slotted the lip and pounded it up inside.

I like the picture labeled "diff working".

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.

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 wheel clearance that I cut out was very minor.

I'm not sure which ROHs I have. Maybe the Snyper? My car is lowered with a decent bit of camber. Any chance that hurts/helps things?

For now, the car is parked and I'm trying to finish the EP CRX.

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".

The 17x9.5s I had on it before (with 275s) were ROHs. The 11s are AFS ZR-1 replicas.

I'm just trying to figure out your backspacing....

I'm at 5", and even 1/4" & I would hit the tie rod. 1" out & I would be out past the fenders....See why 11" up front isn't making sense to me?

I'm more interested in getting my rear 2 Snypers widened 2" (found a local shop!), but 11" fronts REALLY have me scratching my head...

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".

I think mine are out maybe 1-1.5" past the stock fender line.

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.


PDG

My wheels stick out past the fender. Not sure what tire wouldn't as well.

17x9.5 ZR1s with Skulte spacers would work...

btt

Have you managed to go autocrossing yet? I'm wondering if the adapters have held up. They are a concern for me.

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 .

Hi Dennis Here in Cali...
I have a 87 third gen lowered at 14" from spindle to fender lip.
Wanting to go to 17"X 9.5"? I think...lol
I have coilovers in the front, the springs are 2.5 " so they dont stick out past the strut very much at all.
I've been trying to avoid buying any rims that require spacers?
What happns to your SAI? (Steering axis inclination).
Looking at 275/40zr/17s?.Currently running 225/50R/15's, looking for a bit more grip?
Im have sunframe connectors, running approx 6 degrees caster CC plates, strut bar, steering bar, tubed aframes, etc. etc.
Can you ponit me anywhere?
Would love to find lightweight magnesium wheels that are 17"s with no spacers? Custom wheels?
TXS
Dennis

What rims are being shown? anyone know

Not sure but 'd really like to know as well, they look pretty damn good from what I can see.