hey folks.

I have admired the ZL1 Camaro for a while and I know that they have an 18 X 12.5 inch rim on the rear and 18* 10 on the front. They are a Fiske wheel and they flared the rear fenders.

I'm thinking of doing the same but can anyone let me know the backspacing and offsets that they think they would have?

TY

 

REAR
FISKE 10" x 18" (#851585) with neg. 2" offset
GOODYEAR EAGLE F-1 FIORANO P-335/30 ZR-18

FRONT
FISKE 12.5’ x 18 (#854580) with neg. 3/16" offset
GOODYEAR EAGLE F-1 FIORANO P-265/40 ZR-18

thats all i could find for you if that helps.

 

Those numbers look odd.... 10's with 335 in the rear and 12.5's with 265's in the front????? I know that's from the ZLX website, but there are numerous errors in the data they present for that car. I wouldn't trust the numbers. If they managed to mix up the wheels sizes front to rear, who knows if they have the offsets in the correct spots?

In the back, the absolute largest backspace you can fit on a stock axle spacing with stock inner fenders is 8.00".... and that's a stretch... 17x11 ZR1's with 7.93" BS seem to rub on some cars.

That said, I think in the back you want a 18x12.5 wheel, with a 30mm (1-3/16") offset, giving you about a 7.93" backspace. That would give you a 5.57" "frontspace", meaning you would have to flare the fenders about 1.5" just to have them barely cover the tops of the tires (same as the 17x11 50mm ZR1 looks). Appears what they really meant to type for the REAR: was

18x12.5" 1-3/16" neg offset

In the front, you can live with about a 7.4" backspace, before the inner edge of the rim gets too close to the steering knuckle. That's with a 17" wheel.... an 18" wheel would move the edge of the rim uip 1/2" along a part of the knuckle that is bending away from the wheel, so lets say an 18" wheel could get away with a 7.5" BS, assuming no mods to the steering knuckle, and that the LS1 knuckle profile is similar to the LT1 knuckle, even though they are slightly different.

So... a 10" wide wheel with a 50.8mm (2.0") offset would give you exactly that 7.50" backspace. And, the "frontspace" would be 3.50", which is about the same as a Torque Thrust II 9.5" wide wheel.... so a fender flare would not be absolutely necessary, assuming you like the aggressive look of the TT II. Appears thye got the 18x10 2" neg offset right... they just put it on the wrong end of the car

ZXR - ZL1 website

 

TY for the help

So let me ask, why have more people not flared the fenders for bigger wheels? It does not look that it would be THAT big a deal. I saw the ZL1 a few years ago and those bulging fenders really look fabuloue to me.

I notice the ZL1 car had to "rework" the control arms. Not sure what that means if you had the right backspacing?

 

I've had the very same thoughts going through my head for a while now. It seems that to fit 12"+ wide rims on the back of our cars would take a lot of modifications, a big f'in hammer will not cut it. You will either need to take the fenders off and have alot of body work done, or mini tub it with alot of suspension mods. On verts the pump to raise the top is in the driver side rear fender, that would have to be relocated. To make it work and look the best you would need to do a little of both, mini tub and body work. Then you could run 13"wide rims and 345 wide drag radials.

Personally I have given up on this idea, and have just settled for Iforged rims (18"x9.5" front and 18"x11" rear) and 315/30/18 drag radials...........that should be big enough!

With a 5lb sledge I think I can make it work!

 

Well I'm not going to mini tub I know that and I have the 11 inch ZR1 wheels now so the "hammer" modifications have been made already. I have Hotchkis control arms and was wondering what "modifications" to the control arms means in the website above.

I don't mind getting the fender lip cut out and re-worked for another 1.5 inches of clearance though. Isn't that all I need to do?

Anyone else got any thoughts. As I say, it surprises me that others have not already gone this route but also worries me as a result.

 

Injuneer

So what are the exact specs I need to give to a wheel maker?

Front 18* 10 - 7.50 inch backspace and 2 inch offset.

Rear 18 * 12.5 - 7.90 inch backspace and 1 3/16 negative offset.

That sound right.

I then need to flare the fenders by about 1.5 inch to accomodate? If I custom order these I have to get the dimensions right.

 

Can anyone confirm these wheel dimensions? Injuneer?

 

my wheels are all 18x10 with a 7 1/4 in BS. and in the front they are exactly flush. AR lists a 1/4 BS for every 1/2 in width. so if you could get a 7 3/4 in BS like the 17x11 have ,you would only need to flare about 1 1/2 inches.

 

Hmmmm
I called Fiske and they gave me the following for the part numbers listed on the ZL1 website.

Front

51mm Positive Offset 7.375 Back space,

Rear

6.3mm Positive Offset 6.875 BS.

Now I have no idea WHAT to think.

Cost is $4500 USD..

Might need to find a cheaper alternative or give up on this line of thought.