C5 18x9.5 rims won't fit in back

jasycZ28 · 09-04-2003, 02:48 PM

I only have 275/40/18's on them and they rub up against the bump stop deal. Does every one have this problem? Can I just remove the bump stop thing and cut out the excess wheel well? Is there a spacer sold for these? I need help fast my rear tires have no tread left on them. I need these new rims and tires on fast. Thanks in Advance.

t-trimz28 · 09-04-2003, 03:22 PM

back when I had them mounted on mine I used two 3/8" spacers, but you will need longer wheel studs.

Injuneer · 09-04-2003, 03:34 PM

Some C5 wheels have a 65mm offset, which is excessive, and provides too much backspace, putting the back of the wheel/tire into the inner fender. The solution should be similar to the way many of us have handled the installation of the 17x11 GS offset ZR1 wheels: 1) cut corner off jounce bumper; 2) hammer inside of inner fender; 3) recenter body over axle with adjustable panhard rod.

The problem with the 65mm offset 18x9.5 is that the outer edge of the wheel remains deep in the wheel well, and doesn't have the visual impact of a correctly spaced 9.5" wide wheel. You can use "spacers" but I just don't like them on a high performance application.

jasycZ28 · 09-04-2003, 06:52 PM

What size spacers would you suggest? And where can I buy these spacers from? How awful would it look with the wheel wells hammered in?

jasycZ28 · 09-05-2003, 01:59 PM

Does anybody know where to buy wheel spacers from?

Injuneer · 09-05-2003, 02:14 PM

Exactly WHICH C5 rims did you get.... what year? Z06 or standard?

Are you ruling out trimming the jounce bumper bracket and hammering the inner fenders? I have pictures of both, if you need to think about it.

Do you know either the backspace or the offset? Can you just crawl under the car and estimate how much you have to move the rims away from the fender?

If you know that, we can recommend a spacer. You can buy spacers at just about any auto parts store, or in a catalog like Summit or JEG's. But for anything other than a 1/4" or 5/16" spacer, you need a very high quality piece, not the kind of thing you find in those store. There is an outfit that sells billet spacers that will work better in thicker sizes, but they are expensive. I personally don't like spacers on the back.

And, if the spacers are thick enough, you are going to need longer wheel studs as mentioned above.

Z95m6 · 09-05-2003, 02:37 PM

I have Stock silver Y2K's and they fit with just some hammering to the inner wheel wells. I just put some undercoating back on the spot and you can hardly tell. I think the rims get close to the bump stops when the car is jacked up and the rear is hanging down, but when the car is on the ground they aren't even close to hitting.

jasycZ28 · 09-05-2003, 02:53 PM

Quote:

Originally posted by Injuneer
Are you ruling out trimming the jounce bumper bracket and hammering the inner fenders? I have pictures of both, if you need to think about it.

Do you know either the backspace or the offset? Can you just crawl under the car and estimate how much you have to move the rims away from the fender?

I am not ruling out trimming PLEASE send me pics jasycZ28@hotmail.com.

These are the thick 5 spoke rims I am unsure of year. I got them off of ebay.

I don't know the backspace or the offset. The rim won't even go on the top studs because it is hitting the wheel well. If I removed the the jounce bumper bracket what effect would that have on the car. Could the wheel well hit the rear end if I don't trim it enough?

Injuneer · 09-05-2003, 03:11 PM

Are you actually hitting the inner fender before the wheel bottoms out on the hub? It isn't unusual for the inner diameter of the wheel to be slightly smaller than the hub diameter, and interfere with mouinting. The rear hub is 0.03" larger than the front hub, requiring on some wheels that you lightly sand the inside diameter of the wheel. Just making sure that isn't your problem.

You don't totally remove the jounce bumper bracket, you just grind off the corner that sticks out and catches on the wheel (only at "full drop", when jacked, not at normal ride height).

Grind corner off jounce bumper bracket

How much hammering you need to do to the inner fender has a huge variation from car to car. Some people have no problem putting 17x11 GS offset ZR1 wheels in the back. I had to hammer a lot.... but when you get done you spray it with rubberized undercoating and you hardly notice it was hammered.

Hammer inner fenders

Inside clearances on left and right side:

Drivers side

Passenger side

C5 wheel offsets, from VETTE magazine:

YEAR-----------SIZE----------------OFFSET
STYLE------DIAM---WIDTH-----REPRO------GM
Z06----------18-------10.5--------58---------58
-------------18--------9.5--------61
-------------17--------9.5--------54----------54
-------------17--------8.5--------56

01-02-------18---------9.5--------65----------65
-------------17--------8.5--------56-----------58

00------------18-------10.5--------58
--------------18--------9.5---------65----------65
--------------17-------9.5---------56
--------------17-------8.5---------56----------58

97-99--------18--------9.5---------61----------61
--------------17--------8.5--------56----------56

jasycZ28 · 09-05-2003, 04:32 PM

Injuneer Thanks alot! By the way what did you use to grind the jounce bumper bracket? What size tire are you running?

Seanndogg · 09-05-2003, 04:52 PM

I am going with this wheels set up soon. I have heard that it is better to buy the 275 35 18's if you can. Is that true?

Injuneer · 09-05-2003, 04:55 PM

Quote:

Originally posted by jasycZ28
Injuneer Thanks alot! By the way what did you use to grind the jounce bumper bracket? What size tire are you running?

I have an air powered die grinder. It would take forever with a Dremel.

That is an AFS polished ZR1 replica 17x11 GS offset, with a BFG Drag Radial 315/35-17

SiDeWaYZz28 · 09-05-2003, 05:28 PM

i run 275/35 and my offset is 56mm and i have no problems with rubbing . . .the c5 make your car look real good

jasycZ28 · 09-05-2003, 11:12 PM

Injuneer would my tire size make that much of a difference?

fireman · 09-06-2003, 12:04 AM

I have the '98 18x9.5 C5 wheels on the back of my car. I cut about 3/4-1" of the jounce spacer(metal and all), I did it with my Dremel and it took a long time. I also beat the inner fender in a few places. I tried a spacer and the lug nut would only grab a few threads. I think the studs would have to be changed.