Summerfun

I read too many things

Writing it down so I can try to figure out what the heck is going on inside my head.

From what I understand:
Stock C3 wheels have a 4" backspacing...front and back
ALL (not just C3)Corvette wheels have a 4 3/4" or 120.6mm bolt pattern

This means you can fit C4 and even C5 wheels onto a C3 if you make sure that your new wheels clear the 4" backspacing

So if you have a 10" wheel with a zero offset, meaning that you have a 5" backspacing on the new wheel......you need a 1" spacer.

What I don't know is whether the stock c3 wheels had a zero offset or not.

I want an aftermarket wheel to fit in such way that the outside edge of the wheel is at or just past the fender. I also want to maximise traction so I want to use all available space that I can.

What is the distance on a C3 from the outside edge of the hub to the outside edge of the fenders. Are the fronts and rears the same?

Then if for example the wheel offset changes to the positive on a custom wheel you're looking at you have to add that same amount to the spacer if you have a 4" centerline and vice versa to make sure that you can clear the 4" backspacing

No wonder I have myself confused

In your guys experience what are the sweet spot for width of wheels to fit on a C3 so I can get the widest tires on there without rubbing anything.

Offset can be set off with spacers if positive. If the offset is too much negative on a custom wheel then I presume the tires will stick out past the fender too far.

I think I understand better now

flyeri

Not exactly. Read this link. http://http://www.chevellestuff.com/...eel_offset.htm

A 10" wheel with zero offset will have a 5.5 inch backspace. A 15" wheel will need to be no more than 4" backspace. With an 18" wheel you can go with more backspace allowng a wider tire. I don't know how much without moving the parking brake bracket but someone here can tell you. I have 17" x 8" wheel with 4.1" backspace and everything else stock. 255/50-17 tires in the rear, 245/45-17 front, no rubbing anywhere.

3JsVette

WOW! Lots of questions. Lets start narrowing things down. What do you want to do? Are you looking at 15s, 17s, 18s, staggered fit 17s and 18s? What year C3? Do you want to be able to rotate the tires? Remember these cars are not all the same. What works on one might not on another. Try to work with backspace as it's easier to answer the questions. As stated above a 10" wheel's backspace is 5.5". That's because a 10" wheel is really 11" wide fron edge to edge. The rim bead is about a 1/2" thick so that's where the extra 1" comes from. Someone here has probably done almost any combination that you can think of. So if you can narrow it down to what you're considering you should get the answer you're looking for.

Summerfun

I'm looking at getting an extra set of 17" wheels to do autocross with. Trying to maximise the traction. I have 1000 lbs of engine up front which I've been told drives me into understeer......I was thinking something like 180AAA 255/4017 front and 280AAA 285/40/17rear.

I would go wider in the rear if I could get it to fit in there. I may even consider staggering 17" in front and 18" in the rear.

For autox days, which is only probably 4 or 5 times a year, I'll just put this setup on the night before the event.

Before I start looking at rims, I need to try and figure out first what will work. Got my brain all confused when I started reading stuff from all over the place

3JsVette

OK. You can get more wheel under the back if you go with 18s back there. A 18x10 with a 5.5" backspace can get under the rear. The 18" hoop allows for a little bit more clearence. If you go with 17s a 17x9.5 with a 5" backspace works. I would not be dead set on the 285s though. 275s are only slightly smaller but that might be the little extra you need for no rubbing. The front a 17x8 with 4" backspace seems to work for just about everyone. You may want to go with a 245/45-17 tire though. If you go with 17s all around a 245/45 and a 275/40 are the same overall diameter.

Summerfun

Excellent, thanks for the help and info

Just to clarify....

For clearance purposes on the inside (not fitment in regards to the positioning with the fenders) I can run any wheel or wheel adapter combination as long as I have at least 5.5" backspacing on an 18" wheel or 5" backspacing on a 17" wheel.

Sounds right to me, but these things never end up being black and white

Tangelo79

I have 17"x8" front with 245/45's and 17"x9.5" rear with 4.5" backspacing and 275/40's. Clears the stock control arms (even park brake) and sits flush. I know 4.5" is a strange back spacing but it will clear stock parts...just barely

Dheista

Hi Tangelo - can you give me some insight as to what you give up and what you gain by having smaller front's than rear?

And I've looked around a bit - I'd prefer to do RWL rather than blackwalls, but if I go to 17 or 18" wheels, not sure that's a common thing? I seem to find a lot of 15" RWL tires...

Need to get some new wheels and tires on my 73. Soon!

stingraymaniac

I have 17x8 and 17x9,5 on mine also but 5,5 backspace in the back,i needed a spacer to clear the trailingarm so im at 4,5 also now.
But i have 255/50 and 225/55 tires on mine to match the original tire size
looks better with bigger wheels in the back imho

3JsVette

I don't think you're going to find any 17s or 18s with RWLs. You may want to try this.
http://www.duplicolor.com/products/hotTires/

Tangelo79

Dheista i agree with 3JsVette about the color pen for the letters not sure you will find RWL on a bigger tire. The rear wheels aren't any bigger diameter just wider for looks and better traction

Stingraymaniac i really like the look of your car! The luggage rack balances it out. My Dad and i did a frame off on a 74 for my mom. Since the wheel pics i posted i put the front D80 spoiler back on and switched to OBX racing stainless side pipes

MrJlr

Your wheels are EXACTLY what I'm looking for !
Do you have part numbers, brand, supplier info ?

eagle275

Cool! Have been looking for something like this.

roscobbc

I have 285/40/18 on 9" rims with 5" backspace - therefore has same 'track' as stock so no interferance with outer wheelarches - however it is VERY close to the inner wheelarches where the trailing arm pivot in body. There are more cars about now with 18" rubber around so theoreticaly selection should be easier and cheaper.

worship79

Stingraymaniac & roscobbc, what wheels are those??

roscobbc

mine are boyd junk yard dog.

gillonjd

It sounds right. I have 19x10 with 5.5" backspace and small mod to trailing ARM pocket to accomodate the larger OD of the 285/40 tire that is 28 inches. The 18 with 5.5 backspace will be fine with a 40 series tire.

I like staggered look and run 18x8 with 4.25 backspace on 245/45. Compliments the lines when car is raked in the front. IMHO.

stingraymaniac

Hello mine are revolution thrust but i think they are called mb old shool in the states

stingraymaniac

Nice car! I like the front spoiler,Thats something i would like to put on in the future

Tangelo79

Thank you front and rear spoilers are the factory D80 option. Your car looks great with the wheels and side pipes bet it is a rare sight and gets lots of attention in Sweden!!