3.1EyeCandy

iTrader: (3)

So I"m looking to get a set of custom wheels, probably in the 17" or 18" sizes. I've got a 1987 GTA with the 9 bolt rear end and the stock GTA wheels on it. What kind of sizes/offsets should I be looking at? Are there any differences between the 9 bolt and the 10 bolt thirdgen rears as far as affecting new wheels?

Honestly I'm really new to all this and it's a bit confusing. Go easy on me.

Thanks!

3.1EyeCandy

iTrader: (3)

bump ^^^ I know lots of people end up asking questions like this and it would be great if we had some kind of sticky post or something for it.

In fact, if you guys wanted to post a pic of what you're running, the specs, and what your Camaro/Firebird is equipped with - that would be fantastic.

CrazyHawaiian

The wheels specs will be the same between 10 bolt and 9 bolt rearends.

When I want to determine fitment I usually decide on the widths of the wheels front/rear first. I do it like this because the backspacing/offset specs are based off the width. So once I've decided on the widths I want I try to determine the correct backspacing/offset. There are a few ways to do this, one way is to go by what others have already done but be sure to do research. Since these specs are not based on diameter there is alot of known good width/backspacing combos on these forums. So it disnt matter if its 15" or 18" wheels, if they're both the same width then they both need the same backspacing/offset to fit. But another thing to keep in mind, there is no single backspacing/offset answer for each width. Our cars can fit a range of backspacing specs depending on ride height and tire size so you might see a range of combos people are using with the same widths. Just remember that getting the wheels to fit and having them look the way you want are two different things. Some people like wheels flush with the fender lip, others like wheels more inset to the chassis. Some people dont mind a little contact, others do. Another way to determine fitment is to make your own calculations. The best source of info I've found on this is Andris Skulte's Wheel Adapter FAQ. That website will show you how to calculate these specs off your car to determine perfect fitment. Once you've got the wheel specs down, then you need to decide on tires. Tire choice is important because it affects the overall height of the wheel and tire combo. Be sure to compare the tire heights you're looking at with the OEM tire heights and know what effects this will have. Ride height and personal preferance as far as looks can play into your tire choice. Tire calculators can really help with choosing tires, you can find them by searching on google.

3.1EyeCandy

iTrader: (3)

Thanks CrazyHawaiian! I agree with you about the stickies - I've searched a couple hours worth and scoured the FAQ board. This is a topic that everybody wants help with but there are no definitive threads. Thanks again!

Thunderfest

I will try and relist some of the info that was delete to help explain why brake choice matters. If you could please edit your post with what brakes you have on your car with those wheel specs so everyone can know how they set if they have different brake mount surface offset I am relisting below.

Standard Non-1LE front -small bearings(10.5" rotor)
3.630"

1LE brake setup- large bearings (12" rotor)
*THIS IS THE FACTORY STANDARD FOR 245/50-16 tires on an 8"wide rim*
3.948" [+.318 offset, or just over 5/16"]

Custom Wilwood setup (RTFC)-large bearings alum hub (12.9" rotor) with a 3/16" wheel spacer for rim to caliper clearence
3.967" [+ .337" offset, or just over 5/16"}

13" C4 HD's on 1LE hub-large bearings(13" rotor)
4.248" [+.618" offset, or just shy of 5/8"]

13" C4 HD's on std hub-small bearings(13"rotor)
3.930" [+.300" offset, or just shy of 5/16"]


You can now see how a senerio like going from standard brakes to C4HD w/1LE hubs can change the backspacing by just over 1/2". Could mean the difference of someone using a 4.75bs front or a 5.25bs front on the same width rim.

part 2
Diameter does not change offset, width does.

So with the above figures on those perticular brake mounting surfaces and 8" wide rims, you should be able to simply add the width of the rim to the backside and subtract half the new rim width difference to the offset to match the same outer tire edge overall.

example- 8" to a 9" is 1 inch difference on the inner wall of the rim so half that difference is .5" or 13mm. Since the new rim is wider, the center line of the rim changes so a new offset calculation is needed.

We now start with a 9"rim that has a centerline (o offset) +.5" or +13mm inward from the 8" rim. Subtract the difference.
+5mm subtract +13mm = -8mm offset

So a 9" rim on Standard brakes would need a -8mm offset for maximum turning radius clearance without hitting the fender in suspension travel.

From what I have measured on my car and being so lowered, I would never go larger than a 9" wide rim and a 10.2" tire up front.

Shagwell

diameter DOES play a difference in back space. A larger diameter wheel will allow you to run a greater back space on our cars due to the angle of the strut and the buldge in the middle of the rear wheel well.

- I'll post my specs and pics again if anyone wants

Thunderfest

if you are haveing that problem on the front rubbing the strut then 1 or both of to points

1) you are running the wrong offset

2) you are running too wide a rim

My specs are dead on accurate for a properly sized 25.7" tall tire and 10.2" max wide no matter what size the rim width and diameter. The only proper way to lower a car AND put wider tires onto it WITHOUT fender well modification is to run the offset I listed above and not go larger than a 9" rim and a 10.2" tire. you can go wider if you choose, but you will factually suffer in turn radius.

Also everyone please note that 16's and some 17's will not clear the tierodds if using a wider rim. taller and more outward protruding rims and tires may be fine on a stock height car, but not a sufficiantly lowered one. If anyone is getting to were they need a larger diameter rtrim to clear the tierod and/or the strut- then you are going to rub the inner fenderwell when turning the wheel towards lock. At this point, modification is needed.

And Shagwell, I've seen the few pictures you have already posted of your car- nice car by the way- but its not lowered all that much and your specs are not needed because I can see in your pictures that the rears stick out to the fender lip edge and would hit the fenders if the car was lowered enough and you encountered a bump.- you would do damage. At your ride height and your bmpstops, its appears that it is working for you from what you state and thats great for you. Just want others to understrand how it can be fine at one height, but not lower.

Thunderfest

Wouldnn't be right of me to mention someone elses car not being low if they haven't seen my for comparison. Since your're new around here Shagwell, here's a lowered car that will not ground out under the harshest conditions, noir will it hit the fenders. Its even seen the high bank on California speedway with bank compression and two 250lb occupants @ 123mph.

This is what I mean by tucked. the suspension movement further allows the tire to move upward into the fender without contact through suspension travel.

And If you look closely- those are 16" factory IROC rims with 6piston 13" custom made Wilwood binders on billet aluminum hubs.

CrazyHawaiian

I think it would be usefull to come up with a chart of different widths and backspacing/offset specs front/rear tire sizes, maybe even ride height.

I'll throw some out that I've tried:

8" wide front w/ 4.5" backspacing 245/40/18
8.5" wide front w/ 4.5" backspacing -7mm offset 255/45/17
8" wide front w/ 4.35" backspacing 245/50/16
9.5" wide rear w/ 5.5" backspacing 275/35/18
9.5" wide rear w/ 5.47" backspacing +5mm offset 275/40/17
8" wide rear w/ 5" backspacing +16mm offset 245/50/16

And I know I've read of others running:

8" wide front w/ 4.75" backspacing 245/40/18
9.5" wide front w/ 5.5" backspacing 275/40/17
9.5" wide front w/ 5.25" Backspacing 275/40/17
10" wide rear w/ 5.75" backspacing 275/40/17

Thunderfest

part3
Now factory IROC fronts 8" wide are 0mm offset and rears are -16mm offset.

A 8" wide 0mm offset rim can be spaced out as far as .525" safely without the tire coming into contact with the fender on a standard 10.5" factory brake setup. you can go further if you choose, but any more just be warned that the tire will contact the fender if the car compresses to low. Its your option, I am just stating helpful info

So in laymans terms-
Max outer offset of a 8" wide rim on standard brakes is +13mm.
So if factory fronts are 0mm, you have a range of 0mm to +13mm offset on an 8" wide rim. I have gone as far inward as -11mm with very slight acceptable rubbing at full lock where I back off just slightly and still have a very good turning radius. This range from +13mm to -11mm with an 8" rim is equivilent to the inside edge of a 9" rim that is 1 inch wider of course (or 1.000) I was replicating a .944" wider rim than the 8" when I was slightly rubbing. So another 1/2" to a 9.5" rim will really restrict your turning radius while remaining the outer edges ability to tuck.

Max offset of 1LE brakes is +5mm on an 8" wide rim

Now these spec are the outer most edge of the tire clearing the fender still. With the outer edge sitting here, the widest rim you can get going inward from this vertical line is a 9" rim with very minimal and acceptible rubbing slightly on the inner fender well (frame area) at full lock left or right with a 10.2" tire width which is about normal tire width for that size rim.

So now you want to jump up to a 9" wide front rim?
Then the offsets change due to rim width and centerline changes.
Specs for 9" wide front rims on standard brakes is 0mm offset.
Specs for a 9" rim on 1LE brakes is -8mm offset.

Now if keeping the tires ability to tuck into the fender properly is not a concern for you, then skies the limit. Anything sitting outermost then these specs will hit the fender it the suspension compresses enough so it you want to run a 9.5, then you can also run a 20" wide rim. There is no limit once beyond this vertical barrier. Its your choice, you are armed with the facts.

Dean

Thunderfest

There are plenty of people on this board running lower than this guy and that rim offset will definately hit the fender if that car is lowered any more than the inch it is or even if he gets passengers in the back seat on hits a substantial bump.

3.1EyeCandy

iTrader: (3)

Thanks for all the info guys. That chart Crazy is exactly what I was looking for. I wish everyone could be more civil about it.

As far as how this pertains to me - I'm looking at a set of 17" wheels - preferably 17 * 8 in the front and 17 * 9.5 in the rear. I'm open to suggestions though. I don't plan on dropping the car initially - the stock springs sag enough. But in time that will come as well. As far as how far the wheel needs to be - I like the stock position, and not want to run the risk of having a tire hit a fender. If the wheel can be pushed out a bit and not have that problem - that'd be great.

What are your specs again Crazy? I told you long ago I'd copy your wheels one day

CrazyHawaiian

Here's some pics of my cars and different setups I've run:

ROH ZS on Eibach Sportline Springs - No rubbing except on the freeway at higher speeds hitting a good dip, stupid rear springs would almost bottom out (had alot to do w/ rear shocks too). But nothing as far as normal driving.
8.5" wide front w/ 4.5" backspacing -7mm offset 255/45/17
9.5" wide rear w/ 5.47" backspacing +5mm offset 275/40/17



And here are the same wheels on my IROC-Z lowered well below Eibach Sportline ride height. For this IROC-Z I did not care about maintaining OEM height so I went shorter than stock tire height to give more clearance at a lower ride height. 235/40/17 front tire. While this does not really have much to do with the wheel spec, this is an example of the tire choice affecting fitment. I have no rubbing at all but I do plan to modify this setup to try and get more steering angle



Here are my Boyds, first two pictures is with Sportline springs in the front but weight jacks w/ custom spring in the rear. I had no rubbing problems with this setup. Last picture is the current suspension setup which I would consider extremely low. I still do not have any rubbing problems at this ride height. I would not want to go any wider in the front at this ride height, but its entirely possible to raise the ride height and run wider wheels. I am limited because of my ride height, not the car itself.
18x8" front w/ 4.5" backspacing 245/40/18
18x9.5" rear w/ 5.5" backspacing 275/35/18

Thunderfest

{Info edited and consoledated in upper posts.}

CrazyHawaiian

So .. here's some pictures of other members cars with aftermarket wheels and what specs they used, maybe even other info they posted regarding fitment.

Here is ChevyKen's car:
17x9.5 front w/ 5.25" backspacing 275/40/17
17x9.5 rear w/ 5.5" backspacing 275/40/17
According to ChevyKen his car looked like it would have tie-rod contact at full lock with 5.5" backspacing in the front so he went 5.25". He said he still has minor rubbing at full lock, same ammount he had with stock 16's (full lock in reverse). Spring setup is Jamex springs, advertised 1.5" drop...


Here is Rocc4u's car:
17x9.5 front w/ 5.5" backspacing 275/40/17
17x9.5 rear w/ 5.5" backspacing 275/40/17
According to Rocc4u the car has no rubbing problems. He is running Hotchkis springs, advertised 1" drop. Now I've heard of other people running this same specs having minor rub at full lock, all depends on the ride height.


Here is 17x9.5's on all corners on Dan Burk's bird, These are the ROH ZS wheels, as far as I know they only come in one spec for the 17x9.5. Its 5.47" backspacing 5mm offset. I think he runs WS6 springs, not aftermarket. I dunno about rubbing or contact but I highly doubt it.


Here is JohnyIROC's rear setup, 17x10 w/ 5.75" backspacing and 275/40/17 tires. Unsure on contact issues but I think he is running weight jacks and custom spec springs like me (aka adjustable ride height):


JeffW's car:
17x8 w/ 4.5" backspacing and 275/45/17 tire
17x10 w/ 5.75" backspacing and 285/40/17 tire
JeffW is running sportlines but I'm not sure if there is any contact or rubbing. If there is he dosnt mention it.


There are alot more members we could look at too. 18inchboyds, Kandied91Z (has alot of experience with alot of different backspacing specs), Camaroguy18, and then there's the guys with 315's .. dennisbernal91z, DigitalMonarch0, Shagwell, etc ...

Shagwell

-1"???

I'm running the Eibach sportlines and the energy susp. damper things(not sure of proper name) I also have a monsterous stereo(for a vert anyway) in the trunk. My 12's weigh over 40lbs each, and there's also 2 batteries back there, along w/ two large amps, and two capacitors. The car weighs 4161 w/ me and a little under 1/2 tank. Wheels are 17x8 front(4.25 back-space) and 17x11 rear(8" back-space, 4thgen rear) 245/45 front tires, 315/35 rear. - I've now listed all my specs and want to note that even on crap-azz Orlando roads at 50+ I've never hit the lip of the wheel well, and no, it hasn't been rolled/folded any. I would hit bump stops before the tire could contact...factory, unmodded bumpstops...

also, thanks for the kind words Crazy

edit: sorry to hi-jack this thread, just listing my specs.

Thunderfest

{Info edited and consoledated in upper posts.}

3.1EyeCandy

iTrader: (3)

Shagwell - thanks for posting your specs. I'd also appreciate a picture or two if you have them.

Crazy- Thanks for your specs and your assistance on this topic. I'd like to create a large information thread/FAQ/technical article with this kind of information and I really appreciate all the help.

Keep the specs/info coming guys!

Thunderfest

I will ask people to be honest and forth coming- It is not a stab. I'll explain- Often someone buys a part for their car becomes partial to it and will preach it as the best in some cases, or say it works for them when asked but they really know the little problems they may have and do not want to look stupid for buying something wrong (which is silly- happens to all of us), or any other close senerio or reason as to why claims are made.

I will keep preaching this becase I do know chassis tech like a first language. I also have years of experience in buying the wrong parts that either did not work at first, or did work for years but problems later arrose with new mods, or the parts wore or broke easily, etc. _I share that experience. Fact is fact, no matter how many people like it- I will stated again that there is only one RIGHT way of doing it and many OTHER WAYS of doing it. What you choose is you choice, but if someone comes in to post info (Lets take this post subject of rims for example) on an offset they have on the car- BE HONEST AND TELL THE GOOD AND BAD POINTS (I capitalize this not for yelling it like I think most look at emotion, I capitalize it to emphasize its importance). I will give an example-

{My name is JohnDoe
I run 11" rims on the back with such and such offset or such and such backspacing on a standard 3rd gen axle with factory disc brakes. The tire I am using is xxx/xx/xx and the outer sidewall verticvally sets 3/4" outer the fenderlip (This is fine for me- however, word of caution for anyone else trying this the tire does stick out and will not tuck without damage. The back sidewall come 3/8" from the iiner fenderwell but does touch in hard corners only since I run a stock pandhard rod.}

Now I would think fine with this example because I have no problem with critiquing it because the guy was honest and anyone else buying 11's will know from reading his post alone that be warey in case you are low enough and need it to tuck.

Fact is fact, people will still want to put 11's on their car even knowing they do not tuck and will keep thesuspension travel high enough so they never have a problem- but realistically does this make it RIGHT? No A proper fitting tire and working suspension will tuck- A LEGAL fitting and working tire will tuck. YOU CAN ALSO GET A TICKET FOR THAT TIRE STICKING OUT TOO FAR AND SLINGING RAIN, MUD, AND GENERL ROAD DEBRIS- so it is a way to do it, but it is not right. BUT YES. PEOPLE HAVE THE RIGHT TO THEIR CHOiCE OPINIONS. DOES NOT MAKE THEM STUPID IN MY BOOK so please do not claim I think someone is wrong for doing such or stupid. Its working for them, but to the reader, it may have reprocussions and reader beware.

The RIGHT way works for everyone. And to the new guy that can't understand this stuff like many of us, thats what info they need to know and what ill affects MAY happen based on their current setup and their FUTURE mods.

This entire post has been VERY helpful to anyone reading it- people are more informed as to what questions to ask if they read this entire discussion. Good debate gets info to the hands that need it.

Thunderfest

{Info edited and consoledated in upper posts.}

CrazyHawaiian

heavy_chevy29

17X8 with 4.5bs(front)
17X10 with 5.75bs(rear)

im very happy with the way they turned out and the fit is perfect. hope this helps.



this is the rear lip. it just gives you an idea of how deep it is.

Thunderfest

HeavyChevy, That offset looks perfect for your car and brake setup- Nice car.

Thunderfest

{Info edited and consoledated in upper posts.}

3.1EyeCandy

iTrader: (3)

Now that's some good info. I hope this trend continues. Also - I read this a bit ago and found It VERY helpful:
http://www.skulte.com/adapterfaq.html

heavy_chevy29

i still have factory brakes all the way around. im looking into upgrading with ebmiller, so ill post the results when i make a decision

Thunderfest

By factory I am assuming you mean 10.5" Standard disc brakes in front and possibly drum in the rear.

Whether its disc or drum in the rear, the mounting offset of the brake drum/disc will not change on the back of the car.

All of the front options will push you out further, so just be cautious if you ever decide to lower your car.

I'll show you guys what I did on my setup so I can always maintain the outer edge of the tire to very percise specs. It cost a bit of money to do this but I have machined hubcentric wheelspacers to set a pair of factory *REARS* Iroc rims onto the front of my car.The spacers are semi press fit. I say semi because you do not need a press to force them on, but they will not come off by hand and are machined to hold center on the hub at all times (aka,hubcentric). You can see the custom spacers pictured below. They are machined also for lightness and are aluminum with a black hardcoat finish to match the aluminum Wilwood hats.

What ever choice in rims I decide to ever make in the future (if I ever change them) I can pretty much choose any offset in the range I have listed above and re-machine new hubcentric spacers if needed to get the wheel setting where I want it. I did this after I installed my brake setup knowing I will never obviously change it, but may someday change the wheels again. (Note: I run 4 IROC *rears on the car all with the same offset of -16mm so I can rotate my tires. These rims did not come factory on my car, its an RS with original 15x7 rims).

Without the spacer, my brake offset mount surface shown here is +.337 from the standard 10.5's. With the spacers (.818" thick) as shown, the mount is at +1.155" offset. I then run the IROC rear which is -.630 so I set the rear out +.188 than if I had a factory *fronts on there. This is how you percisely control your offset when not giving percise options from wheel manufacturers. I also probably have the only 3rd gen running factory 16" rims with the same front and rear offset so I can rotate without dismounting tires. CH, This stock rim guy does know what I am doing

CrazyHawaiian

Hey, I never said you didnt know what you're doing. My personal opinion someone that has run aftermarket wheels w/ custom specs can probably contribute to a thread like this more than the average joe with stock wheels. But you are very technical and your information does help alot. Here's something people can use to tie in what you're saying with the specs they might see around on the forums:

Centerline + Offset + Rim Lip = Backspacing

I know I know simple formula (copied from Andris's Website) but it should help people correlate the info you've posted with info others have posted, hopefully they can determine perfect fitment as far as both backspacing and offset (since both are important).

I've also edited my post to remove all the nonsense and instead I'm posting pics of other members cars and my own with as many specs as possible.

Gr89RS

iTrader: (5)

See, the thing we need to remember is that 3.1eyecandy likes the stock location of the wheels. Now not to take away from your car heavy_chevy, but your rear wheels stick out much farther than stock. My question is this, with a 10" rear wheel, theoretically wouldn't a 6.75" backspace be needed to tuck like stock? (Yes fender well massaging and modification would be needed with a 10" wheel.)

Thunderfest

With all due respect, I think HeavyChevy's offset is sitting perfect for 10" wide rears. the tire edge is vertically still under the fender lip by the 1" minimum margin so it can tuck. Stock 8" rim offset on the rear does look whimpy and needs to be spaced outward on all 3rdgens to make the car look more mean. I have seen many people put IROC fronts onto their rears and the additional 16mm offset from -16mm to 0mm make the car look so much more aggressive- And will not rub the fender.

My rear IROCs are spaced out with a NON-hubcentric regular old 3/8" wheel spacer and they still look whimpy. I can afford to set the back out more another 1/2" on each side and it would look noticibly better. Its the futhest I want to go on regular spacers even though I have 1/2" ARP racing studs. I need to still someday get off my butt and have to rear hubcentric spacers done. I have always pondered the thought of going to some 3pc BBS racing wheels on this car but an not doing another thing to it till the home projects are finished and I thenm finally get around to completing the 3.5L motor I am building for it andput it in to get some power first.

I personally think these would look fitting with my paint scheme?
http://www.hrpworld.com/index.cfm?fo...action=product

3.1EyeCandy

iTrader: (3)

Suppose I never clarified exactly what I'm after. I want what the majority of thirdgenners want:

1) I want the wheels to fit on the car
2) I'm not dropping the car at the same time I put the wheels on, but if I eventually drop it a little to make the gap between the wheels and fender smaller - I'd still like the wheels to fit.
3) I don't want to damage or have to damage (modify the fender, grind anything) anything.

That being said - people can go with smaller width wheels or larger width wheels. This post whould really be directed at the majority of thirdgenners - and the majority of them have stock brake setups, stock wheels, and sagging suspension that almost looks like a drop. The theory behind mentioning brake specs is very important, but don't let that be what people read the most of. Alot of what scares members away from nicer custom wheels and into doing what everybody else is doing is that they don't understand the basics of the theory.

3.1EyeCandy

iTrader: (3)

I'm going to do a series of replies that other people's cars in them. I'm also going to go past the 3 pic limit, as having the pictures in a location that they won't be deleted is crucial to making a post like this informational for the future. If the mod(s) have a problem with this, please contact me and I'll seek some other form of hosting that may not be as permanant.

TheSinister

3.1EyeCandy

iTrader: (3)

Nazzz28

3.1EyeCandy

iTrader: (3)

Here's another pic of rocc4u's car. I like the stance and wheel choice on this car.

rocc4u

Gr89RS

iTrader: (5)

Here's Kandied91z's car. He's running a 19x10 out back with what I believe is a 6.75" backspace on 295/30/19. Perfect position for a 10" wide wheel IMO, of course if you don't mind doing a little modification.

heavy_chevy29

i really like the way my wheel are in the back. if i wanted them tucked under really far i would have left the irocz wheels on it. the boyds really dont stick out that far. the are just about even with the lip on the quarter panel. if the suspension were to completely compress the lip on the quarter would not touch the tire. the whole point of getting the new wheels was to stuff some big meat on them and show them off, not tuck them in the factory wheels.

Shagwell

specs once again: 17x8 front 4.25"bs 245/45/17's, 17x11 rear 8"bs but 4thgen rear, 315/35/17, if "slammed" the rear would probably rub, but at my height(heavy car, eibach sprotline) they've never rubbed, and would hit the factory bumpstops before they could. only "massaging" was cutting the front and rear outside corners off the rear bumpstops. would not have rubbed on the road, only when lifted with tires hanging

as requested: (another angle has previously been posted by Thunderfest)

Shagwell

also, although off topic, I gotta say again...Damn you've got some sweet rides Crazy!

CrazyHawaiian

Hey thanks! Right now they are only eye candy unfortunately, the orange one blew the trans and the green one blew the motor. Plan to have both out on the road within the next 3 months time permitting. Well I hope so anyway!

brdofpry85ta

iTrader: (1)

I have Boyd Magnito's
17x10 w/5.75 B.S I asked for 6.00 B.S but this is what they sent. I could have gone with 6.25 or maybe 6.5 I have 315-35-17 on them right now.
17x8 w/4.5 B.S 245-45-17 may switch to a 255-45-17

I have pics but not good ones. I'll take some more and post them as soon as i figure out how.

3.1EyeCandy

iTrader: (3)

If you've got custom wheels and want to post your specs and pics - do so. If you need help posting the pics, email them to me and I'll post them for you.

hayford1991

3.1 eye candy i have the same question but i am putting in my 1991 camaro rs a set of chrome 5 star 4th gen wheels and i was wondering the offset and spacing i will have to do to get them to fit... so if anyone could help it would be great... thanks

3.1EyeCandy

iTrader: (3)

hayford1991, this site will help you a great deal:

SnkSknrZ28

iTrader: (2)

great thread!!!

I'm very interested in seeing more 315/35-17s. Nice ride Shagwell! You said you are running a 4th gen rear, what is the measurment differece between a 3rd gen rear and 4th gen, i'm interested in getting 17x11s but only if they tuck like that, only i have a 3rd gen rear, what would my backspacing have to be to get a fitmet like that?

I'm guessing 6.75bs ? And how much 'massaging' would be necessary? wheel wheels are massaged already from running 28x11.5 ET streets last year, just curious if i'd need anymore than that.

Thanks, keep the pix comming!

BOTTLEDZ28

iTrader: (9)

good info here for me to work with but maybe I am biting off more then I can chew here. Fisrt off, I have 17x11 wheels in the rear running off a 4th gen rear. I am pretty sure that the specs on my wheels are the same as the ZR1 wheels but I will recheck tomorrow. my problem is that they stick out just a hair to much for my liking.I want them tucked in another inch. Now for my dilema, I can 1: go back to a 3rd gen rear and use spacers and some massaging to the inner fenderwell or 2: narrowing the 4th gen rear about 1 inch on each side or 3: go back to a 3rd gen rear and then have the centers of my rear wheels removed and moved inward about 1.5"-2" in the barrel. Im thinking option 3 is the best bet for me since I dont want spacers on the rear and narrowing a rear end is expensive. I have been quoted at $125 per wheel to move the center inward in the barrel with a one week turnaround. Now the 4th gen rear is about 2" wider then the 3rd gen one and my wheels are sitting just flush with the lip of the quarter now. If I put the 3rd gen rear back in and then place the wheel with tire on it in the location I want it to be and measure the distance from the mounting surface of the brake rotor to the inside center of the wheel then would this be the amount that the center must be moved in? I assume so but I just feel like I am missing something important here. Did I explain this right or are you guys confused here?

Shagwell

Explanation is good - I'm with you.
$125 per wheel to do that...hum, not bad. Yeah, put the 3rd gen rear in, set your wheels in place and measure. I'd set the car on the jack/stands at ride height(suspension loaded) and place the wheel where I wanted it, that way I could stand back and look from different angles to be sure I was happy with fitment. Then measure the distance between the axle and the wheel at the mounting surfaces.

Once mine is done, I'm probably gonna tuck my tires in about 1/2" per side, but I'm thinking the 10-bolt probably won't go back in, thus I can just change the width of the rear since everything will be custom/aftermarket anyway.

BOTTLEDZ28

iTrader: (9)

Someone please explain this, I took some measurments on my wheels today and came up with this. My 17x11s have a total width measurement of 11.5" from inside ring to inside ring. It looks like the BS is 7.5". My fronts(17x9.5) measure 10" with a BS of 6.75". I am unable to measure the offset because I didnt have the prope tools at that time. Do these measurements seem like right for wheels that came off a 4th gen?

Also, I would like to get the center of my front wheels moved in as well but I will end up being stuck with that dreaded huge lip in the front and nothing in the rear due to the design of our suspension. Just look at any GTA wheel. It looks like the fronts belong on the back and vise versa. I will try to move the back in some and just leave the fronts alone with my 2" spacers I guess.

Shagwell

Yes, those numbers sound sbout right for 4th gen spec wheels. - If you put a 3rd gen rear in and have the bs changed to bolt-in w/o spacers, then you could have the fronts changed to eliminate the spacers and come out with the same outer wheel lip front and rear. If you leave the fronts as is with the spacers, then the rear is gonna have (the difference of the spacer) more lip.

BOTTLEDZ28

iTrader: (9)

well I gotta figure out if its worth it to modify 4 wheels($600), switch back to a 3rd gen rear which means basically gutting my 4th gen one and swapping everything but the axles over. Im gonna have to pay someone to set the gears up again since I dont have the tools to do that. Thats gonna run about $250 for someone to do it right. I guess I could try to sell a 4th gen rear with axles along with my 2" front spacers and see if it helps any with the funding of this new I wanna do.

Shagwell

- Which puts the dollar figures back up to the point of just getting new wheels with the correct offset for the look you want. Isn't car modding fun?...