joekickass

hi, Kandied91z

I know my rear wheel is not "right" but I just try to get the biggest wheel in the rear, the people here don't thought I can go more than 235/40/18 both front and rear and very not happy to see what I do , are you aggree ? I believe you didn't run 235/40/18 on your car both front and rear, even they the closest number to the stock. for the 8.5 rim, you said I can go bigger, that waking me up, I just try 255/45/18 in the front but it rub, can I try 255/40/18 and no rub, any idea??

Kandied91z

iTrader: (7)

i'm having a little trouble reading your responses...lets tackle each problem separate starting with the front wheels.

here is my setup. stock to what i'm driving:

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
245/50-16 4.8in 12.8in 25.6in 80.6in 786 0.0%
245/40-18 3.9in 12.9in 25.7in 80.8in 784 0.3%

i have an 8" wide rim so the 245 "width is just right...the stock rim was also a 8" rim. you want to run a 8.5" rim so you need to go wider on the tire to a 255. because your going wider to a 255 for your 8.5" rim you will need to adjust the profile acordingly. now if it were my choice on a 8.5 rim i would probably go with a 255/40/18 tire

here is a calculation for stock versus a 255/40/18 setup:
245/50-16 4.8in 12.8in 25.6in 80.6in 786 0.0%
255/40-18 4.0in 13.0in 26.0in 81.8in 775 1.5%

what would be wrong with this tire size? what are you trying to accomplish in the front?

Kandied91z

iTrader: (7)

now lets discuss the rear!

what do you want to do in the rear. the best idea is to keep your tires closer to stock specs...meaning you can have a wider tire but you want to keep things even. are you wanting a "fatter" tire meaning something that looks like a drag car? if you are 18's are the rim for you.

again for this setup you should use the same as the fronts....changing tire sizes that aren't right for a rim causes problems and throws off many things.

again i would go with the 255/40/18:

245/50-16 4.8in 12.8in 25.6in 80.6in 786 0.0%
255/40-18 4.0in 13.0in 26.0in 81.8in 775 1.5%

if you want a wider tire go with a wider rim. if you want a taller tire for more traction go with a smaller rim. what is it your trying to do with the rears?

Kandied91z

iTrader: (7)

samdog there are plenty of cars running 10" wide rims on this site with lots of pictures. i know i have posted way to many and you can find some of crazys boyds as well. all the pictures i currently have are too dark. just add 2" to the inside visually and you'll get the idea.

joekickass

hi Kandied91z

Sorry for my english and thank you for the advice, I don't understand the effect of the rim wide but now I may know more, I don't want to run the correct tire before because I want to go fatter, so I pick up a bigger tire for the rear(255/45/18), it looks great then I got a problem to the front tire, it could not go too fat because there is not enough space, but now I know I may go 255/40/18 in the front, the 235/40/18 looks too narrow for the 8.5J rim, thank you.

one more question, my rim is 8.5J, +15mm offset, is it correct?

Joe

Kandied91z

iTrader: (7)

well the 235 is too narrow. you need a 255 to be lined up properly. i do not know what the j is in the 8.5 rim but a +15mm offset will not work for the front without an adapter of sorts. the rears it would be close since i believe stock is +16.

if you want a fat tire look your going with the wrong rims....18's are a low profile wide tire. your looking to do the wrong thing with those rims.

good luck with it.

samdog1232000

That is just fuzzy math!!! Just jokeing.............. You said that you have posted a ton of pics with ten inch wide rims in the back? Can you give me some of the links? This might be pushin it but have you seen a 11 inch wide tire in a camaro before in the rears?

vexter

iTrader: (3)

A couple of things:

First, the url that CrazyHawaiian was referring to is http://www.skulte.com/adapterfaq.html. Andris provides a good explaination of how backspacing is determined. Spend a little time actually following the formula's and you'll end up with a good understanding of how it works. Go there and get yourself up to speed.

Second, Kandied is right on the money with the tire sizes. Its important to understand how tire sizes are labeled as there tends to be a lot of confusion here (i.e. many people will tell you 50's are wide, which depends on your perspective). Simply put, on a 245/50-16, 245 indicates the width of the tire. The 50 is an aspect ratio of the sidewall height in relation to the width. What Kandied is trying to tell you is that if you want to keep the same overall outside diameter (as stock), you need to compensate with this ratio. In this case, moving up to a 255 (width) and dropping the aspect ratio (40-45) will give you a wider tire that has close to the correct height.

In my case, I'm looking at 17x9.5 all around. I'll be running 275/40-17's on all four corners (although it will be tight up front). That will give my a bit wider tire on all four corners and still have the stock tire height.

In the case of joekickass's 18's, I'd be running the 255/45-18's on the fronts also. My $.02.

joekickass

hi vexter,

I have tried 255/45/18 in the front, but it rub, maybe I am not using the right rim, they are 8.5J & +15mm offset, so I asked to Kandied91z if he know about that, tried the calculation on the SKULTE web site and confused, look like I need no spacer for the front, and my rear rim should stick out!!! it is not true......make me so confuse, can any body help me on this???9

joekickass

According to the calculation on the SKULTE web site, my rim is 8.5J, 15mm offset and I got this

Front = 5.09, rear = 5.09

The 89 Camaro can fit rims with a maximum of 5" front and 5.85" rear backspacing -said by Skulte

So I got this:

Front spacer : 5.09-5 = 0.09
rear spacer : 5.09 - 5.85 = -0.76

Is that means I need 0.09" spacer in the front and no spacer need in the rear ?

Can I put no spacer both front and rear?


Joe

dgravois

iTrader: (2)

i used to work at a wheel shop. i have put 21's on a third gen with minimal rub when turning the wheel completely either way. I've done up to a 23 on 94-96 impala ss's and 24's on a lot of big body GM's from the 60's and 70's. email me for fitment questions.

vexter

iTrader: (3)

Hi Joe,

Your calculations are correct. When you say that the 255's rub in the front, where are they rubbing? If it's on the inside, then a small shim should be all you need. Again, 5" is right at the limit for front backspacing. If you're experiencing rubbing when the wheels are turned to the stops, then tire size would probably be the issue. Personally, I'd be willing to deal with a little rubbing when turned to the stops.

As far as the rear is concerned, that 5.09" backspacing is pretty close to stock. So, the outside lip of the wheel should be with .25" of a stock wheel... a difference that probably isn't noticable.

In short, I'm guessing your fronts are rubbing on the inside with the 255/45's, in which case a small spacer should be your fix. The rears should be good the way they are.

Got any pics?

Hope that helps...

vexter

iTrader: (3)

With respect to the rear backspacing, remember that the 5.85" figure on Skulte's site is maximum backspacing. Stock rear backspacing was 5" which you're pretty close to with your wheels. Hope that clears up some confusion.

joekickass

Hi vexter,

thank you for your opinion, when I put 255/45/18 in the front and turn the wheel completely, see the attached drawing to know the side of rub....I know the drawing looks sucks.

Now I put 235/40/18 in the front but thought they are too small for 8.5J rim, I don't think that spacer can make enough room to fit 255/45/18, seem no one have put the tire that big in the front ....maybe try 255/40/18 next time, I still waitting for my custom center ring for those BMW Rim and complete the setup, I will post pic after I finish.

The position of rear wheel looks O.K, I thought they need no modification, according to the calculations, I need a pair of 0.9 inch spacer in the front, but they are so thin(3mm) and maybe not necessary.......how do you think?? I thought I need more than 1cm room to load 255/45/18 in the front with no rub (I mean 255/45/18 is 1or 1.5cm thicker for the space ), do you think the spacer could help, due to the design of 3gen rim, I have to custom another center ring with 3mm spacer on it, take more time and money....but if it is possible to load fatter tire, I will still do it.

sorry for my english.....

Joe

Graboid

I found out that everybody here in this forum tends to put too wide tires on their rims. An 8.5 inch rim is 215,9 mm wide. So why the heck should a 235 tire be too narrow? As a matter of fact it is too wide! The perfect fit for the rim would be a 225. I have 225's on my 8 inch front wheel. The rim is an idea (half an inch) too narrow.
AND, 235 mm is (as long you buy a japanese product) measured on the profile. European and US companies measure the whole thing. Therefore, a bridgestone (JP) 225 is as wide as a goodyear (US) 235. Go to the tireshop and check it if you don't believe it.

vexter

iTrader: (3)

Hi Graboid,

I understand that the actual width of the same sized tire can vary from mfg to mfg. However, GM specified a 245/50-16 for my Camaro which came with a 16x8 wheel. I don't know what to say except "that's stock!" Don't forget that an 8" wheel also has two .25" lips (inside & outside) Unless you're game for some curb rash, I'd avoid a tire that's narrower than the overall width (including the lips) of a wheel. As I see it, the issue that joekickass is contending with isn't the fact that a 255 is too big for an 8.5" wheel. The problem is stuffing it diagonally into his wheelwell without rubbing (i.e. when wheels are turned to the stops). One solution is to run undersized tires in order to make room. If you're okay with that, that's great. However, my personal tastes would drive me to (1. Live with a little rubbing at the stops... or (2. Make more room in the wheelwell.

Btw-- You have one SCHWEEEEEEEEET @$$ED ride!

Also, here are some pics of Andris Skulte's Camaro. In these pics, he's running a 17x8.5 in the front which were mounted with 245/45-17's. I think they look pretty tame.

Graboid

yes, 245's are stock on a 8 inch rim. But the ugly fendergap is stock as well. As we all know, stock doesn't mean good or good looking. If a 9 inch rim was cheaper than a 8 inch rim, gm would have used them

vexter

iTrader: (3)

I have no problem with that. However, I see that as a totally different argument than whether or not a 255 is too big for an 8.5" wheel.