Fbodynut04

Okay, i bought some Torq Thrust II's for my Z yesterday off ebay, havn't told the guy what my backspacing and stuff needs to be... HELP! my car has the 15" aluminum wheels and im not sure on back spacing/offset... and by the way...offset...tell me a little about it, as in, what difference does it make?

on the new wheels, im running BFG Radial T/A's on the factories, 235/60/15, and they rub upon sharp turning, kinda pisses me off... do you think i'll have that problem if u use the same back spacing and offset but with a 15x8 wheel??
any info quick fast and in a hurry would be AWESOME. THANKS!!!

BretD 88GTA

Backspacing refers to the distance between the wheel mounting surface and the outside edge of the rim. It's important to have the right backspacing or else your wheels will rub.

Do you know the offset of the wheels you bought? If so, you can calculate what the backspacing is. Offset is usually given in millimeters – for example, +25mm, -6mm ...etc.

The factory 16x8 mesh GTA wheels use a "0" offset on the front and +16mm in the rear. This gives a front backspace of 4.5" and rear backspace of about 5.25"

For the factory 15" wheels, you could do a search and probably find the backspacing and offset info.



Here's an easy way to help determine backspacing by using the offset value. I just went thru this buying wheels for my 4x4 truck.

An 8" wide rim actually measures 9" from outside edge to outside edge. (Advertised rim widths are determined from measuring the distance between the inner beads)

So, an 8" wide rim with "0" offset will have 4.5" of backspacing (9 divded by 2). Next, there are 25.4mm to an inch, so 6mm is equal to about .2" (let's call it 1/4"), 12mm is equal to about .5" ...and so on.

Based on that, 16mm should be close to 5/8 or .625". Now, a +16mm offset should yield about a 5.125" backspace. I'd call it 5.25" to be safe.

One last thing to remember is that positive wheel offset will increase backspace, while negative offset will decrease backspace.

If you want to see a diagram of what I'm talking about go here:
http://www.discounttire.com/dtcs/infoWheelOffsets.dos


Hope this helps.

83 Crossfire TA

iTrader: (2)

With a 15x8 you pretty much have to run a 4.5” backspace on the front (5” would put the tires in the wheel wells the same as stock, but the wider wheel would hit the tie rod)

On the back 4.5” would look about the same as running 16” fronts on the back, 5" will fit like the stock 15x7's and about 5-1/8” - 5-3/8" will fit about the same as a 16” rear.

Fbodynut04

okay, bret, thanks for the info. very helpful but confusing.. to be honest the diagrams on that link were what made it all "click"...
on this auction i "won" its stated, the guy's an American Racing dealer and you just tell him the backspacing and bolt pattern when you pay... well as im awaiting "Confirmation" of my bank account on paypal, i bought some time, but limited at that, i THINK i know what i wanted to find out now..
what do you guys think would look best? say, 4.5 BS up front and maybe 3.5 out back? give it a nice look or maybe, 4" front and back to give them a little depth but not like HUGE... i popped the wheel of my car today and i believe i got 4".... and remember though, i have rub.. passenger wheel only , sharp turns only... very very strange... im thinkin i want the new wheels to be a little further away from the inner wheel well than that, but then again running an 8" wide wheel will help, correct? or should i maybe give 'er another .5"??? maybe 3.5" BS all round??????????? any suggestions would be sweet, maybe even pix of a car w/8" wide wheels and their offsets... thanks again..

Fbodynut04

by the way, just checkin out Am.Racings website, looks like for the 15x8's you can have either 3.75 or 3.75 and it has a -18m offset... idk if im d-d-dumb or what but if im readin right its one size or none..??
i wonder if i can get the series 405 because they offer more options....
http://www.americanracing.com/wheels....asp?section=V
in the auction http://cgi.ebay.com/ebaymotors/ws/eB...MEWA%3AIT&rd=1 , its stated that they're "Polished Torq Thrust II's" says nothing about which model... im going to promptly email the guy and find out which they are.. ill get back to ya'll on that if he gets back to me..

83 Crossfire TA

iTrader: (2)

You won’t be happy with offsets that move the wheel out past the centerline (backspacings less then 4.5 on an 8” wheel) unless you want the wheel/tire to stick out.

To give you an idea here’s a couple pics of some 16” TT2’s on my formula:





the back wheel is a 16x8 with 4.75” BS with a 295/50/16 tire on it (and yea, that an 1” taller then what I wasn’t able to find anyone that actually managed to wedge the whole tire inside the wheel well in the thread that I started about a month ago).

It doesn’t touch anywhere but it is pretty much maxed out, for a daily driver or if you wanted to mount the same tire on a wider wheel you’d have to move the offset in a little or roll the fender lip. It looks like you can go in another ¼” (5” BS on an 8” wheel) without contacting anything on the inside, but of course, my wheel wells have had some minor hammering done to fit some 275 60 15 DR’s (bigger and wider then a normal radial) on a ½” offset tire already. With a 10” rim I’d probably go with something in the 5/8”-7/8” offset, 6-1/8-6-3/8” BS) and do whatever hammering/cutting is necessary of the inner to make it fit right. (yes, I much prefer a big tire that actually stays inside the wheel well).

Fbodynut04

well, after thinkin about it, and lookin at my car, i think tha that those factories are tucked wayyyyyyyyyy to far in there, and they're on a 4"BS, SO, im thinking that a 4" bs on the TT2's is what im gonna want, i dont want them stickin way the f out there like a damn low rider, but i want it to have a sorta agressive look...
remember im only gonna be runing 235/60/15's on these.. for now, so i dont hafta worry too much about wheel well clearances and such. i think that the 4" will put them out there a tad, but also keep them under the "lip".. Thanks for the help and info guys, you were very helpful. ill definately post pics when i get the new wheels and stuff.

BretD 88GTA

I don't think 4" of backspacing on an 8" wide wheel is going to work. The wheels will stick out too far and rub on the fender lips. They may also rub when turning.

IMHO, 4.5" of backspace would be better. You will definitely be fine up front. 4.5" in the rear might require rolling the fender lip up to ensure they don't rub.

Fbodynut04

ok, not to say you're wrong or anything here but AmericanRacing says that for 82-88 camaros, they reccomend a backspacing of 3.75" with an offset of -17.78mm.. assuming they've actually tried the combo... i just figured that 4.0 would pull it in a little more yet not tuck them in... i dont mind if the tires stick out a little more that what they do now, cuz right now they're round about 2" inside that upper lip, im hoping that they will fit allright.. oh, and on that note, as of 11:30(cst), the wheels are paid for, and should ship soon... ordered them w/a 4" BS...the way i see it, if they dont fit, they'll sit in the corner until i buy another vehicle they'll fit on, OR ill turn around, sell them on ebay and hopefully make a profit . allright, thats my for now..

BretD 88GTA

Hmmm, if that's what American Racing specs. out, then yes I'd go with their numbers. Let us know how the wheels fit.

83 Crossfire TA

iTrader: (2)

Why can’t people just listen.

Yes, the stock 15’s do put the wheels in too far. The stock wheels have 4.5” BS on a 7” wheel. I’m suggesting that you use a 4.5” bs on an 8” wheel to move them out some.

ARE does recommend -16 or -18mm offset for 3rd gens. We got a set in the shop roughly a month ago (some 16’s). I said they wouldn’t fit when they came in, they tried them anyway and they didn’t. Ended up replacing them with the next size over in that particular line which was 8mm offset 16x8s which fit fine on all 4

Fbodynut04

chill out man, i DID listen to your advice, dispite your thoughts. my original thoughts were to get a set of reverse offset wheels for the back and maybe 3.75bs up front, but after your guys' advice and helpful hints, i decided not to..i just want to pull the wheels out a lil more... sorry to dissapoint, but this is also my decision on the wheels i paid for.. i've done some researchin a little more on the topic of backspacing and such since you guys first started replying in the thread and i DO understand what im doing, and like i said before, if they DONT fit, i'll just turn around and sell them, no sweat off my sack..

Fbodynut04

okay, finally got my wheels, and got them on.
I was un-able to get the 4" B.S. that i wanted, due to the fact that it would have cost me another 150 bux. The pix will be on my site here soon http://www.cardomain.com/memberpage/500526
check that out and tell me what u think the B.S. is on them...
oh, look on page 2, thats where ill have the pix..