Offset & Backspacing? Need help for torq thrust 2 wheels - 4th F-Body

firebirdmuscle · February 8th, 2010, 08:05 PM

what is the difference between offset and backspacing? whats the normal everybody runs on them. I'm planning on gettin 17x7 in the front and 17x11 in the rear. Any information would be extremely helpful becuase this is whats holding me up from getting them.

circlelt1 · February 8th, 2010, 10:18 PM

Backspacing is the measurement from the inside lip of the wheels to the hub-mount. The offset is the measurement from the middle of the wheel to the same hub-mount.

My zr1's are 17x9.5 all around and have i think about 8 inches of backspacing (havent measured), and they DO have an offset of +50mm. Then some aftermarket zr1 wheels aswell as others that have been used on 4th gens have an offset of +36mm. So if its somewhere in there you're good to go.

For 4th gens, the more backspacing the better (4-5in on your 7s, and 8-9 on your 17x11s).

RrCoX22 · February 9th, 2010, 02:08 AM

there's also a negative and positive offset... depending on where the hub mounting surface is located. if it's closer to the the outside (hub cap) it's positive and more toward the inside (brakes) it's negative.

Ideally you want to have a larger width for increased handling or traction with similar offset to stock

circlelt1 · February 9th, 2010, 03:55 AM

Well its like with me switching to the 9.5 zr1 wheels and a 275 tire, compared to the z28 wheels and a 245 tire that i had last season.

With the 275's being 1.2in wider each, thats an added 2.4in track width plus with the extra offset of these wheels and them being 2 inches wider than factory z28 wheels.

So being set-up like that, in both front and back outer sidewall to outer sidewall ill have an extra 5-6in of track width.

firebirdmuscle · February 9th, 2010, 06:41 PM

okay, thanks. so the backspacing should be 4-5 on the front (17x7) and 8-9 on the rear (17x11)? now what about the offset? how should that be?

RrCoX22 · February 9th, 2010, 07:39 PM

offset is more so relating to the width of the wheel. which a larger wheel you will want larger backspacing to bring the tire closer to it's stock track

circlelt1 · February 9th, 2010, 10:20 PM

This is what happens when you buy wheels before checking them for offset and backspacing on your car. This was 3 yrs ago and These were 9inch wheels with only 4 inches of backspacing with negetive offset to boot.

Now this is with the correct backspacing and offset:

firebirdmuscle · February 11th, 2010, 06:56 PM

thanks for the pictures. okay, so what does this sound like to yall? tell me if this sounds right for the backspacing and offset.... 0mm offset with 4.0" backspacing on the 17x7 and a +45mm offset with 7.75" backspacing on the 17x11. Is that good numbers for them?

firebirdmuscle · February 13th, 2010, 06:19 PM

and this also, which sounds better for our cars... -11mm Offset and 4.0" Backspace or +8mm Offset and 4.75" Backspace on a 17x8 tt2??

rooster99ss · February 13th, 2010, 08:09 PM

if you don't mind me asking, why are you going so narrow on the front wheels? most f-body guys go with a 17x9.5 on the front, that's the same size as the ZR-1 wheels

firebirdmuscle · March 16th, 2010, 07:22 PM

rooster, got some new info. I went to the local rim shop today to get started on the rims and i come to find out that the 17x7 or x8 will not work on our cars for some reason dealing with the offset and backspacing, so the guy said anyway. he called american racing and got pretty much the same feedback and the AR rep said that only the 9.5 and 11 will work on our cars. so with that being said, looks like I am going to go with the 17x9.5 in the front and 17x11 in the rear. now the local shop told me that the wheel is made when you order it, which i already knew, and when i do order it and they ask for what kind of car, that when I tell them a firebird that they will build the wheel accoringly without me having to give them any specific backspacing or offset? and once agian that was straight from american racing. should i just do that or should i have a specific offset and backspacing to give them. I'm not wanting anything off the wall just around what everyone else is running on theirs.

RrCoX22 · March 16th, 2010, 08:38 PM

what are your plan for the vehicle? would like a deep dish?

firebirdmuscle · March 16th, 2010, 08:46 PM

exactly what do you mean by plans for my vehicle? and no, not really. i would like mine to be like in your old z-28 / roosters ride. i really like the way both of y'alls is

rooster99ss · March 18th, 2010, 09:30 AM

Quote:

Originally Posted by firebirdmuscle

rooster, got some new info. I went to the local rim shop today to get started on the rims and i come to find out that the 17x7 or x8 will not work on our cars for some reason dealing with the offset and backspacing, so the guy said anyway. he called american racing and got pretty much the same feedback and the AR rep said that only the 9.5 and 11 will work on our cars. so with that being said, looks like I am going to go with the 17x9.5 in the front and 17x11 in the rear. now the local shop told me that the wheel is made when you order it, which i already knew, and when i do order it and they ask for what kind of car, that when I tell them a firebird that they will build the wheel accoringly without me having to give them any specific backspacing or offset? and once agian that was straight from american racing. should i just do that or should i have a specific offset and backspacing to give them. I'm not wanting anything off the wall just around what everyone else is running on theirs.

awesome man, that's the way I would go! all you should have to do is tell them that it's for a firebird and they should do the rest

Quote:

Originally Posted by firebirdmuscle

exactly what do you mean by plans for my vehicle? and no, not really. i would like mine to be like in your old z-28 / roosters ride. i really like the way both of y'alls is

our wheels are deep dish bro (in the back)

firebirdmuscle · March 18th, 2010, 11:41 PM

rooster, did you order all new rims or did you just paint them black and leave the polished lip? looks good either way just wondering though. and i thought deep dish was when the wheel was as far as it could go inside the rim or whoever you say it

youngrigo aka NVEEOUS · March 19th, 2010, 12:30 PM

I have an extra pair of chrom ZR1's that are 17x9 and im turning them to 17x7 for the front for when i go out to the track... you can run 17x7 just need the right offset.

rooster99ss · March 19th, 2010, 04:34 PM

Quote:

Originally Posted by firebirdmuscle

rooster, did you order all new rims or did you just paint them black and leave the polished lip? looks good either way just wondering though. and i thought deep dish was when the wheel was as far as it could go inside the rim or whoever you say it

LOL, i haven't paid for a set of rims on my car yet, as far as just going down and buying some, hahaha

the TT2's that were on the car, i traded the stock silver ZR1's that were on my car plus $300 to get those from a friend. Ran them for a while, got tired of polishing them, wound up jumping a curb and bent both of the left side rims......

then about 3 weeks later, came across another buddy that had these black TTM's on his car, only a month old. Traded me straight up......lol. These rims come powdercoated black the way that they are.

Here's a link to where you can order a set. All the backspacing info is already there, the 17x9's are for the front, the 17x10.5's are for the back - exact same setup i have. just pay and have them shipped:

http://www.tirerack.com/wheels/Wheel...All&sort=Brand

firebirdmuscle · March 20th, 2010, 12:35 AM

you just getting all the deals aint cha, sounds like i need to come to texas for a bit and meet some of those good folks, lol nice deals

rooster99ss · March 20th, 2010, 03:03 AM

I come across some good deals, LOL.

ask me how many times my car has been tuned and how many times i've actually paid for a tune

firebirdmuscle · March 21st, 2010, 04:40 PM

how many times?