backspacing questions

[woody80z28]

How much work do you think it would be to make these fit?

American Racing Rebel - black aluminum
http://store.summitracing.com/partde...5&autoview=sku


I've found them in a few possible sizes.
17x9 - 6" bs
18x9 - 6" bs
18x10 - 7.125" bs

I have this written down for ideal sizes for a 2nd gen.
Front: 17x8 w/5"bs
Rear: 17x9.5 w/5.5"bs

Since these have more backspacing than I need, I should be able to run them with wheel adapters, right?

[SHANE 73Z]

Hey woody,

I dont know what happened to Todds80Z28 page but he had the spacer sizes he used for his 17x9s all the way around on his car.

They will be different for these wheels, but just to guess I would say you are going to need a .25"-.5" spacer in the front & .5"-1" spacer in the rear. IN that size range you are going to have to upgrade to long studs and maybe even go to 1/2" studs.

Shane

[dannyUAL767]

Woody, like you, I've got a 1980 Z28 and I want to put AR Rebels on it. Have you looked at my thread that I started a while back? Here it is: http://www.nastyz28.com/forum/showthread.php?t=98483

Like Shane said, we'll have to upgrade to long studs but I don't know anything about the 1/2" studs .

BTW, check out this "chinese brake" thread that I started on corral.net: http://www.corral.net/forums/showthr...=970209&page=2

Scroll down to post #38 by Cougar5.0; the very last paragraph. He says that his American Racing wheels were made in china ! Hopefully the Rebels aren't made in china because I won't put chinese junk on my car !

[Todd80Z28]

My page is back up, right here on Nasty. See sig.

A 1" wheel adapter for the rear (to get the 9" wheel at 5" BS, which works) might be an issue. The stud length plus the height of an acorn nut likely adds up to more than 1", which means you won't have a flat surface for the wheel to sit against.

Somebody may have figured out a workaround for this. The two big boys making adapters that I know about are www.vettebrakes.com and www.skulte.com. Your best bet is to call and ask.

Up front, since you only need a 1/2", long studs with a spacer (just a ring that slips over existing studs, rather than bolting on, like and adapter would) would probably do. These make me nervous, in general, but if you use good studs, it shouldn't be a problem.

17x9s all around, with 5.5" BS up front, and 5" BS out back is a good target to shoot for. It doesn't give much room for error, though. If you don't have Z28 bumpstops up front, an 8" wheel on 4.75"-5" BS is better. Out back, if the rear moves much side to side, bring the wheels in 1/4" there, too, or roll the fender lip a little bit.

Todd

[dannyUAL767]

Originally Posted by Todd80Z28

My page is back up, right here on Nasty. See sig.

......17x9s all around, with 5.5" BS up front, and 5" BS out back is a good target to shoot for. It doesn't give much room for error, though. If you don't have Z28 bumpstops up front, an 8" wheel on 4.75"-5" BS is better. Out back, if the rear moves much side to side, bring the wheels in 1/4" there, too, or roll the fender lip a little bit.

Todd

Todd, I've owned my 1980 Z28 since it was brand new. It came with the optional 15X7 aluminum wheels. Years ago, I measured the backspacing and came up with 4 7/8" from the mounting hub to the rear of the rim. This is just a hair under the 5" that you say is a good target for the rear spacing.

My car is at my parents' house in SC so I can't take a look right now. I know that the rim and tire isn't anywhere close to hitting anything out back. 6" of backspacing (Rebel wheels) may be hitting stuff, though.

[1FstChevy]

wheel adapters from Skulte Performance are your best bet, 4.75BS is going to be your safest bet on the front as 5" can rub aftermarket sway bars and such, but more than 5" has also worked for some people. Then on the back your correct that 5.5BS will work well for a 9.5" wheel but still measure before ordering!

www.skulte.com

Avoid spacers if your going more than .5" and I'd also jump on ARP high strength studs, regardless on what wheels you get since it can't hurt. I saw a Galaxy last summer that drove right off the highway when the original late 60's studs fatigued and the rear passenger wheel went flying! Luckily for them there was a LOT of grass to slow them down beyond the emergency lane, but I'm sure it was still a fun ride!

[dannyUAL767]

Originally Posted by 1FstChevy

wheel adapters from Skulte Performance are your best bet, 4.75BS is going to be your safest bet on the front as 5" can rub aftermarket sway bars and such, but more than 5" has also worked for some people. Then on the back your correct that 5.5BS will work well for a 9.5" wheel but still measure before ordering!

Okay, it looks like 5.5" backspacing will work out back. That means that I'd need a 1/2" spacer to make the Rebels work. Now I've got to solve the front issue .

[woody80z28]

I've also been looking at C6-R wheels, black with the machined lip. They look to be available in 18x8.5/56mm for $125 and 19x10/72mm for $165.


I can't really tell if I could make the 19x10s work, because the calculator I'm using online only goes to 55 offset.
http://www.rims-n-tires.com/rt_specs.jsp

But it looks like 18x8.5 all around is a real possibility.

[3SLO5]

better choice is the ones for a corvette, i wouldnt trust any shimmed spacers that are not bolt on over 1/4 inch without 1/2 studs. the corvette wheels will need like 2inch spacers that bolt on and that is better. and danny factory rims 15x7 came with 4/14 backspace not close to 5 inch, if they had that much with such a small diameter rim it would lock up against the controlle arm and not spin.

[woody80z28]

Originally Posted by 3SLO5

better choice is the ones for a corvette, i wouldnt trust any shimmed spacers that are not bolt on over 1/4 inch without 1/2 studs. the corvette wheels will need like 2inch spacers that bolt on and that is better. and danny factory rims 15x7 came with 4/14 backspace not close to 5 inch, if they had that much with such a small diameter rim it would lock up against the controlle arm and not spin.

Weren't the steel wheels 15x7 and N-90s 15x8?

Does anyone know the backspacing on the 15x7 steel wheels off hand? Mine are in the parents' garage with tires mounted.

[woody80z28]

These don't look bad, although the tire sizes could be better. 17x8 with 235/45/R17 and 17x9 with 275/40/R17.

http://cgi.ebay.com/ebaymotors/17-CA...spagenameZWDVW

[woody80z28]

Or, for the price, why not 20s?



http://cgi.ebay.com/ebaymotors/20-BL... Z330191407140

$740 for wheels and $486 for Z-rated 245/35R20 and 255/35R20 from tirerack.

[Todd80Z28]

4.75BS is going to be your safest bet on the front as 5" can rub aftermarket sway bars and such, but more than 5" has also worked for some people.

I assume you're talking about an 8" wheel. No 9" wheel is going on the car at 4.75" BS- it will hit the fender lip, and probably rub the wheel well on full lock turns as well.

Woody- Don't sweat the backspacing of factory wheels too much, because you're upsizing the width. That changes the picture, because now you've got to tuck more wheel into the well somehow. What I've figured is-

Front- these numbers are for cars with Z28 bumpstops. Without them, I'd go in another .25" or so.

16x8- 4.75" BS (5" will scrub the upper control arm lip on full lock turns)

17x8- 4.5-5" works
17x9- 5.5"
17x9.5"+: Good Luck

Rear- I prefer the wheels out closer to the fender lip. Not rubbing on squat, but out more than the factory look. Rear track width is over an inch narrower than the front, so you have some opportunity to "square up" the look a little.

16x8- 4" works, 4.25" is better.

17x8- as above.
17x9- 5"
17x9.5- 5.5"
17x10- 5.75"
17x11- 5.75" to 6", might have to beat the selt belt hump, and roll the lip.

18+" wheels, see 17" specs.

When dealing with offset (from wheel centerline) numbers instead of backspace, what I do is take the wheel width, add 0.5", then figure backspace from there based on offset. The 0.5" accounts for the rim lip that isn't figured into the stated width- somebody here clued me into that years ago.

So, a 19x10 with a +72mm offset should be 10.5" or 266.7mm wide. Wheel center is 133.4mm, so backspace is 205.3mm or 8.08". 2.25" adapter would put you at 5.83" or a 2.5" adapter would set you at 5.58".

[1FstChevy]

Hey, 20's aren't allowed!!! I personally like that "C6R" style wheel more than the American racing Rebel wheel, especially considering the price. You might be able to run a 19" in the back with a 305/30/19 but @ that diameter and up you're actually decreasing your performance by increasing inertia, not to mention tighter tolerences that'll get on your nerves when tires start rubbing.

and +1 on what Todd said above, pretty much boils down to 4.75BS & 5.75 if your running a safe 8" & 10" widths that aren't going to cause a bunch of tight clearance issues.

& those other American Racing "M" wheels as I think is part of their title, are technically a Mustang replica wheel, I had considered them at one point but didn't think they had much going for them.

[woody80z28]

I don't really think 20s will be a problem as far as performance is concerned. I have 15s with drag tires for time spent at the track. And I have 17s on my Beretta and would like something bigger.