20x12's on a 71 Camaro?

[Zapper]

Hey guys...first post.

I've got a 71 RS Z28. it has stocks leafs in the back on lowering blocks

I've got 18x10 Budnik Sparks in the back with 6" backspacing. I'm also running a 1.25" spacer to push the wheels out to be flush.

Is anyone running 20x12's in the stock wheel wells?

I've done the measurements and it looks like I can clear the 20x12's with a 7" backspace and still clear the leafs and wells.

Looking for anyone's input or feedback....pic below is my car with the 18x10's....plenty on clearance.


https://static1.pt-content.com/images/pt/2014/04/12433844143_8ae894047e-1.jpg (http://api.viglink.com/api/click?format=go&jsonp=vglnk_jsonp_13981209957359&key=3cdd378e1965fd6f40108745a20f47c3&libId=992d0eb9-6725-4b2c-8c2c-2f4a048589f8&loc=http%3A%2F%2Fmbworld.org%2Fforums%2Fc63-amg-w204%2F530470-whats-your-garage-2.html&v=1&out=http%3A%2F%2Ffarm4.staticflickr.com%2F3779%2F1 2433844143_8ae894047e.jpg&ref=http%3A%2F%2Fmbworld.org%2Fforums%2Fc63-amg-w204%2F530470-whats-your-garage-3.html&title=What's%20in%20your%20Garage%3F%20-%20Page%202%20-%20MBWorld.org%20Forums&txt=)

[Schwartz Performance]

I highly doubt you'll fit a 12" rim in a stock wheel well. We usually have to minitub it about 2" to gain that clearance..
Take a pic of the area between your tire and the leafs if you could.

You will need 7.75" of back spacing since your FRONT spacing probably can't be moved outward if you're flush with the lip right? This means you need to have 2" more clearance to the inside.
-Dale

[Zapper]

I highly doubt you'll fit a 12" rim in a stock wheel well. We usually have to minitub it about 2" to gain that clearance..
Take a pic of the area between your tire and the leafs if you could.

You will need 7.75" of back spacing since your FRONT spacing probably can't be moved outward if you're flush with the lip right? This means you need to have 2" more clearance to the inside.
-Dale

The front spacing can be moved outward, since I'm running a 1.25" spacer with the current 18x10's

So, I've got 18x10's with 6" of backspace, and running a 1.25" spacer, to make it flush

If I move to a 20x12, I'm adding 2 inches of width.

If I remove the 1.25" spacer and add the 1.25" to the outside/front of the wheel, then I would need to add .75" to the backspace (1.25" lip +.75" backspace = 2")

This is where I'm coming up with the 7" backspace (which is 1" more than my existing wheel)

It sounds logical but I may be way off or missing something

[71maroesteban]

If you can Fit that in a stock car I applaud you!

[Schwartz Performance]

You said the spacer makes it flush.. What does it make it flush with?

If it's flush with the quarter lip, meaning you cannot replace the 1.25" spacer with a 1.5" one...

Your IDEAL front spacing is your current front space of 4" plus the 1.25" spacer, right? So 5.25" front spacing. Back spacing on 13" overall width is the 7.75" that I am coming up with.

This isn't accurate if you can move the wheel out toward the quarter panel more than your current setup.

-Dale

[Zapper]

You said the spacer makes it flush.. What does it make it flush with?

If it's flush with the quarter lip, meaning you cannot replace the 1.25" spacer with a 1.5" one...

Your IDEAL front spacing is your current front space of 4" plus the 1.25" spacer, right? So 5.25" front spacing. Back spacing on 13" overall width is the 7.75" that I am coming up with.

This isn't accurate if you can move the wheel out toward the quarter panel more than your current setup.

-Dale

Thanks for the feedback Dale!

The spacer makes it flush to the fender lip

You mentioned 13" overall....are you adding an inch for tire width?

If so, would you add that to that backspace of your wheel? Because wouldn't that bring the wheel further inboard if it's 12"

[Schwartz Performance]

No, a 12" rim is measured to where the bead seats, which is 1/2" in on either end. The back spacing is determined by the overall width of 13". Measure your 10" rim end to end and it's 11". Or if you measured the 10" yourself, it's actually considered a 9" rim.

-Dale

[Zapper]

No, a 12" rim is measured to where the bead seats, which is 1/2" in on either end. The back spacing is determined by the overall width of 13". Measure your 10" rim end to end and it's 11". Or if you measured the 10" yourself, it's actually considered a 9" rim.

-Dale

So, wouldn't you take off half an inch of the 7.75" backspace. You've added the entire inch for the 13" diameter to the backspace rather than splitting that extra 1" across front and back.....

Before 1.25" Spacer

94395

After 1.25" Spacer

94396

[Zapper]

Here's a pic of the rear suspension clearance....

This is a shot of the 18x10 wheel on, with the 1.25 spacer, with 285's in the back

seems like there is a lot of clearance

94428

[markss28]

I have a 73 camaro with 19x10 wheel 295/30/19 pilot SS tires. I have 5.5 BS with about 1/2" clearance to the inner well use (BFH mod). And about 1/2" inside wheel lip. That's about as big as u can fit without rubbing. Maybe 305 just for looks but I wouldn't drive it hard.

[Schwartz Performance]

Here's a pic of the rear suspension clearance....

This is a shot of the 18x10 wheel on, with the 1.25 spacer, with 285's in the back

seems like there is a lot of clearance

94428

It looks like you have MAYBE an inch- keep in mind the tires will move side to side slightly when one side is compressed or extended.

Regarding splitting the 1" to the front and back sides...

Could you put your current wheel onto a 1.75" spacer to shove it out another 1/2" and not rub? If so, yes you can split that 1/2" but if it'll rub, then no you'll have to add the whole inch to the "back spacing".

If you have minimal clearance to your quarter panel lip currently, your front spacing cannot change. So if you want a wider wheel, you'll be adding to the back spacing.

-Dale

[Zapper]

It looks like you have MAYBE an inch- keep in mind the tires will move side to side slightly when one side is compressed or extended.

Regarding splitting the 1" to the front and back sides...

Could you put your current wheel onto a 1.75" spacer to shove it out another 1/2" and not rub? If so, yes you can split that 1/2" but if it'll rub, then no you'll have to add the whole inch to the "back spacing".

If you have minimal clearance to your quarter panel lip currently, your front spacing cannot change. So if you want a wider wheel, you'll be adding to the back spacing.

-Dale


Thanks for the feedback Dale....I'm gonna take a 4th set of measurements just to make sure and decide overnight

I'm also going to purchase some offset shackles to move the leafs inboard, about an inch on each side and move the leaf perches, on the rear end, inboard as well, just to be safe

[Zapper]

It looks like you have MAYBE an inch- keep in mind the tires will move side to side slightly when one side is compressed or extended.

Regarding splitting the 1" to the front and back sides...

Could you put your current wheel onto a 1.75" spacer to shove it out another 1/2" and not rub? If so, yes you can split that 1/2" but if it'll rub, then no you'll have to add the whole inch to the "back spacing".

If you have minimal clearance to your quarter panel lip currently, your front spacing cannot change. So if you want a wider wheel, you'll be adding to the back spacing.

-Dale

I used the table below for the calculations and it came out very close to the clearance I have

94439

[Schwartz Performance]

94442

See picture, hope this explains.

Your front spacing likely cannot go beyond the "ideal" otherwise it'll likely hit the quarter panel.

-Dale

[Zapper]

94442

see picture, hope this explains.

Your front spacing likely cannot go beyond the "ideal" otherwise it'll likely hit the quarter panel.

-dale

Yes!

Totally explains it and it inline with my original numbers that i was thinking.

So pretty much for the 20x12, add .75 to the backspace to get 6.75 overall. I was thinking 7 to be safe and add a .25 spacer if i can push it out.

Which would give me the same ideal flush fit i have currently with the 18x10 and a 1.25 spacer.

Thanks so very much Dale!

[cubicylndr16]

some real life exp. I run a proxes 888 315 on an 11.5 rim on my 73'. No tubs and leafs. And its maxed out. Quarter lip is rolled. I run the car HARD and get rubbing in the inner and outer. Nothing major to cause tire damage, but it rubs. Im about 3/8" between the tire and leaf.

https://static1.pt-content.com/images/pt/2014/04/337BF9D281D4403FA00CBE0722A17266_zpsgoy9-1.jpg (http://s28.photobucket.com/user/cubicylndr16/media/337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg.html)

<a href="http://s28.photobucket.com/user/cubicylndr16/media/337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg.html" target="_blank"><img src="http://i28.photobucket.com/albums/c246/cubicylndr16/337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg" border="0" alt=" photo 337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg"/></a>

[srh3trinity]

I think you are going to have to raise your rear ride height to run that much tire. I haven't seen anybody running a 315 and a low stance without a tub. All 315's aren't created equal though. I have 305 ps2's that are wider than some 315 tires

[Zapper]

some real life exp. I run a proxes 888 315 on an 11.5 rim on my 73'. No tubs and leafs. And its maxed out. Quarter lip is rolled. I run the car HARD and get rubbing in the inner and outer. Nothing major to cause tire damage, but it rubs. Im about 3/8" between the tire and leaf.

https://static1.pt-content.com/images/pt/2014/04/337BF9D281D4403FA00CBE0722A17266_zpsgoy9-1.jpg (http://s28.photobucket.com/user/cubicylndr16/media/337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg.html)

<a href="http://s28.photobucket.com/user/cubicylndr16/media/337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg.html" target="_blank"><img src="http://i28.photobucket.com/albums/c246/cubicylndr16/337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg" border="0" alt=" photo 337BF9D2-81D4-403F-A00C-BE0722A17266_zpsgoy94lld.jpg"/></a>


Thanks Cubic!

That's just the feedback I needed.

I'm going to get some 1" offset shackles for the rear leafs to move them an inch inboard, and give me a little extra clearance. Ordering some new rear perches for the axles as well.

I won't be running mine as hard as yours, so I think I might be able to get away with it. I've measured it out five times now, and keep getting the same results, so I'm going to pull the trigger.

[Zapper]

I think you are going to have to raise your rear ride height to run that much tire. I haven't seen anybody running a 315 and a low stance without a tub. All 315's aren't created equal though. I have 305 ps2's that are wider than some 315 tires


In the configurator pic I posted above, It looks like a 315/25/20 is only 1.2", obviously wider than the 285's I'm running now, depending on the brand. Since that extra width is going to move to the backspace, it will definitely be close.

[markss28]

I think that's a lot of tire to fit but if ur going to move the leafs in u may need to change ur gas tank to something smaller or narrowed. I say buy a tire first to see if it will fit

[Zapper]

I think that's a lot of tire to fit but if ur going to move the leafs in u may need to change ur gas tank to something smaller or narrowed. I say buy a tire first to see if it will fit


Thanks Mark!

Good idea on the tire.

You don't need a narrow gas tank if you move the leafs in just an inch.

If you go with the DSE shackles they you would have to narrow the tank as they are 1.75"

[BEEBE]

Zapper , Who has shackles that are only 1" offset? Thanks

Beebe


Thanks Mark!

Good idea on the tire.

You don't need a narrow gas tank if you move the leafs in just an inch.

If you go with the DSE shackles they you would have to narrow the tank as they are 1.75"

[Zapper]

Zapper , Who has shackles that are only 1" offset? Thanks

Beebe


They are the ones from American Made. They are Mopar ones, but used universally as well.

They have several adjustment points so they can definitely accomodate the Camaro leafs as well

http://www.americanmuscle.biz/ProductDetails.asp?ProductCode=35610&CartID=1