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Discussion Starter · #1 ·
I'm hoping someone has the same front end setup as mine! I want to put different wheels on and the fronts are rubbing now that it's lowered. Here are the specs:

- Earle Williams 2" drop spindles
- Chevelle disc brakes
- tubular upper arms with +5
- power steering, not sure what box it is?
- 60.65" from mounting surface to mounting surface

Is anyone else running this setup? If so, what backspace do you have? I'm looking at either 17x8" with a 215/55 tire or an 18x8" with a 225/50 tire. Tire calculator says 5.25 to 5.5" backspace will work but was hoping somebody has this on their car already and can tell me it works with no rubbing. Thanks in advance!!
 

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I may be wrong...But, I didn't think you could put Chevelle type discs on dropped spindles.
 

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Discussion Starter · #3 ·
I called Earle myself and sent him a pic of the caliper and rotor. He said it was the big GM caliper so I figured it was from early Chevelles. I had to send him a rotor so he could make the caliper brackets.
 

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IF they are Chevelle type discs, they are pushing your wheels out on each side...Which does not help tire/wheel clearance a bit.

From another thread:

Here is what I can tell you and you can make the choice.

The "entry level" system for a stock spindle uses a 69-72 Chevelle rotor or its equivalent. It's 11" diameter and it pushes the wheels out about 7/8", which creates tire to fender rubbing issues on a lowered car.

A step up for a stock spindle is a "zero offset" conversion, which doesn't push the wheels out (much). It uses a custom hub and a 79 TransAm rear rotor, 11".

With lowering springs, especially if you go too far, you may see the suspension bottom out on rough roads, driveways, etc.

The "entry level" brake package on most dropped spindles uses a 10.5" "Metric" rotor and a smaller caliper. Most push the wheel out 5/16" - 3/8" and that will work with the right wheel backspacing.

Dropped spindles will have full travel if you use stock springs, so the ride will be better on the rough roads.

There are many other combinations available, like bigger brakes, narrow track width etc.
 

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I'm hoping someone has the same front end setup as mine! I want to put different wheels on and the fronts are rubbing now that it's lowered. Here are the specs:

- Earle Williams 2" drop spindles
- Chevelle disc brakes
- tubular upper arms with +5
- power steering, not sure what box it is?
- 60.65" from mounting surface to mounting surface

Is anyone else running this setup? If so, what backspace do you have? I'm looking at either 17x8" with a 215/55 tire or an 18x8" with a 225/50 tire. Tire calculator says 5.25 to 5.5" backspace will work but was hoping somebody has this on their car already and can tell me it works with no rubbing. Thanks in advance!!
You should be good with the 5.25" backspace but if you want to be safe go with the 5.5". You can always add a spacer if the wheel is to far in. Worst case you would need to install longer wheel studs with the spacers. If your wheels don't have enough backspace not much you can do. Another thing that would help would be to add longer upper ball joints which helps your handling by giving you better negative camber gain on bump which moves the top of the outside tire in on a turn so you would get better clearance to the fender also.
I see your just a couple of hours away from me. I do have wheels & tires off of my 95 Trans Am that are 16 x 8 with approx. a 6 3/4" backspace. Tires are 245/55/16. Bolting one of those on would give a pretty good idea what you would need also. Weather sucks here right now but if you can wait a month or two you could come to my place to try them.
 

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Discussion Starter · #6 ·
You should be good with the 5.25" backspace but if you want to be safe go with the 5.5". You can always add a spacer if the wheel is to far in. Worst case you would need to install longer wheel studs with the spacers. If your wheels don't have enough backspace not much you can do. Another thing that would help would be to add longer upper ball joints which helps your handling by giving you better negative camber gain on bump which moves the top of the outside tire in on a turn so you would get better clearance to the fender also.
I see your just a couple of hours away from me. I do have wheels & tires off of my 95 Trans Am that are 16 x 8 with approx. a 6 3/4" backspace. Tires are 245/55/16. Bolting one of those on would give a pretty good idea what you would need also. Weather sucks here right now but if you can wait a month or two you could come to my place to try them.
Thanks Brian, that's very nice of you to offer!! I think that would be way too wide of tire and to much backspacing for my application according to all of the research I've done and the info I found? I was hoping somebody on here had the same setup and could verify for sure. Once tires are mounted on the wheels, I own them! I'm going to check around my hometown to see if I can find someone that has a wheel and tire combo close to what I need and bolt them on and try them?
 

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Thanks Brian, that's very nice of you to offer!! I think that would be way too wide of tire and to much backspacing for my application according to all of the research I've done and the info I found? I was hoping somebody on here had the same setup and could verify for sure. Once tires are mounted on the wheels, I own them! I'm going to check around my hometown to see if I can find someone that has a wheel and tire combo close to what I need and bolt them on and try them?
I know what your going through. We dealt with the same problem when my son ordered custom wheels for his 59 Mercury from Bon Speed. Being custom wheels at over $500. each we wanted to get the backspace right. We actually used my Trans Am wheels and tires with a wood block taped to the back to get a good visual on what the backspace should be. We came up with needing a 4.5" backspace so to be safe he ordered them with a 5" backspace which turned out to be pretty close. He probably would have been fine with the 4.5" or 4.75" but they look good at 5" and does not have rubbing issues on the inside or outside.



P.S. they are 10" wheels on the back with 285 and 8" wheels on the front with 245 on the front 18" dia on both ends.
 

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Are your rotors one piece like a 72 Chevelle rotor or are they two piece with a hub and a separate hat style rotor?

You need to be thinking about a 7" rim instead of 8". And 7" is more like the right width for a 215 tire.

You might pose your question to Earle since he now knows far more about your rotors (and his own spindles) than we do.
 

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Discussion Starter · #9 ·
Are your rotors one piece like a 72 Chevelle rotor or are they two piece with a hub and a separate hat style rotor?

You need to be thinking about a 7" rim instead of 8". And 7" is more like the right width for a 215 tire.

You might pose your question to Earle since he now knows far more about your rotors (and his own spindles) than we do.
It's a one piece rotor. Coys wheels makes a 18x8" with a 5.5 backspace that I would run a 225/50-18 on the front. Tire Rack says 7.5" max width for 215/55-17 and Discount Tire says 8" max width for the same tire? So, who's correct?!? Has anyone used the Percy's wheel measuring tool that Summit Racing sells for $70 bucks? It doesn't have the best reviews on their site but some people said they got it to work. Maybe worth a shot??
 

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How 'bout a pic of your disc brake and dropped spindles set-up?

I'm curious to see what it looks like.
 

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Coys wheels makes a 18x8" with a 5.5 backspace that I would run a 225/50-18 on the front. Tire Rack says 7.5" max width for 215/55-17 and Discount Tire says 8" max width for the same tire? So, who's correct?!?
So what do they say is the "recommended width" rather than the "maximum width? Seems like 7" might be it.

I can tell you this. There are lots of cars out there with 225 tires (10mm bigger than yours) on 7" rims.
 

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Discussion Starter · #13 ·
So what do they say is the "recommended width" rather than the "maximum width? Seems like 7" might be it.

I can tell you this. There are lots of cars out there with 225 tires (10mm bigger than yours) on 7" rims.
They don't give a "recommended width" or a "maximum width". They both give a "rim width range". For a 215/55-17 tire, Tire Rack says 6"-7.5" and Discount Tire 5.5"-8.0" for the same tire. I would like to stay with "off the shelf" wheels and I cant find a 7" wheel with the backspacing I need with out having them made at 3x the cost. I did find an 8" I like with the backspacing I need. I found 5.5" backspace is not common.
 

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Another factor here.

The wider the wheel, the more backspacing you'll need for clearance to the outer sheet metal.
 

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Either of the tire sizes you are considering will work with an 8" rim. It the widest you would want with those sizes but it will work. I have 255/40/17 on the front of my 55 on 9.5" Corvette wheels and they work fine. (widest rim for that tire size) The guy who mounted them said they were more of a challenge to get the bead to seat because of the wider rim though. If you look at the thread in my signature there should be pictures of them mounted on the rims before and after being on my car. (page 4, post 40)

Rick, I think the 5.25" to 5.5" backspace is what is needed with an 8" rim.
 

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Discussion Starter · #18 ·
Well.....I found a guy that had a set of Camaro wheels off of a '92 that had 5.25" backspacing on a 16x8" with a 225/60-16 tire mounted to it. Right on the edge of where I need to be but worked well with lots of room inside, no rubbing. Still a little close to the fender lip so 5.5" should be perfect! Thanks to all that responded! It's so much nicer to actually bolt something on that you can turn and spin than wrestling with a tape measure and straight edge!
 
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