Wider Wheels = more negative camber?

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HappyIdiot
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Wider Wheels = more negative camber?

Post by HappyIdiot »

I have an odd/newb question, that I haven't been able to confirm. I went for an alignment yesterday and was a little surprised by my initial numbers. The last time I had an alignment I was on stock 16" wheels with 205/55/16 tires.

-1.5 -1.5
-.8 -.9

I wanted to get a little bit more negative camber out of the front this time. I remember from last time that the rear was maxed out.

My initial numbers yesterday were

-1.7 -1.5
-1.1 -1.0

Somehow I gained negative camber on three corners. Between then and now, I did swap to a 17x7.5 wheel and 215/45/17 tires. In my head, if I think of the hub as a fulcrum, the angle of the hub probably didn't change that much, but the lever arm, width of the tire/wheel, became longer. Is that correct thinking? Second, does the width of the tire or wheel have the impact? So, if i I was to go to a 225/45/17, would the negative camber increase, or is it an effect of the wheel width?

Final numbers were

-1.9 -1.9
-1.1 -1.1

0 toe all the way around

Thanks!
My Name is Adam.
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drwrx
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Re: Wider Wheels = more negative camber?

Post by drwrx »

Lowered wagon set-ups usually have a lot of negative camber in the rear, -1.5 is common. Going with the wider tires means more negative camber is usually the way to go. Less chance of fender rubbing.
This looks to be very close to what my set-up was on my 02 wagon. 215/40/17.
No, I suspect 225 width tires would't affect your camber.
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zaxrex
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Re: Wider Wheels = more negative camber?

Post by zaxrex »

I read his question as if he were asking if the wider wheel/tire would cause the suspension geometry to change resulting in the lower camber reading.
If that were the question then my answer would depend on how the camber was measured and what the offset and hub center thickness of the new wheel was.
Adam, did you put in camber bolts, or are you using stock ones? If the stock ones, then all they do is pinch the hub in a set position and can wiggle about after time and go negative on you.
Assuming you had actual camber bolts that provided a lobe to lock hub movement... then read on as to what I think.
If they were using distance measurement from a vertical plane through hub face, then yes, a wider wheel with a different offset could give a more pronounced camber reading as compared to the original setup. But this measurement method is less accurate since the distances have to be measured from a reference point that may move from reading to reading.
If the measurement was done by pure angle of the wheel (or better yet, from the hub with laser reflector readings) then the difference in camber, if any, should not be measurable since there are no wheels on the car.
That being said, I had an alignment done at PTuning and before they last measurement was recorded, the guy tripped over the power cord and unplugged the system. The first three readings were recorded, but to get the the fourth, he had to go through the whole process again. When he was all done the second time, the reqadings had changed 1-2 tenths from before. Nothing had changed in the suspension geometry and the car hadn't moved.
So between measurement accuracy, how much weight difference the car had, temperature of the springs... I could see 2-3/10ths of reading difference. Any more than that, I would think like you and that the geometry is changing where it shouldn't be. Even if you didn't change the offset of the wheel and the whole width increase was outside the wheel hub, a handful of ft/lbs difference should not change the suspension geometry.

There that should have muddied the water up a bit...
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drwrx
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Re: Wider Wheels = more negative camber?

Post by drwrx »

Sorry, yes I totally misread the question.
I'm not certain if the camber can increase with a larger tire, but that, combined with the wheel offset may be possible.
The offset for the 16" 2002-04 WRX wheels are +53mm. (53mm away from the center of the hub toward the outside of the wheel.)
The offset for the 17" x 7.5" Rota Grids are +48mm.
While 5mm less than stock, the extra 1" of wheel width along with the extra tire width may be difference but I suspect the camber bolts were adjusted to get the extra negative camber.
As to going to 225s . . . Honestly, the tread widths between most 215 and 225 tires are pretty mild (7.6/7.7" vs 8.0/8.1") so under half an inch while the 205 run around 6.5" wide.
If you feel like going to 225 width tires you probably can do so w/o fear of impacting your camber. The extra .5" diameter might make the difference in rubbing the fender wells though.
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Re: Wider Wheels = more negative camber?

Post by HappyIdiot »

Thank you for the responses. The stock camber bolts are in the rear and there are additional camber bolts in the front. I think maxed out at like -1 degree with the stock camber bolts in the front, when I had the previous alignment done. They put in new camber bolts to get to -1.5. I'm not sure what the max is for the front with those bolts. The guy behind the counter thought it was about -2 degrees. The alignment was done both times at PTuning, which they attach the devices to the wheel faces. The offset numbers make a lot of sense with effect on the camber.

As to the 225s. It is more of a convenience thing, which sounds really weird to say. Anna still has her stock 225 summers in the basement with about 3,000 miles on them, no wheels though. I was thinking about/planning on stealing those. I ran her 225/45/17 winters two winters ago and I couldn't tell if I had any rubbing. I assume I would hear something, although I wasn't really pushing the car hard around turns or putting a bunch of weight in the trunk. Maybe, I'll borrow her current 225's and try them out, unless you think it isn't really worth it. It would be nice to be able to share tires between the two. So, as she is done with a set, I can still get a season of auto-xing out of them.

Thanks for the responses!
My Name is Adam.
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drwrx
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Re: Wider Wheels = more negative camber?

Post by drwrx »

I suspect you are safe with 225/45/17s.
You could inquire how Zak is doing with 225s on his silver wagon.
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Re: Wider Wheels = more negative camber?

Post by HappyIdiot »

Sweet. Thanks. Out of curiosity, what alignment specs did you run?
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drwrx
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Re: Wider Wheels = more negative camber?

Post by drwrx »

I can't recall exactly (it was over 10 years ago), but it was around -2 front and -1.2 rear with 0 toe.
That with the 22mm rear sway really improved the oversteer "ability" of the car. It was never tail happy, but it drastically reduced it's tendency to plow.
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Re: Wider Wheels = more negative camber?

Post by HappyIdiot »

Yeah that is really similar. I have the 22 mm in the front and rear and I'm really happy with them. The rear with the strut bar made the biggest improvements in my book.
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zaxrex
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Re: Wider Wheels = more negative camber?

Post by zaxrex »

The numbers on tires lie.
I replaced the tires on the original Rotas with my Blizzaks. Same 225/45/17 numbers on the tire, but the winter ones do rub on the left corner. Put a +53 offset and Fusion ZRi's at 225/45/17 and no rubbing.
Go figure.
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drwrx
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Re: Wider Wheels = more negative camber?

Post by drwrx »

zaxrex wrote:The numbers on tires lie.
Not exactly, the numbers are not really meant to be exact. The aspect ratio in particular is a very "fuzzy" number as a percentage of the section width to the sidewall height.
But yes, the width and diameter on tires of the "same size" will vary, often dramatically.
Snow tires are nearly always narrower and taller than their similar "sized" summer or all-season brothers.
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Re: Wider Wheels = more negative camber?

Post by Sabre »

Along those lines, with my winter tires on, I can easily get the jack under the jacking point on my STI... with my summers on, which "are the same size" it takes some wiggle. This is when both sets were brand new, so they should have been the same.

BTW, I run whiteline sways all around with -2F -1R and love the setup. Very neutral with a hint of understeer at the limit.
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Good choice putting $4,000 rims on your 1990 Honda Civic. That's like Betty White going out and getting her tits done.
HappyIdiot
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Re: Wider Wheels = more negative camber?

Post by HappyIdiot »

It really just sounds like a crapshoot. I'm going to try Anna's this weekend and see what happens. It isn't quite apples to apples though. Her's are 17x7 ET45. Using the wheel offset calculator, it will be about 3mm more inward from the fender than the Rotas.

Thank you for all the info.
My Name is Adam.
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Re: Wider Wheels = more negative camber?

Post by HappyIdiot »

I tried Anna's wheels and I rubbed. No big surprise. Oh well. It was worth a shot.
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drwrx
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Re: Wider Wheels = more negative camber?

Post by drwrx »

Sorry to hear it.
If you want to have swappable wheels you may have to roll your fenders.
I can't recall if someone had a Delrin ball. Probably worth a call out on here or NASIOC.
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Re: Wider Wheels = more negative camber?

Post by HappyIdiot »

Nah, not worth it. I'll stick with the 215's. Thank you everyone for your help!
My Name is Adam.
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