Arek

Hi,
I just installed 17" CSX wheels on my '04 TSX two days ago. I believe they're the same as the HFP wheels for a Civic Si. They're the same size, 17 x 7, but with an offset of +45.
And that's where I think I may have a problem, and wanted to consult you guys, as I don't really tinker with my car and my knowledge on the suspension issues is limited.
I like the look of the wheels (and new tires - Potenzas RE760s) on the car, and the way it quieted the ride, and maybe even added to the comfort a bit, but... I never expected that the 10mm difference in the offset would be so visible! To my (untrained) eye, the fronts are flush with the fenders, which I guess is ok, but the rears - seem to have negative camber now! I think that the only reason for that can be that the additional leverage that the lower offset puts on the suspension, caused it to drop slightly? Does it make sense? Although, from the side I don't notice any difference in the height.
I'm thinking that the stock 215 tire contributes to this more than a wider tire would, as it would extend further inside and sit where a stock tire/stock +55 wheel normally would put it?

Anyway, my point and the question is this: is the extra leverage of 45+ offset going to cause my stock suspension to blow (about 97k miles on it)? Kind of like throwing just lowering springs on, which I've read about here?
Not to mention, I'm not crazy about the uneven and accelerated tire wear it will cause.
Is it possible that my suspension is affected by this more because of my mileage, and it's on the way out anyway?

I'm really worried that I'm going to blow my shocks soon...

SG81

iTrader: (1)

you won't blow your shocks b/c of that offset difference. heck, i'v been lowered on lowering springs on my OEM shocks for 5 years now and they're still good

Simba91102

The difference really is minor, especially on a stock suspension (and there's no difference in net negative camber just because the wheels have less offset). The different look is probably more noticeable because you're so used to looking at the car with the OE wheels. And you shouldn't have to worry about suspension or tire wear.

Arek

Thanks SG81 and Simba for your inputs...

I know it doesn't make sense, and just a different wheel should not affect it, but it's there. That's why I thought that maybe the wheels sticking out more put more leverage on suspension and it sits lower.
I have a pic showing it, but I don't think I'm able to post pics yet?

Itchytoe

Your car likely had more camber than you thought before you swapped wheels, but you're noticing it now because you're looking for differences. When I looked at mine, I noticed they had a bit of camber to them with a completely stock set up.

feuss2

iTrader: (1)

The decrease in offset increases the track which should improve handling because the roll center is lowered. This is claimed by people who have installed wheel spacers, which makes a comparable change.


The suspension levers are longer, making your effective spring rate lower (this softens the ride). Since the sprung weight of the car has not changed, it should sit just a little bit lower. This will also make the camber more negative all the way around.


All these changes will be very slight, since the track and the ratio of track to wheel base have not changed significantly. It's unlikely that the camber has changed beyond the acceptable range either.


The rear camber is supposed to be negative. The lower offset could exaggerate this because the wheel is closer to surfaces you can use as a reference point.

Arek

That's exactly what I was thinking.
Good point on the visual effect that the new setup might have exaggerating the amount of actual camber.

Simba91102

I don't agree with your theory. The camber (which you are right about. The OE spec is -.5 to -1.5, ideally -1)(which isn't adjustable by the way) is a suspension setting and no amount of positive or negative offset will change that, assuming no parts of the suspension have been changed. Draw a right angle, only tilt the vertical line in slightly to indicate a negative camber. Now draw a line out from the base of the right angle (signifying the hub centerline). Now draw a vertical line through that line at various points to indicate offset. You can see that no matter where you draw the offset line, the net camber stays the same. You are moving the wheel "center" which magnifies the load on the hub (or "wheel") bearings, but it should be minimal.

feuss2

iTrader: (1)

Your example either does not account for ride height change or assumes constant camber if ride height is changed.

The wheel moves along an arc as the suspension components are compressed and the camber gets more negative. This is why it is necessary to correct camber after installing lowering springs. Increasing the sprung weight of the car would also compress the springs and decrease the ride height.

In this example, the wheel width stayed the same and the offset was reduced, so the increase in the lever length is equal to the offset. The same sprung mass will compress the springs just a little more than before.

Simba91102

If I read the last part of your post right, you're considering the wheel to be sprung weight. Not so.... everything below the spring (which includes the suspension and..... wait for it.... the wheel) is unsprung weight (this is why you can actually feel the difference when lighter weight wheels are installed and why the TSX has some aluminum suspension components and the Hyundai Sonata uses all stamped steel pieces).

It may be true that the mechanical advantage changes slightly with less offset, and this may impact stress on some components (based solely on comparing the change to the OE wheel). But, since the suspension geometry hasn't changed (because no parts of the suspension have changed) I still don't see where this has the same effect as using a lowering spring. Since all you're really doing is changing the wheel "center", the wheel (and everything below the spring) will remain on the same plane as before regardless of offset.

feuss2

iTrader: (1)

Where did you get that from? I am describing various situations where you can see camber getting more negative.

• Install lowering springs, camber gets more negative
• Increase the sprung weight - for example put some heavy junk in the trunk. The car will sit lower, the camber will get more negative.
• Install wheels with a lower offset. The added leverage will cause the suspension to be compressed slightly more than it was with the higher offset. This is because the effective spring rate is lower.

This literally means:

• you can actually feel the difference when lighter weight wheels are installed because everything below the spring is unsprung weight
• the TSX has some aluminum suspension components because everything below the spring is unsprung weight
• the Hyundai Sonata uses all stamped steel pieces because everything below the spring is unsprung weight

What is this trying to explain/prove?

Mechanical advantage increases as the distance from the pivot point in the suspension to the outside of the wheel increases. In this example, both wheels are the same width, so the change in offset = change in overall lever length. The effect would be even greater if the wheel width also increased.

A change in offset is a change in suspension geometry. It changes the track, and usually results in a handling improvement. The differences would be the same as if the stock wheels were used with 10mm spacers.