18x9.5 +22 on FRONT and rear..

[SmartBastard]

Originally Posted by Finnegan

[*]A wider wheel with the same offset as stock will not change the scrub radius (assuming the tire's sidewall height stays very close to stock as well). This limits how wide you can go and retain clearance. With stock offsets, camber plates are a viable option to increase negative camber and clearance from the strut, since there's no need to dial the scrub radius back into spec.[/LIST]

• Asking what others are running needs to take into account other suspension modifications they have (lowering, camber bolts, camber plates, caster, wheel height, tire sidewall height, tire type since sidewall flex can affect scrub radius as well).

Bottom Line: There's a hell of a lot going on with a lot of variables involved. If you're going to mess with this, do the math!

That's what I though, I would like HACK to confirm on this
Yes, I have read those articles plus some wikipedia stuff, but I'm very far from understanding the whole thing.

[Finnegan]

Originally Posted by SmartBastard

That's what I though, I would like HACK to confirm on this
Yes, I have read those articles plus some wikipedia stuff, but I'm very far from understanding the whole thing.

Thanks. I don't understand the whole thing either, but I now understand enough now to know that changing the offsets is a lot more than cosmetic or "stance" related. It profoundly affects suspension geometry. Ultimately I'm interested in how the car performs/handles, so it matters a lot to me.

[marlingator]

Based upon all the information in this thread, if i were to put a 12mm spacer on my front stock rims it would degrade the handling of the car ? Am i understanding this correctly?

[Finnegan]

Originally Posted by marlingator

Based upon all the information in this thread, if i were to put a 12mm spacer on my front stock rims it would degrade the handling of the car ? Am i understanding this correctly?

Generally speaking, yes, you've got it. Pushing out the wheels with the spacer is pushing out the scrub radius from negative into neutral or positive, which isn't good with a McStrut suspension. If you've made other changes to the suspension, e.g. camber washers, lowering, etc., that could neutralize or mitigate the impact to some degree.

[tikamak]

Originally Posted by The HACK

The issue here is directly related to the wheels that steer a car, so unless it's a 4 wheel steering vehicle, steering angle inclination and scrub radius has little to do with the rear wheels.

In general, what I am saying is measure, test, and adjust. The issue with camber bolt is that it brings the top of the wheel/tire closer to the strut and you lose clearance, so there are cases where camber bolts aren't ideal, especially if you intend to run super wide tires up front.

So the real problem with tinkering with the front suspension is, it's all inter-related. If you add camber bolts, you may want to alter the offset to allow more clearance inside, but by doing so you may potentially increase the scrub radius enough to impact steering and grip up front.

Ultimately, the added grip with wider tires up front may trump the smaller effect of poor scrub radius and allow you to go faster. That's why I always say, suspension tuning is a series of finding compromises. My current compromise seems to be 245/40/18 tires up front with -2.5 degrees of negative camber, slight (1/16 total) toe-out, with 2 washers on the camber bolt and ~stock-ish ride height, and factory off-set. This seems to work very well for me after about 20 days worth of tinkering on the track.

There's something i don't understand, wouldn't shimming the kingpin with the TMS camber bolt set drive the base of the tyre away from the steering axis to gain (negative) camber and effectively adding positive scrub radius?

Is it me understanding this whole thing upside down? Would you care for an explanation ? mspaint is welcomed :P

[The Shoe]

I run 18x9.5 et 22 fronts, and 18x10.5 et 22 rears. 245fr/275rr Michelin PSS Tires. Daily driver, lowered on H&R coilovers, only rub was front fender liner but that has stopped now after wear. But it was a good amount of work to get it to work. Need heaps of camber front and rear, so pulled pins and shim kit in front, turner rear LCA's and sway bar links. And a very very good alignment. I had 3 alignment sessions because I needed to get it just right.

Superb turn in response but if you set rear camber past 3deg, you will get camber hop past 120-130mph and its very unsettling. But it does great on Auto-X. I shouldn't be driving at those speeds anyway so it forces me to back off.

I don't recommend it unless you know what you are fully getting into. A lot of good info on this thread. That type of front offset with increased -camber will reduce your wheel bearing life among other things such as tire wear.

Would I do it again, YES!