It occurred to me that using high-offset wheels, that really stick out past the rear fenders, would require a stiffer rear sway bar to compensate, right? Or is the side leverage not applicable that way?

 

Yessir. Widening the track changes the roll center and drops it far below the car, adding more leverage and causing more bodyroll. Lowering does the same thing but the difference is usually negligable at or around 1" and the higher spring rates compensate so most spring companies advertise that lowering springs decrease body roll. There's nothing to compensate for the wheels so I'd imagine the difference is pretty dramatic. I don't have any hard evidence but this theory could be tested by throwing some spacers on stock wheels and playing around a parking lot and repeating without the spacers. If anyone does this some video would be nice

 

Theoretically, probably true; real-world, you could probably change the pressure in your tires by 1 psi, or add a ¼ tank of fuel, and produce an effect that would totally swamp the other.

 

?

 

Thanks guys. I got to wondering this, because if you were ONLY cruising the interstate, with NO cross winds, and the ONLY bumps were expansion strips that were exactly 90 degrees to the direction of travel, then changing the offset should have NO effect on the ride quality.
Thus, no effect on the effective spring rate under these forces.
But our cars were made for cornering, and the high offset moves the outer sidewall farther from the spring.
Now, if you compensated with spring rate, then that would make it ride worse when just cruising. So to keep the ride, but resist the roll, that must mean a stiffer sway bar.
If the outer sidewalls only moved an inch, then that may not call for much change to the bar. But if we moved them 5", then maybe a few more MM of bar diameter?
somewhere here on TGO, there's a black one with an aftermarket widebody kit. It reminds me of a Testarossa, but isn't any copy. It has 295/50R15 rear tires.
I'm not of a mind to do either of my Camaros like that, but that kit must add a good 4" to each side of the car.

 

Moving the center of the tire outward drops the roll center; to what extent and whether or not it would be noticeable from the seat of the pants or outside of the car is in question. Lowering a car with springs drops the roll center, but even cut springs compensate for this as their rates go up as you knock off coils. Unless you buy stiffer springs or bigger bars there's nothing to compensate for the drop in roll center caused by high offset or spaced out wheels, so it would be interesting to see just how big of a difference it really makes.

 

the way i look at the pics, if you move the wheel outward, leave the ride height where it is, the roll center goes up, slightly, not down. unless im a r-tard

 

Those are for the front. I'm interested in the rear. The panhard is supposed to determine the rear roll center, isn't it?

 

true, the rear roll center height is the center of the panhard, the wheels do not change this, doesnt matter where they are.

i see no way the width and location of the tire could change how the body of the car rolls, except a possible amount in the front, but even then, its a tiny amount

 

So you're looking at it like the axle is flat and the body is moving. I was looking at it like the body was staying flat and the axle was moving. I guess because the front end is heavier, has the bigger bar and the stiffer springs, and the front springs are closer to the outer edges of the tires.
So with the front determining what the car is doing, then the rear is all about the axle.
Our cars don't roll very much, anyway. Well, maybe the boring versions do, but not the best versions.

 

they dont roll nearly as much as a minivan or caprice wagon, but they do roll more than some people think they do.

 

Yeah now that I look at it again I'm pretty sure I goof'd.

 

its ok, everybody is allow to brain-fart every now and then