Originally Posted by
mr shickadance
a inch stagger is nothing crazy, if you think that cars come with this surgical precision built into for which if you modify in any manner the car is going to implode on you then your idea off how cars are built is far off.
These cars a built with certain tolerances, and if you exceed them, yes, you will have problems, but these tolerances are not precision-driven, there are limits, and going 1 inch wider in the rear is not even scraping the surface of the limits.
running a staggerred set up is a debate that carries one as long as aftermarket wheels and AWD cars have been popular. there are a bunch of a opinions, and not a lot off facts, and sometimes opinions are so widely spread that people view them as facts, but that still does not mean its right.
yes, a square set up compared to the a staggered will have an upper hand, slightly, very slightly, so slightly that the differences made could be attributed to a million other things not kept constant, that's how slight of a difference we are talking about here.
so you can certainly share you viewpoints, but ensure that they are accurate, and represent both sides of the story, running staggered has a stigma attached to it that it's the worst thing in the world and it's just not true.
honestly, what fancy suspension geometry do you think is involved here? if anything, the center, F and R diffs would have more of an impact and more likely to be 'special'
The mathematical definition of understeer/oversteer deals with the relative slip angles of the front and rear tires while attempting to steer the car relative to ackerman. This will change a lot depending on the dynamic state of the vehicle, I think most people here are concerned with aggressive driving or track driving, not getting groceries.
If you run a setup like 265/295, then in a simplified sense, you have increased the rear contact patch area by a relative 30mm / 265mm = 11%. Now we're talking about a car that has driven front wheels (AWD), so when driving the car near the limits under power (such as on a track cornering), you have already traction limited lateral grip on the front wheels due to AWD (increased slip angle now - def of understeer), and have reduced the slip angle of the rear tire by increasing the contact patch by 10%. The tire physics are being over simplified and don't obey simple linear relationships, however, you are clearly preventing relative rotation of the back-end, much more so than your hypothesized 1%. AWD cars generally don't need as much understeer help from the suspension since they already do it naturally based on the drive line.
Wrote up this little cartoon, should make sense, you can see the larger tire has more grip, thus less slip angle (psi), thus less ability to "swing" around like a neutral steer vehicle would. Left side is square setup (just two tires, front and rear like a bicycle) right side is with larger rear tire. Trying to corner to the right, assuming same slip angle on front tire in both cases.
A 911 or any RWD is a completely different vehicle, since you can change the rear slip angle by simply using your right foot -> reducing rear lateral grip -> oversteer. Those cars need staggered tires both for straight line acceleration in low gear, and all the natural understeer they can get under throttle to prevent one from wrapping them around a tree.
I agree that factory alignment is designed to make the car more predictable and less responsive, and changing things can make the car handle much better (not just changing oversteer/understeer though). Sometimes to the detriment of tire wear, but this is a whole other discussion. But I wouldn't argue that tire staggering has a negligible effect on handling. I think the problem is that everyone wants to understand things through a black/white lens: "coilovers are better than springs?" "the S4 understeers while the 335 doesn't" etc, just vast oversimplifications of pretty complex topics.
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