Front toe settings have been discussed at great length in this forum but I've found that most discussions focus on the effect on tire wear and only general comments on handling. There's general consensus that toe-out "helps the car turn in" but I could not find much more objective comments on effect on understeer/oversteer in different dynamic situations, not just "turn-in". I've just put my winter set of tires back on and took the opportunity to explore the car's handling characteristics at the limit back-to-back before and after zeroing front toe (I was running -1/16" total toe out on my summer set). FWIW I wanted to share my observations as I found them very useful and informative. For reference, current setup on my 2011 is OEM suspension with RR Racing USRS and F-sport rear sway bar. My winter tires are Michelin Alpin PA4 245/35/19 front, 255/35/19 rear. I did my little test at a very large vacant parking lot at the local ski resort in cold and wet conditions that allowed for easy loss of traction at relatively safe speeds without much risk of sending it off the embankment. I did 2 tests, with VDIM off of course:
1) a version of a skid pad test driving in a constant circle in 2nd gear, accelerating as gently as possible until loss of traction,
2) emergency lane change maneuver (like moose test) at 90 km/h (56 mph) to try and induce oversteer. I kept maintenance throttle to not upset front-rear weight distribution.
What I've found:
With -1/16" total toe out the car balance is very neutral on skid pad steady-state cornering limit and it is very easy to induce oversteer with a bit more throttle, however very progressive and controllable. It was relatively easy to induce some oversteer during moose test maneuver but easily controlled with a little counter-steer.
With zero toe the car tended to push quite a bit past the limit on steady-state cornering. You could feel the front tires scrubbing and kind of skipping if pushed harder. It required a lot more throttle to overcome the understeer and get the rear to step out and it was not a very controlled feeling. The moose test still felt good and controlled and it was very hard to induce oversteer no matter how hard I tried.
I wanted to share this because a lot of us complain about the ISF tendency to understeer and most people look to increasing rear roll stiffness and getting wider front tires which are of course effective as well but seems toe alignment is overlooked or at least not given nearly as much consideration as another tool for dialing out understeer.
Below is my last 2 alignment settings.
Toe out increases front traction on turn in and reduces understeer. Lexus designs a whole bunch of things into the geometry to invoke understeer, not just toe. I run close to 1/8" (3mm) toe out all the time because even with 255s on front and 275s in the back, the car is more stable on turn in, and it's easier to induce throttle oversteer with the nannies turned off. I have not changed the sway bars from stock and my ride height is also stock. Lowering will change this because you'll be using a different point in the camber curve when at neutral.
I did 2 tests, with VDIM off of course:
