I read an interesting tidbit researching real life suspension tuning from a website I can no longer remember. On this site, they mentioned something about rear toe I had not seen mentioned in any Forza tuning guide or advice on any Forza forum I had checked out.
The site mentioned that under acceleration, the rear tires naturally Toe Out. Toe In on the rear tires could be used to insure full even traction under acceleration. I found it interesting and wonder if it applied to the game. So I went into Daytona with an untuned car. I made sure the rear tire camber was at 0, and used the tire temperature telemetry to see what happened under acceleration. And there is was. Under straight line acceleration, the outside of the rear tires heated up as if they were toe’d out. I raised the toe-in until the tires heated evenly under acceleration.
I tested this on a bunch of my favorite cars and I noticed much more stable rear tires while cornering, especially under acceleration. So it is now one the first things I set when I tune, especially before any negative camber. I went back and tested it on the Dodge Superbee, which I had given up on due to funky handling, and had to go all the way to -.4 toe to get the tires to heat evenly under acceleration. I noticed an immediate rear end handling improvement though and am now having fun doing time trials in C Class with it.
I am not the greatest tuner, but I hadn’t seen this tidbit here or in any game specific tuning guide and thought I would share.