I think I just did a tune from the forum, but I adjusted it slightly, I'm new, only been playing for four months, and I don't even really understand cars too much, I just like games, but I noticed a couple of time trials ago it was the Ferrari f1 at Monaco, that the toe was at something like minus 55 on the front, and plus 55 on the rear, and that thing could turn great, so now once I get what I think is my best time, I adjust the toe of whatever car I use to that same placement, and I have always got a better time, probably took off a second each time, I'm not really sure why, or what it does specifically, but it works for me, try it.
I used the Praiano tune (the man!) for the MP4 12c on the F1 94 accidentally, the gear ratios wouldn't work out, but when it hit the track, wow, very stable and a 2:08 gold in one lap. The trick seems to be extreme toe in f & r. added some aero wings and cut some weight to get a bit better.
Funny thing was when you drive the Practice area GV R the exact same car is 5 sec faster and even more steady.