Would that be because of the car used, the track, whether weather was chosen, the tires used, tire wear rate, etc?
Could be a lot of variables open still.
My experience with this problem, has been solely on Race Hard tires, and from what I've read, it's more prominent on racing tires. I think it's possibly just more noticeable on race tires, because you start out with some pretty good grip, so when you lose some, even just a little, you notice it. During my tests of this, I was running the Honda HSV base race car, at Apricot hill. The car starts out fairly tight, but after a pit stop, it is noticeably less tight. Now the change is not so drastic, that I'm hanging the rear out, but there's definitely less effort on turn in. On top of that, the rear tires wear out much quicker, than the original set.
I've repeated this with the same car, at the same track, on multiple occassions, with the same results each time. Before and after update 1.03, so the bug has been here a while.
Today I've run the S class 10 lap thingy at Silverstone. I have to pit after five laps because I run out of gas on the sixth lap. When I pit after five laps, I've got plenty of rear tire, but the fronts are worn. Rears at 6 and fronts down to 4 on racing mediums. Lap times up to the pit are 2:01 with a 2:06 on the fifth due to the push of the worn out fronts.
After I pit and keep the racing mediums on, my lap times remain 2:01 until the back tires start to go. The car is a death trap on the final half and the first race I fell from 2rd place to 10nd in the final two turns because the car was uncontrollable.
The same thing happened on a different car. Same lap times, completely different tire results before and after the pit. To clear this race, I'm going to need a different car, the Corvettes have too much engine.
As far as I'm concerned, this is the biggest issue facing PD. The tire noise is one thing, the shitty shadows are another, but both pale in comparison to a completely fucked up tire bug. I remained dumbfounded how this game was released in this condition.