I have been tinkering with this for a little while. You can, but it is not perfect. Like Ray says, if the tracks are too different in their setup, the order of the AI cars gets mixed up. Also, some tracks have AI that just needs slowing down or speeding up a little bit, while others tend to send cars flying through the infield or flip the whole field in turn 1. My methods only help the tracks where AI functions but needs a minor speed adjustment.
I look at the qualifying times first. If I ran the lap of my life with a perfect setup and I am in 48th by 3 seconds, I need to adjust the qualifying speed of the cars.
I go to the "Track" str file and look for AI lap times
I adjust "Best sim mean", and "worst sim mean" up or down a bit. The best sim mean will speed up or slow down the front runners. The worst will adjust the back cars in the pack. These change the lap times during qualification and the times during the races you are not running, but they don't seem to influence the speeds of the cars that you run with during the simulation. I am just experimenting with adjusting the standard deviations (Std dev) to adjust the differences between the fast and slow laps of the individual cars. I can't really discuss how they work reliably yet, so I will just say that I made copies of a few tracks, put together a small series with them and I am learning by tinkering and tweaking. The arcade means right below them seem to change the speeds in the single race mode instead of career mode.
Now that the cars qualify at a reasonable speed, it is time to adjust the way they race.
I have been using the race difficulty settings under the AI lap times to adjust this. I have not sorted out the exact results of the Pure, Prod and race difficulties yet, although pure seems to do more with lap times while you are racing, and race seems to adjust to what the player is doing a bit more. I haven't really figured out the exact differences, but I have been able to make some decent adjustments to speed up or slow down AIs to make all of the tracks in a series run similarly.
I just lower all three numbers (Race difficulty, pure difficulty and prod difficulty) a bit to slow down the AI, and raise them to speed up the AI. As I experiment with them, I will report back as to what they do. individually.
The arcade difficulties right below them seem to affect the single race settings instead of the career mode.
I know this isn't as much help as you would like, but this is what I discovered by diving in and tinkering with it. There is not much information out there, and I couldn't find a tutorial on it, so I just jumped in and made changes and looked at the results. I made a copy of my tracks folder, and set up a small late model series with eight ore nine tracks and tried to equalize them all. Also in the series str file, you can adjust the difficulty of the whole series up or down a bit. That can come in handy if you are making a beginner's series and a national series with the same class of cars and want the big series to be more competitive than the local series. Also this helps when you have different series for different classes of cars, as some types of cars need a bit more or less difficulty than others.
Good Luck, and back up things before you start tweaking. (Don't ask me how I know this)
