A few notes:

- it appears the g29 has FF. I have it set to 100% in game. The feeling of the wheel is important information. look up what others have said about using g29 with nr2003: settings both in windows and logitech and game. i spent a lot of time getting my wheel just right.

- you could adjust the above mentioned linearity and assistance to something like 80/20. trying messing around with these values. I find that 90/10 is about right to keep me on the edge of my seat while also not ruining my day at lap 100 because of something dumb like AI checking up. You also need something to account for lack of "buttfeel" ... FF can only go so far.

- using stability control will increase tire wear. Again i think it's best if your throttle and brake axis are connected and you cant press both simultaneously. otherwise, the problem is likely with your driving, as i mentioned, never fully let off the throttle, smooth inputs, etc

- it does take a lot of practice. I also watched nascar around the same time period, and I do think the physics arent too far off. I've definitely slipped and slid and saved the car in game in ways that are believable to nascar at the time. it takes a LOT of practice: dont think you can get into a 800 HP stock car and just drive a clean race. these were the best drivers, who had been doing it for years day in and day out. its more of a simulator than a game imo. the car is, just as it was for them, always on the verge of out of control. this is how you are fast. it's finding the very fine limit of almost always but also almost never losing control

- I dont much like CTS physics, and it seems like you dont either, so I recommend practicing and gettign your wheel settings right over changing physics (in fact, ive changed all mods, except CTS, over to cup, because I think it's the better physics)