Tire Pressure: Tire pressure is measured in PSI, or pounds/ square inch. The higher the temperature, the greater the PSI will be for the wheel. If you put your wheel on 30 PSI, and then do some drifting or burnouts, you will notice that the PSI is now higher, since the wheels heated up. You always should adjust you PSI settings lower than what you want, so when you are racing, it will reach your goal PSI. Grip and handling are also affected by PSI.
Gearbox: The gearbox is the most customizable part of your car. It has a Final Drive, along with each gear ratio. The Final Drive controls all of the other gears, so if you adjust that, it will adjust all the other gears as well. The individual gear settings are great, especially if your gears are too long, too short, you want more torque, you want more top speed, etc…. However, there is always a butterzone for each car, where the gearbox will perform its best. Using the benchmark, this can be attained by just playing around.
Suspension: This is also a very difficult piece of your car to play around with. If you have a soft suspension, your car might oversteer, but overall reaction will be very off. Stiff suspension is great for hard-end racing, but make sure you don’t bottom out on a big drop.
Tire Caliber: This adjust the angle of your wheels in congruence to the car’s body. If it is too positive, you will have a hard time on straights, and will have massive oversteer. Opposite for negative. Once again, you have to find the butterzone.
Ride Height: Pretty much same as suspension rules. If it is too low, you might bottom out. I always lower it to the max, just because it looks cool.
Brake Pressure: If you use ABS, just skip this. I like to race at 200% brake pressure. I know it sounds crazy, especially since I don’t use ABS. However, I have become very adept to using my settings, but you need to do what works for you. There is really no rule for brake pressure. The higher the pressure, the faster you stop, but also, could lock up the wheels faster.
Downforce: Three words: Dodge Viper ACR. This car has massive downforce. Of course, not as much as others, but still is a lot. If you have the aftermarket wing(s) installed, you can adjust how much downforce your car makes. Too much downforce, and your top end speed with be greatly affected. However, with more downforce, comes better handling.
Differential: It is really helpful only on AWD cars. FWD and RWD cars don’t really get affected by it. If your AWD car is understeering, increase torque to back wheels. Pretty much it for this.
Sway bars: These bars help prevent, well, swaying. If equipped, they will increase stiffness of suspension, but help make sure the car doesn’t spin out when going over a hard turn. Although the decrease the PI or your car, I see no reason why not to have them, unless you are a drifter.
Well, that is it for now. I probably forgot something, as I did these from memory, and not looking at the tuning screen. Let me know if you want to add anything to this! I really hope this helps those understand tuning.