Faster Corner Entry Means Earlier Turn In
Published: October 30, 2013
Or, the higher your entry speed, the earlier you turn.
Note that an early turn in is not the same as an early apex. The apex remains the same.
Why does a higher entry speed necessitate an earlier turn in? Think about maneuvering in a parking lot. At 2 mph, your turning circle is much tighter than at 5 mph, and at 10 mph you probably won't be able to make a circle at all without running into something. If you want to fit into a 2 mph circle driving at 5 mph, you will need do use a lot more steering angle. More steering angle while going faster demands more grip from the tires. Trying to fit into a 2 mph circle while doing 10 mph will typically result in screeching understeer or donuts, depending on the car's power level.
The same concepts are in play when you take corners on a road course. The faster the car travels, the more it slides out in corners. To stay on the same line, you could apply more steering angle, but if you are already close to the limit of tire grip there is simply no more grip available, and trying to turn more won't achieve anything. The alternative is asking the car to start turning earlier and allowing it to slide laterally more, in the end placing it back on the desired line.
Note that turning in earlier is an advanced driving technique and is roughly opposite of what novice drivers are taught. Apply it with due care.