Q: “I was wondering, as you progress through a race and you lose fuel and your tires get worn out, do you have to change your racing line, braking points, apex, etc.?”
A: Depending on the car, yes, for sure you have to adapt. First, as fuel burns off, the car gets lighter, which means you can brake later, carry more cornering speed, and get back to throttle sooner. Of course, that depends a little on the overall weight of the car and how much fuel the car is carrying as a percentage. Twenty-five gallons in a 2000-pound car will make a much bigger difference than fifteen gallons in a 3500-pound car. Then you factor in tire wear, and that can either balance out the gain in performance from the lighter weight, not be much of a factor, or make a big difference. Again, it depends on how much the tires go “off” over the course of a race.
Brake points are probably the biggest changeable factor, with the line not changing that much. Of course, part of your job as race driver is to search out and use track grip, and that can change depending on the condition your tires are in, as well as your car’s weight.
Something that you may want to change as the car gets lighter is the gear used in corners. For example, if there’s a corner that is right in between 2nd and 3rd gear, you might use 2nd when the car is heavy with fuel, and 3rd when it’s lighter as fuel burns off. But again, reduced tire grip might outweigh the benefits of the lighter weight.
If the car has gotten much lighter as a percentage of overall weight, the car will accelerate faster, too. That means you may be at a higher speed when you get to the end of straightaways, and therefore the advantage in braking is used to compensate for the higher speed. In other words, you’re going faster, you have more braking performance, but you need to brake at the same place as usual because those two factors compensate for each other.
Hey, adapting is one of the things that make our sport so much fun. If it was all the same, it could get boring, right?! 🙂