Here is a measurement to start with. A Super Formula Lights 324, braking as hard as it can at Silverstone, slows at 1.10 g when it is traveling below 126 km/h. The same car, on the same lap, with the same brakes and the same four tires, slows at 2.29 g when it is traveling above 180 km/h.

Twice the stopping power, and nothing about the car changed between the slow corner and the fast one. No component was swapped. The brake discs did not grow. The rubber compound did not improve down the straight.

A number like that is a loose thread. Pull on it and the entire subject of tires and grip unravels into the open, because the explanation for that one measurement touches everything: what grip actually is, where it comes from, what strengthens it and weakens it, and why a race car is shaped the way it is. That is what this post is, an introduction to tires and grip from zero, with a running start provided by one strange, verifiable fact.