Exactly. Of course that's assuming perfectly rigid wheels and ground. Tanks have tracks because they often encounter ground that's everything but rigid. Distrib

Exactly. Of course that's assuming perfectly rigid wheels and ground. Tanks have tracks because they often encounter ground that's everything but rigid. Distributing your load over more area reduces the forces experienced by the ground, allowing it to stay put. Same idea with putting more wheels on a truck, or reducing tire pressure when driving in sand. Meanwhile race cars tend to have trouble with the tires not being rigid enough, driving them to bigger tires. But that doesn't allow you to exceed the theoretical max grip, and in that formula surface area cancels out.