Well there is no "perfect" point blank.... on guy may feel great with a very soft set-up, and another can only drive the car super stiff..... it's all a matter of feel, will say this though, if the car works well with a softer set-up your tires will last longer than with a stiffer set-up.... I used to use an almost carpet set-up on my cars and wore out foams left ad right (no chunking)
Now I use a softer set-up on asphalt and my foams last a good bit longer.... It's a matter of where you are building traction, in the suspension or forcing your tires to create the extra grip.......