Tire wear pattern.
Where your car tires wear the most? Inside(towards the center of the car), center or outside(towards the outside of the car)? Do you have to run more camber to balance wear?
Tire wear pattern changes with tire load as you know so when you have a very spread wear pattern starting from the center of the tire you know the suspension is using all the grip the tire has to offer. Again, if you have to run more camber to balance the wear something isn't right, let it roll more.