Camber is the tire's lean from vertical, viewed from the front of the car, measured in degrees. Negative camber leans the top of the tire toward the chassis; positive camber leans it away.
On an oval, the two front corners get opposite signs because they’re on opposite sides of the turn — negative on the right front, positive on the left front, so both tires stand up flat as the car rolls and loads. Get Started Racing describes right-front settings as “huge amounts of negative camber” against a small positive number on the left. Exact degrees are chassis-, track-, and banking-specific, so take them from your builder’s sheet, then confirm with a probe pyrometer: inside edge much hotter than outside means more camber than that corner’s load wants. Measure with a caster/camber gauge on the spindle or hub. RC cars run negative camber at all four corners for the same reason.
Camber decides how much tread is actually on the track when the car is loaded, which is the difference between using a whole tire and half of one.