Oversteer is when the rear tires reach the limit of their grip before the fronts, so the kart rotates more than the steering input asks for and the back steps out toward the outside of the corner. Taken far enough, the driver has to catch the slide with opposite lock or lift.
What it feels like: the kart turns in eagerly, then the rear starts to come around and you're suddenly correcting rather than driving the line. A little rotation can be quick; too much scrubs speed and risks a spin.
Like understeer, oversteer has two kinds of cause, and the free one is worth checking first:
- Driver-induced. An abrupt lift or brake in the middle of a corner, too much throttle too early, or a snatchy hand on the wheel can all unsettle the rear and provoke a slide the setup isn't to blame for.
- Setup- or kart-induced. Rear grip, weight distribution, tire pressures, and — on a solid-axle kart — how much the chassis unloads the inside rear all shape how willing the rear is to let go. Those belong to the setup side.
Because a kart rotates by unloading its inside rear, a chassis that jacks too much or runs the rear too light can feel loose or start hopping, which reads as oversteer. Sorting a driving cause from a chassis one is what is it the kart or is it you? covers, with the mechanism in diagnosing hopping and binding.
See also: Understeer, Racing line fundamentals. Related terms: apex, turn-in.