nurkkiirus

Nurkkiirus, a term meaning cornering speed in Finnish, refers to the maximum safe speed at which a vehicle can navigate a curve or corner under given conditions. It is used in driving education, motorsport analysis, and road-safety discussions to describe how speed interacts with curvature, grip, and vehicle dynamics. While the concept is widely used in Finnish automotive contexts, it is often described in English as cornering speed.

In physics terms, the limiting factor is the lateral (centripetal) acceleration required to follow the curve, a_c = v^2 / r, where v is speed and r is the curve radius. The tire–road interface must supply this force through friction. The maximum available lateral force is F_friction = μ N ≈ μ m g, so a rough upper bound for cornering speed is v ≈ sqrt(μ g r). In practice, μ depends on tire condition, temperature, compound, road surface, weather, and load. Vehicle dynamics such as weight transfer, suspension, steering geometry, and aerodynamic downforce also influence grip and thus nurkkiirus. A driver manages nurkkiirus by choosing a driving line, adjusting entry speed, and modulating braking and throttle through the turn.

Measurement and estimation are done via observation, telemetry, or friction tests (skid pads). In racing, cornering speeds are often specified for particular curves; in everyday driving, nurkkiirus informs safe speeds and cornering technique. The term highlights the interplay of grip, radius, and speed in Finnish automotive contexts.