Maximum Speed on a Flat Curve

On a flat curve the only thing pointing toward the centre is tyre friction, so μₛmg must cover mv²/r. The mass cancels — a loaded truck and an empty hatchback with the same tyres can theoretically corner at the same speed — leaving v_max = √(μₛgr). Dry asphalt with μₛ ≈ 0.8 on a 50 m radius allows √(0.8 × 9.80665 × 50) ≈ 19.8 m/s, about 71 km/h.

Now halve the grip: wet asphalt at μₛ ≈ 0.4 drops the limit to 14 m/s, and packed snow near 0.15 leaves only 8.6 m/s on that same curve. Because speed enters as a square root, grip losses are less brutal than they feel, but the flip side is that the required friction grows with v² — 20% more speed demands 44% more grip. The formula also assumes friction is doing nothing else, so a driver braking or accelerating mid-corner is spending part of the same friction budget, the "friction circle" that racing drivers train around.