Calculate speedometer error when changing tire sizes. See actual speed vs displayed speed for 60, 80, 100, 120 km/h.
Enter your original and new tire sizes (width/aspect ratio/rim diameter) to calculate the speedometer error rate. A larger tire diameter means your actual speed is faster than displayed.
An error rate within ±3% is generally acceptable. Larger errors may cause issues with speed limit enforcement and odometer accuracy.
Tire size notation: 205/55R16 → Width 205mm, Aspect Ratio 55%, Rim Diameter 16 inches