How Much Difference Between the Car Speedometer and the Actual Speed?

[McEva]

When the car speedometer shows 110, the actual speed may not have reached 120km/h. However, if you change the tires midway, the car will measure speed based on the rotation speed of the tires. If the tire size increases, the rotation speed at the same actual speed will decrease, causing the speedometer to display an incorrect reading. In this case, the speed shown on the dashboard may be lower than the actual speed. Here are some additional details: Early deceleration: When encountering speed cameras, you should still rely on the speedometer. Therefore, it is essential to decelerate in advance and maintain a speed at least 5km/h below the maximum speed limit to ensure no speeding violation. Speedometer: The car speedometer only provides an approximate speed, so even if you decelerate before a speed camera, the inertia from the car body may prevent the speed from decreasing sufficiently, leading to speeding.