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do you have to recalibrate your speedometer for larger tires
Do you have to recalibrate your speedometer for larger tires?Yes. Changing the tire size will not affect the speedometer reading, but may affect the actual speed. We can analyze this problem from the following three aspects.
1. No matter how the tires are changed, the speedometer display will not change, but the GPS speedometer will have an impact. The speedometer is calculated by wheel speed signal or transmission output shaft speed signal. For example, if the tyre circumference of a vehicle is 1.8 meters, we only need to know the wheel speed to calculate the vehicle speed. For example, the current wheel speed sensor detects that the wheel speed is 200 rpm. Then the current vehicle's driving distance per hour is 200 * 1.8 * 60=21600 meters, and the converted speed is 21.6 km/h. When you change the tire diameter, the distance traveled by the wheel in one revolution will change, but the computer on the dashboard does not know it, and it will still calculate according to the factory set ratio. At this time, the actual speed is inconsistent with the displayed speed. When the tire diameter increases, the actual speed increases, and when the tire diameter decreases, the actual speed decreases. For example, the actual speed of the big guy in the above figure must be lower than the speed shown on the speedometer. The GPS speedometer is calculated based on the actual moving speed of the vehicle, so the speed calculated at any time is the actual speed of the vehicle.
2. The tire diameter remains unchanged, without any influence. It is the tire diameter that determines the vehicle speed, because the wheel is rolling when the vehicle is driving. Every time the wheel rotates, the forward distance is equal to the tire circumference, which is only related to the tire diameter. Therefore, if the diameter does not change after changing the tire size, the vehicle speed will not be affected. Some cars have different sizes of high and low configuration wheels. For example, a low configuration car uses 17 inch wheels and 225/65R17 tires. However, the high configuration model uses 18 inch wheels, so the tires should naturally be replaced with 225/60R18 suitable for 18 inch wheels. It can be seen from the calculation that the diameters of the two tyres are almost the same, so this exchange will not affect the speedometer display nor the actual speed.
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