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bigger tires speedometer faster or slower
If friction and other factors are not taken into account, the theory that the bigger the tire, the faster the speed is can stand up. Because the diameter of the tire increases, the angular speed does not change, but the linear speed will increase. The vehicle speed can be increased when the vehicle is in the same gear. However, the torque of the engine needs to be improved, and the engine needs to consume more fuel. Although the speed increases, the fuel consumption also increases correspondingly.
No matter how you change the tire, the speedometer display will not change, but the GPS speedometer will have an impact. The speedometer is calculated by the wheel speed signal or the transmission output shaft speed signal. For example, if the tire circumference of a car 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. So the current vehicle's distance per hour is 200 * 1.8 * 60=21600 meters, which is 21.6 kilometers per hour.
When you change the diameter of the tire, the distance that the wheel travels after one revolution changes, but the computer on the instrument panel does not know, it will still be calculated according to the factory-set ratio. At this time, the actual speed and the displayed speed will be inconsistent. 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 above 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 its calculated speed at any time is the actual speed of the vehicle.
The tyre diameter remains unchanged without any influence. The vehicle speed is determined by the tire diameter, because the wheels are rolling when the vehicle is running. The forward distance of each wheel revolution is equal to the tire circumference, and the tire circumference is only related to the tire diameter. So if the diameter does not change after changing the tire size, the vehicle speed will not be affected. Some cars have different hub sizes for high and low configuration. For example, a low configuration car uses a 17-inch hub and a 225/65R17 tire. However, the high configuration model uses 18-inch wheel hub, so the tire should naturally be replaced with 225/60R18 suitable for 18-inch wheel hub. 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 display of the speedometer or the actual speed.
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