The rear axle speed ratio is the gear ratio of the main reducer in the drive axle of an automobile. It is equal to the ratio of the rotational angular velocity of the drive shaft to the rotational angular velocity of the axle half of the axle, and it is also equal to the ratio of their rotational speeds.
Truck speed = engine speed / gear speed ratio / transaxle speed ratio * tire diameter. When the truck enters the highest gear, the rear axle speed ratio determines the maximum speed of the truck. The rear axle speed ratio is smaller but the maximum vehicle speed is larger but The torque is small. Conversely, the vehicle speed is small but the torque output is large.