轨道和公路车辆中，轴距是指前后车轮轴心的距离。

汽车的轴距是指前轮轴心和后轮轴心之间的水平距离。车辆在平衡时的净转力矩为零，由此轴距和各个车轮承受重量的关系可以用以下公式来表述：

是前轮所受重量， 是后轮所受重量， 是轴距， 是重心(CG)到后轮的距离， 是重心到前轮的距离， 是车辆的质量， 是重力加速度。

In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels. For road vehicles with more than two axles (e.g. some trucks), the wheelbase is defined as the distance between the steering (front) axle and the centerpoint of the driving axle group. In the case of a tri-axle truck, the wheelbase would be the distance between the steering axle and a point midway between the two rear axles.