A wheel arrangement for a four-wheeled vehicle is comprised of a front wheel, two side wheels and a rear wheel, whereas the rear wheel is connected to the frame of the vehicle by a supporting base enabling the same to be steered freely while having a ground-touching point of the same to be biased from the axis of the supporting base by a distance, and the front wheel can be specified as a driving wheel, a free-rolling steering wheel or just a steering wheel with respect to actual requirement, and the two side wheels can be specified as a driving wheels or free-rolling wheels while enabling the axis of the two side wheels to be aligned to a straight line without sharing a same shaft. The wheel arrangement can be a rhombus configuration as the distances between the center of the front wheel and the centers of the two side wheels are the same as that of the center of the rear wheel and the centers of the two side wheels, or can be a diamond configuration as the distances between the center of the front wheel and the centers of the two side wheels are different from that of the center of the rear wheel and the centers of the two side wheels.