The front wheel steering system of conventional vehicle fails to keep the vehicle stable at high speeds and prove futile for heavy vehicles like tracks and trailers, especially in tight space. But if the rear wheels too could be steered, manoeuvrability of the vehicle will be enhanced. This results in the evolution Four-wheel steering (4WS). In 4WS, rear wheel are also steered in combination with the front wheels. This system helps in achieving superior cornering stability, improved steering responsiveness and precision, high –speed straight-line stability and a smaller turning radius and tight-space manoeuvrability at low vehicle speed range. Four-wheel steering is of course a beneficial technology. Due to the high cost of manufacturing and complexity in design the 4 WS system is fitted only to certain heavy and special utility vehicles. But the advancing development in electric steering system, the future may see more cars fitted with rear wheel steering..
