All wheel steering
refers to a vehicle that has a steering system attached to each of the four wheels. Most passenger vehicles are front wheel steering
only, i.e. only the front wheels turn to maneuver and the rear wheels are locked in place and only allowed to spin axially. Rear wheel steering is often added to vehicles to improve closed-space turning performance or high speed cornering.
Many industrial vehicles, forklifts, transports, and trucks, are equipped with an all wheel steering system that utilizes opposite phase. When the front wheels turn, the rear wheels turn the opposite direction. This allows for a much tighter turning radius at slower speeds. This type of system is less favorable at higher speeds because of its circular tendency. The 2002 GMC Sierra Denali is a passenger truck recently advertised to have opposite phase all wheel steering.
In phase all wheel steering refers to a system where the rear wheels turn in the same direction as the front wheels. This type of system is more favorable at higher speeds, to improve the cornering ability. Some 1992-1996 Honda Preludes had all wheel steering. All Mitsubishi 3000GT VR-4s and Dodge Stealth R/T Twin Turbos are equipped with an in phase system, where the rear wheels turn up to three degrees at speeds over 30 miles per hour. The twin turbo Nissan 300ZX also has this system.