An off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with deep, open treads, a flexible suspension, or even caterpillar tracks. Other vehicles that do not travel public streets or highways are generally termed off-highway vehicles, including tractors, forklifts, cranes, backhoes, bulldozers, and golf carts.
Off-road vehicles have an enthusiastic following because of their many uses and versatility. Several types of motorsports involve racing off-road vehicles. The three largest "4-wheel vehicle" off-road types of competitions are rally, desert racing, and rockcrawling. The three largest types of all-terrain vehicle (ATV)/motorcycle competitions are Motocross, Enduro, and also desert racing like Dakar Rallye and Baja 1000. The most common use of these vehicles is for sight seeing in areas distant from pavement. The use of higher clearance and higher traction vehicles enables access on trails and forest roads that have rough and low traction surfaces.
To be able to drive off the pavement, off-road vehicles need several characteristics: They need to have a low ground pressure, so as not to sink into soft ground, they need ground clearance to not get hung up on obstacles, and they need to keep their wheels or tracks on the ground so as not to lose traction. Wheeled vehicles accomplish this by having a suitable balance of large or additional tires combined with tall and flexible suspension. Tracked vehicles accomplish this by having wide tracks and a flexible suspension on the road wheels.
The choice of wheels versus tracks is one of cost and suitability. A tracked drivetrain is more expensive to produce and maintain. Wheeled drivetrains are cheaper and give a higher top speed. The tracked drivetrain has greater off-road capability.
Most off-road vehicles are fitted with especially low gearing. This allows the operator to make
the most of the engine's available power while moving slowly through challenging terrain. An internal combustion engine coupled to a normal gearbox often has an output speed too high. The vehicle often has one of two things, either a very low ("granny") first gear (like the all wheel drive Volkswagen Transporter versions) or an additional gearbox in line with the first, called a reduction drive. Some vehicles also have torque converters to further reduce the gearing.
Many wheeled off-road vehicles provide power to all wheels to keep traction on slippery surfaces. For a typical four-wheel vehicle this is known as four-wheel drive. Vehicles designed for use both on and off road may be designed to be switched between two-wheel drive and four-wheel drive so that the vehicle uses fewer driven wheels when driven on the road.