with numerous pots and bumps at the maximum speed. Drivers mostly use Rear Wheel Drive and 4 Wheel Drive trucks with long-travel suspension, wide stance on the front and large tires which allows maintaining optimal stability at the high speed. This type of trucks are often called Prerunner. These events, depending on the specific event, can last days, even possibly spanning across hundreds of miles. Rock racing Rock Racing is very similar to rock crawling in the fact that the vehicles are driven over rocks, the difference is that there are no penalties for hitting cones, backing up or winching as is done in rock crawling. Rock racing also involves a degree of high-speed racing not seen in typical rock crawling. Rally See article: Rally Mudding and mud plugging Mudding is off-roading through an area of wet mud or clay. The goal is to drive through as far as possible without getting stuck. There are many types of tires that are recommended for this activity. Some tires are balloon tires, mud-terrain tires and paddle tires. This activity is very popular in the United States, although it is illegal on public land due to the environmental impact. Mud plugging, as practiced for instance in the United Kingdom, refers to the old motorsport of classic trials, where again, the main objective is to complete a challenging course of (mostly unpaved) roads and (often muddy, and frequently uphill) off-road terrain. This form of motor sport is one of the earliest to survive to this day, dating back at least to the 1920s. Rock crawling Rock crawling is a category of off-roading. Vehicles used for rock crawling are usually modified with different tires, suspension components that allow greater axle articulation, and changes in the differential gear ratio in order to obtain characteristics suitable for low speed operation for traversing obstacles. It is common for a rock crawler to have a "spotter", who is an assistant on foot by the vehicle to provide information to the driver about the areas out of sight to the driver. Competitive trials All progress is made at low speed and the emphasis is on skill, rather than finishing first although trialing can be highly competitive. There are three traditional forms of off-road trialing. RTV trialing RTV (Road Taxed Vehicle) trialing is the most common form of trialing. As the name suggests, it is for vehicles that are road-legal (and