Some auto racing series do not compete in rain or snow, especially series that race on paved oval tracks. Rain and snow both severely diminish the traction between the slick tires and the surface. Other series, especially those that race on road courses such as Formula One and public roads as in rallying, use special treaded rain tires while the surface is wet but not in excessively heavy rain, snow, standing water, or lightning (which is an automatic cessation of racing because of pit crew, race marshals, and safety). Dirt track racing can be run in a light rain as the vehicles have treaded tires. Rallying can be held in rain or snow.